Displays

The Delta/Sigma method is applied in this study to investigate the seismic sequences following major earthquakes, with the aim to understand whether they fit the classical laws of aftershocks occurrence, such as the classical Omori Law and its recent variants, and to explore whether observed deviations from these laws may provide some statistically significant information about the possible occurrence of further large aftershocks. Specifically, the Delta/Sigma method is based on the observation of possible anomalies in the temporal decay of an aftershock sequence. In fact, given the number of events actually observed within a time window U (e.g. 1 day), its difference (Delta) with respect to theoretical number of events, and its standard deviation (Sigma), it was found that, before the occurrence of large aftershocks, the Delta/Sigma ratio may reach rather high values (e.g. above 2-2.5), which can be possibly followed within few days by some relevant aftershocks. The investigation area (referred as "Box") is defined as a rectangular sector, with dimensions proportional to the magnitude M of the mainshock, and with barycenter computed based on aftershocks occurred during the first Tb days from the mainshock.

To investigate the performances of the Delta/Sigma method various earthquake sequences are selected from different regions worldwide, including those associated with recent destructive earthquakes in Italy and Iran. The input data necessary for this study are extracted from global datasets (ANSS-USGS and ISC catalogs) and regional catalogs (e.g. ISIDE bulletins for the Italian territory). A wide set of parametrics tests is carried out in order to verify if this method could forecast the moderate and large aftershocks, which occurred in the region surrounding the mainshocks epicenter. Different input parameters are considered, in order to check the stability and statistical significance of the obtained results.

The preliminary results suggest that the application of Delta/Sigma method could highlight the possible occurrence of several significant aftershocks. Careful assessment of forecasting capability is essential, in order to provide relevant information for mitigation of risks associated with large aftershocks occurrence.

How to cite: Caccamo, D., Pirrone, V., Peresan, A., and Lotronto, R.: Quantifying evolution of aftershocks sequences by Delta/Sigma method: a parametric analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9938, https://doi.org/10.5194/egusphere-egu2020-9938, 2020.

The radiated energy during earthquakes is one of the important characteristics that have a great impact on human lives. The study of the released energy during earthquakes and their distribution may provide a detailed knowledge about the driving forces. The earthquakes occurring between 1994 and 2018 are used to study the spatial distribution of energy in and around Taiwan. The maximum depth of earthquakes used in the present work is 320 km. Hwang's (2012) approach based on local records from Taiwan is used to estimate energy for all earthquakes having  M_L ≤ 6.4. As  M_L saturates for higher magnitude earthquakes, a correction factor is applied to all earthquakes above 6.4 based on energy calculation for Chi-Chi and JiaSian earthquake. It is found that the distribution of earthquake numbers and energy is not uniform. In particular, 99% of the events occurred within 100 km while the remaining 1% occurred from 100 to 320 km. Most of the events, about 78% of the total earthquakes are confined to the upper 20 km depth. Around 90% of energy release in and around Taiwan is contributed by the earthquakes occurring to a depth of 100 km. Only a few earthquakes occur beyond 100 km depth; contributing around 10% of total released energy. The highest energy release is attributed to the eastern subduction along the Ryukyu trench. Our results show that the lower crust may play an important role in energy distribution, though most of the earthquakes have occurred in the upper crust.  So, in addition to upper crust controlling plate-driving forces, the lower crust may also control these forces causing deformation. Therefore, the temporal and spatial distributions of seismic energy release can be further studied to reveal the characteristics of the seismogenic zone in the future.

Keywords: Energy, Magnitude, Subduction, Ryukyu trench, Subduction

How to cite: Mittal, H., Lin, T.-L., and Huang, Y.-H.: Spatial Distribution of Radiated Seismic Energy from Local and Regional Earthquakes in Taiwan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12402, https://doi.org/10.5194/egusphere-egu2020-12402, 2020.

We have used a stochastic approach to simulate a large number of scenarios for in-slab intermediate-depth earthquakes in the southern Aegean Sea Hellenic subduction region, by applying an extended-source model using the EXSIM code. A large database of synthetic ground motion recordings for events with magnitudes in the range M6.0-8.5 has been compiled, covering the whole southern Aegean Benioff zone. For the stochastic simulations, we followed the approach developed in our previous works (Kkallas et al., 2018a,b), where we used the anelastic attenuation from the GMPEs modeling developed by Skarlatoudis et al. (2013) to constrain the different attenuation patterns and properties for the back-arc and fore-arc area. Simulation model parameters, such as stress parameters and attenuation parameters were also adopted from previous works, while for fault parameters we adopted the typical average focal mechanisms proposed by Papazachos et al. (2000), in agreement with the regional subduction tectonics. Estimates of expected ground motion measurements (PGA and PGV values) at different distances from different earthquakes have been employed to generate hybrid Ground-Motion Prediction Equations (GMPE). More specifically, we attempt to modify the existing Ground-Motion Prediction Equations (GMPE) from Skarlatoudis et al. (2013) for intermediate-depth earthquakes along the Hellenic Arc for large magnitude events (M>6.5), so that they can be efficiently used for Seismic Hazard assessment, as the original strong-motion dataset used for their development was lacking data in this magnitude range. Peak ground accelerations and velocities predicted by the EXSIM code are generally in very good agreement with the available GMPE results for magnitudes less than M7. However, significantly lower ground motions than those predicted by the GMPEs are predicted for large-magnitude events (M>7). Using the previous results, we propose a magnitude-dependent correction for the GMPE results both back-arc and along-arc ground motions. Moreover, we demonstrate how the final earthquake ground motion scenarios, as well as the modified GMPEs affect both deterministic and probabilistic seismic hazard analysis. This work has been partly supported by the HELPOS (MIS 5002697) project.

How to cite: Kkallas, H., Papazachos, C., and Vamvakaris, D.: Ground Motions prediction Equations from a stochastic simulation approach for in-slab intermediate-depth earthquakes along the Hellenic subduction zone, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-652, https://doi.org/10.5194/egusphere-egu2020-652, 2020.

We present the results of the intensity prediction equation for Austria as a function of moment magnitude, focal depth and hypocentral distance from the source. This equation aims to be simple and correct to generate shakemaps in near-real-time for crisis management and risk assessment in terms of the impact of an earthquake. Before the model computation, the dataset was carefully selected from the Austrian Earthquake Catalogue (AEC). Then, the model was derived through two Ordinary Least Square Adjustments; the first one was used to calibrate the epicentral intensity, whereas the second one aimed to derive an intensity attenuation law. Additionally, first own-approach to remove local site effects was used to refine the model. In total, the used dataset includes 42 earthquakes befalling in Austria and border regions between 2004 and 2018. Their local magnitude varies between 3.0 and 5.4. In total, 3,214 IDPs with intensity values between III and VII-VIII (EMS-98) were used.

Applications and analysis of the model will be presented. Furthermore, first results to an Austrian hazard map based on intensities will be introduced.

How to cite: Papí Isaba, M. P., Weginger, S., Apoloner, M.-T., Jia, Y., Hausmann, H., Meurers, R., and Lenhardt, W.: Intensity Prediction Equation for Austria: Applications and analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7683, https://doi.org/10.5194/egusphere-egu2020-7683, 2020.

After 25 years, a new seismic hazard map for Austria was created. The improvements in the Probabilistic Seismic Hazard Assessment (PSHA) are based on expanded and updated catalog data with improved depth, source-mechanism and moment magnitudes. Locally adapted ground motion prediction equations (GMPE) were calculated by applying a least square adjustment to the local measurements. A neuronal networks approach was successfully tested. The final selection is carried out by using statistical parameters, like Log-Likelihood and Euclidean Distance Range. Verified calculation methods, like Bayesian Penalized Maximum Likelihood and modified Gutenberg Richter, were used. The uncertainties have been considered by using the covariance matrix according to Stromeyer (2015). The PSHA approach combines a model of seismic zones (area sources), which is composed of zones and superzones, a zone-free model (smoothed seismicity) and a model with geological fault zones. A logic tree function was used to merge the models, the maximum magnitudes (by EPRI-Approach) and the GMPE. The calculations were carried out with the Openquake software framework. The results were compared with the current norm and the results of neighboring countries. Furthermore, the uniform hazard spectra were compared with the new Eurocode draft.

How to cite: Weginger, S., María del Puy, P. I., Jia, Y., and Lenhardt, W.: Seismic hazard map of Austria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4820, https://doi.org/10.5194/egusphere-egu2020-4820, 2020.

Devasting ― and, in some sense, unforeseen  ―  earthquakes in Nepal, Sumatra, Haiti, Japan  and elsewhere have triggered a heated debate about the legitimity and limitations of probabilistic seismic hazard  assessment(PSHA). The authors are coming with many recorded data which will open up a new challenge to seismologists studiing nonlinear site effects in 2-D and 3-D irregular geological structures, leading them to a realistic research subject in earth physics, in nonlinear seismology. Shortly, why are we recording PGA values much higher than epicenter value? There was a need to create, for Europe, a unified framework for seismic hazard assessment and to produce a common integrated European probabilistic seismic hazard assessment (PSHA) model and specific scenario based on modeling tools. The leading question is, if this is happening only in this area of Europe. Vrancea is the site of strong intermediate-depth seismicity, down to 160 – 200 km depth and large magnitudes (M_W ≤ 7.9 - 8.0) and is one of the most active seismic zones in Europe. The latest strong and deep Vrancea earthquakes occurred on August 30, 1986 (Mw = 7.1; h = 131.4 km, in epicenter a=162.60 cm.s² and at Chisinău:212 cm/s²;Focsani:310 cm/s²;Iaşi:181 cm/s²; Otopeni: 220cm/s² etc.); May 30, 1990 (Mw = 6.9; h = 90.9 km; in epicenter: 157 cm/s²; Chişinau:189 cm/s²; Oneşti:242 cm/s²;Periş:242 cm/s²; Bolintin din Vale:219 cm/s²; Campina;271 cm/s² etc. & May 31, 1990 (M_W = 6.4; h = 86.9 km, in epicenter: a=102 cm/s²;Focşani:162 cm/s².There are more than 200 values larger than epicenter ones. More, on October 28,2018 an earthquake (Mw=5.89 and h= 147.8 km ) generate  acceleration of 8.65 cm/s² in epicenter Vrâncioaia and accelerations of   69 cm/s² in Ploieşti; 65  cm/s² in Leova - Republic of Moldova etc. Why in this part of Europe/World there are many peak ground accelerations recorded and are larger than epicenter values ?. Surface waves Rayleigh and Love waves ( A third type of surface wave, the Stonely wave propagates along an interface between two media and is more correctly an interface wave and are not dispersive, thus they decrease in amplitude with distance from the interface) are seismic waves which are guided along the surface of the earth and the layer near the surface and they do not penetrate into the deep interior.

On the other time, the Alpine Tethys was linked to the Euro-Asian back-arc basins located further east through the Moesia - Dobrogea Transform [G. G. Stampfli; http://sp.Lyellcollection.org/by guest on November 14, 2019]. It is observed along new times that in Dobrogea area the peak ground accelerations recorded in last time are smaller than epicenter ones and our Nuclear Power Plant is  safe  to strong Vrancea earthquakes. Peak ground accelerations recorded   in Muntenia, Moldova   and   Republic of   Moldova are maily larger than   Vrancioaia epicenter values (Gh.Mărmureanu, Certainties/uncertainties in hazard and seismic risk assessment of strong Vrancea earthquake. Romanian  Academy Press,2016,330 page,ISBN 978-973-27-2629-7).

How to cite: Marmureanu, G., Balan, F. S., and Marmureanu, A.: Larger peak ground accelerations in extra-Carpathian area than in epicenter, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7215, https://doi.org/10.5194/egusphere-egu2020-7215, 2020.

Near-realtime seismic monitoring of fluid injection allowed control of induced earthquakes during the stimulation of a 6.1 km deep geothermal well near Helsinki, Finland. The stimulation was monitored in near-real time using a deep seismic borehole array and series of borehole stations. Earthquakes were processed within a few minutes and results informed a Traffic Light System (TLS). Using near-realtime information on induced-earthquake rates, locations, magnitudes, and evolution of seismic and hydraulic energy, pumping was either stopped or varied. This procedure avoided the nucleation of a project-stopping red alert at magnitude M2.1 induced earthquake, a limit set by the TLS and local authorities. Our recent studies show that the majority of EGS stimulation campaigns investigated reveal a clear linear relation between injected fluid volume, hydraulic energy and cumulative seismic moments suggesting extended time-spans during which induced seismicity evolution is pressure-controlled. For most projects studied, the observations are in good agreement with existing physical models that predict a relation between injected fluid volume and maximum seismic moment of induced events. Some EGS stimulations however reveal unbound increase in seismic moment suggesting that for these cases evolution of seismicity is mainly controlled by stress field, the size of tectonic faults and fault connectivity. Transition between the two states may occur at any time during injection, or not at all. Monitoring and traffic-light systems used during stimulations need to account for the possibility of unstable rupture propagation from the very beginning of injection by observing the entire seismicity evolution in near-real-time and at high resolution could possibly provide a successful physics-based approach in reducing seismic hazard from stimulation-induced seismicity in geothermal projects.

How to cite: Dresen, G., Bentz, S., Kwiatek, G., Martínez-Garzón, P., and Bohnhoff, M.: Characteristics of induced seismicity during hydraulic stimulations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22444, https://doi.org/10.5194/egusphere-egu2020-22444, 2020.

Probabilistic seismic hazard analysis (PSHA) models typically provide estimates of ground motions for return periods that exceed historical observations. It is therefore important to develop quantitative methods to evaluate and refine ground motion estimates for long return periods, especially in proximity to major earthquake sources where estimates can be very high. Here we provide empirical constraints over 10,000s years on ground motions from onshore and offshore seismic sources in central California using the distribution, age and fragility (probability of toppling given an intensity of ground shaking) of fragile geologic features.

The fragility is estimated for seven precariously balanced rocks (PBRs) formed on uplifted marine terrace palaeo-sea stacks. The site is <10 km from the Hosgri fault, a major offshore fault considered part of the San Andreas fault system. PBR 3D models were constructed using photogrammetry and used to define normalized geometric measures that could be combined with empirical models to estimate the probability of toppling (i.e., fragility), over a range of vector ground motions (PGA and PGV/PGA). Using vector hazard and the fragility, the likelihood of survival was then computed. The PGA associated with a 50 percent chance of survival varies from ~0.4-1.3 g for the selected PBRs.

We obtain fragility ages (time that each PBR achieved its current geometry) using Be-10 cosmogenic surface exposure dating. Extremely low Be-10 concentrations (~5000 at/g) in modern high-stand samples demonstrates minimal inheritance and reliability of chert age estimates. Additionally, the volume of colluvium surrounding the palaeo-sea stack outcrops, determined from LiDAR, combined with alluvial fan surface dating (using Be-10 and soil profile development indices) indicates low erosion rates (~2.5 mm/ky) and long-term stability. Exposure ages that bound the fragility age by approximating the removal of surrounding blocks range ~17-95 ky. The similar age distributions of block removal events around all of features suggests that all PBRs share a common evolution, and we interpret ~21 ka as the most defensible fragility age estimate of all seven PBRs, with negligible change to their fragility between that time and now. Despite the lack of constraints on the recurrence behaviour of the Hosgri Fault, the slip rate is such that the PBRs have almost certainly experienced multiple large-magnitude, near-field earthquakes, and therefore provide rare constraints on low frequency ground motions.

Each estimate output from the PSHA model is evaluated against the ground-motion corresponding to the 95% probability of survival of the most fragile PBR over the 21 ka fragility age. The logic tree branches that produce estimates inconsistent with the survival of the PBR are removed from the PSHA model. From the consistent logic tree branches a new PSHA model is produced that has reduced mean ground-motion levels and reduced uncertainty between the estimates. At the 10^-4 hazard level, the mean ground motion estimate is reduced by ~30% and the range of estimated 5^th-95^th percentile ground motions is reduced by ~50%.

How to cite: Caklais, A., Rood, D., Stirling, M., Madugo, C., Abrahamson, N., Wilcken, K., Gonzalez, T., Kottke, A., Whittaker, A., Page, W., and Stafford, P.: Earthquake hazard assessment uncertainty reduced by fragile geologic features in coastal Central California, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14971, https://doi.org/10.5194/egusphere-egu2020-14971, 2020.

The need to model seismic capacity of stalagmites derives from the objective of speleoseismology to study long term seismic hazard [1], [2], [3]. Assessment of the seismic capacity of stalagmites is done in terms of peak ground acceleration, which would break the stalagmite. The problem is not easy for many reasons: (1) the shape and internal structure is neither uniform nor isotropic, (2) it is well known from seismic engineering that to model breaking of a vertical cantilever may require knowledge of a full time history of accelerations (PGA, duration, spectral content) and (3) that one may also need to consider multicomponent seismic effects (e.g. including rocking component [4], [5]).

So far the seismic models of stalagmites are modeled as beams with intervals of constant cross-sections (e.g. [2]). In order to develop more sophisticated Finite Element Models (FEM), including also their random properties, one may require to calibrate the models by breaking some real stalagmites which, for obvious reasons is not possible. However, some short pieces of broken stalagmites can be found in the caves and used in the breaking experiments. The real stalagmites often represent the slenderness ratio (λ = height/width) of the order of 40 or more. It is well known that modes of failure of such slender objects are different than the failure modes of short, stocky beam.

Thus, before any experimental validations of the FEM models of the stalagmites are undertaken, numerical modeling of bending and shear seismic capacities of short and slender beams must be compared and respective breaking parameters should be determined.

The purpose of the lecture proposed for session NH4.2/SM3 is to present results of numerical analyses of 3D FEM models of short (λ = about 10) and long beams (λ = about 40). Results of such numerical simulations will help to design proper breaking experiment on the pieces of stalagmites and help calibrate future FEM models consisting of many thousands of finite elements including random, nonuniform structure of tested stalagmites.

References

[1] Becker A., Davenport C. A., Eichenberger U., Gilli E., Jeannin P.-Y., Lacave C., (2006), Speleoseismology: A critical perspective, Journal of Seismology, 10, pp. 371–388, DOI 10.1007/s10950-006-9017-z

[2] Gribovszki K., Kovács K., Mónus P., Bokelmann G., Konecny P., Lednická M., Moseley G., Spötl C., Edwards RL., Bednárik M., Brimich L., Tóth L., (2017), Estimating the upper limit of prehistoric peak ground acceleration using an in-situ, intact and vulnerable stalagmite from Plavecká priepast cave (Detrekői-zsomboly), Little Carpathians, Slovakia - first results, J. Seismol., 21(5), pp. 1111-1130, DOI 10.1007/s10950-017-9655-3

[3] Gribovszki K., Esterhazy S., Bokelmann G., (2018), Numerical modeling of stalagmite vibration, Pure and Applied Geophysics, 175, pp. 4501-4514, DOI: 10.1007/s00024-018-1952-4, https://doi.org/10.1007/s00024-018-1952-4

[4] Zembaty Z., Tutorial on Surface Rotations from the Wave Passage Effects — Stochastic Approach, Bulletin of the Seismological Society of America, 99, No. 2B, pp. 1040–1049, May 2009, doi: 10.1785/0120080102

[5] Bonkowski P.A., Zembaty Z., Minch Y.M., Engineering analysis of strong ground rocking and its effect on tall structures, Soil Dynamics and Earthquake Engineering, 2019, 116, pp. 358-370, https://doi.org/10.1016/j.soildyn.2018.10.026

How to cite: Bońkowski, P., Zembaty, Z., Bobra, P., and Gribovszki, K.: Modeling seismic capacity of stalagmites, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20575, https://doi.org/10.5194/egusphere-egu2020-20575, 2020.

The Shillong Plateau is an earthquake-prone region in the northeastern India. Based on regional seismotectonic studies, we present the results of seismic hazard assessment, both deterministic (DSHA) and probabilistic (PSHA), and map peak horizontal accelerations (PHA) for three largely populated districts within the Shillong Plateau - the East Khasi hills, the Ri-Bhoi, and the West Garo hills. The hazard analysis methodology is based on the analysis of 72 earthquake sources (active faults) located within 500 km seismotectonic region around the plateau. Using an average sample log-likelihood approach, suitable ground motion prediction equations (GMPEs) are identified. As a variation in hypocentral distances can affect the ranks (or weights) of selected GMPEs, DSHA is performed separately for the three selected districts. DSHA shows that the northern part of the East Khasi hills, eastern part of Ri-Bhoi district and the West Garo hills districts exhibit the highest PHA value. DSHA indicates that the Barapani, Oldham, and Dauki faults influence significantly the seismic hazard of the studied region. In the case of PSHA, the annual frequency of exceedance of ground motions for three populated cities (Shillong city, Nongpoh, and Tura), located within above three districts respectively, are determined. Individual hazard curves indicate that the Barapani fault possesses the highest frequency of seismic hazard for Shillong city and Nongpoh. At Tura, both Eocene hinge zone and Dauki faults are responsible for the highest frequency of seismic hazard. The results of the PSHA are compared with those obtained using the DSHA approach indicating a difference between the two approaches for the West Garo hills district. It is shown that this difference is associated with the Oldham fault located near the district. The fault can produce a great earthquake, although with a lower probability of occurrence compared to a few other faults capable of producing smaller events with higher probability of occurrence. Hence, in the PSHA, the effect of the Oldham fault is less pronounced in terms of the design life of a structure, than in the case of the DSHA.

How to cite: Ismail-Zadeh, A., Baro, O., and Kumar, A.: Deterministic versus probabilistic seismic hazard assessment for the Shillong Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3834, https://doi.org/10.5194/egusphere-egu2020-3834, 2020.

The 26 December 2004 Sumatra earthquake of Mw 9.2 and the resultant tsunami that claimed over 2,50,000 human lives is probably the most destructive natural disaster of the 21^st Century so far. Although the science of tsunami warning had advanced sufficiently by that time, with several tsunami warning centers operating in various oceans, no such system existed for the Indian Ocean. Here we present the discussions and interactions held in India and globally to convince setting up of ITEWS. False tsunami alarms subsequent to 26 December 2004 earthquake had developed a sense of scientific disbelief in the public and to a certain extent in Government of India. We demonstrated to the national and international community that there are only two stretches of faults that could host tsunamigenic earthquakes as far as the India Ocean is concerned. These are: 1) a stretch of some 4000 km of a fault segment extending from Sumatra to Andaman Islands and 2) an area of about 500 km radius off the Makaran Coast in the Arabian Sea. And if we cover these two areas with ocean bottom pressure recorders, the problem of false alarms would be reduced to a large- extant. This plan was finally agreed to and necessary financial, logistic and technical support was made available. The setting up of the ITEWS started in middle 2005 and was completed in August 2007. It has performed very efficiently since then. Over the past ~ 8 years, it monitored ~ 500 M ≥ 6.5 and provided advisories. As against the requirement placed by IOC of issuing an advisory in 10 to 15 minutes time, ITEWS has been doing it in ~ 8 minutes. Since its inception in 2007, no false alarm has been issued and it is rated among the best in the world.

IOC has designated ITEWS as the Regional Tsunami advisory Provider (TSP) Indian Ocean Regional Tsunami Center.

How to cite: Gupta, H.: Setting up of the Indian Tsunami Early Warning System (ITEWS): National and International Interactions for the Success of ITEWS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4479, https://doi.org/10.5194/egusphere-egu2020-4479, 2020.

The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty is one of the most ambitious global projects ever undertaken by more than 183 states. It’s establishment exemplifies international cooperation through the huge undertaking, coordination and massive investment by all Member States. The IMS monitors the whole earth, atmosphere and undersea for any potential nuclear test but this extraordinary network can also detect and record traces of natural and anthrogenic disasters that are ever present.

The IMS network sets a precedent for reliability, quality and requirements on a global scale. The network is comprised of 4 technologies (seismic, infrasound, hydroacoustic and radionuclide) that monitor the earth’s environments to an incredibly low level and hence is an invaluable resource for monitoring and understanding natural hazards.To date, for example, the CTBTO has signed 14 agreements with tsunami warning organizations for the usage of CTBT data to assist with the timeliness and accuracy of tsunami warnings.

The effectiveness of plans to deal with natural disasters depends on a country’s level of resources and readiness. Member States can rely and call upon the CTBTO and the IMS network to assist them at a time of crisis. The IMS is truly a global network that has no borders.

How to cite: Meral OZel, N. and Jepsen, D.: CTBT IMS - International Cooperation at its finest, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19660, https://doi.org/10.5194/egusphere-egu2020-19660, 2020.

On behalf of the UNDRR/ISC Technical Working Group Task Team

Background - A disaster is a catastrophic event that seriously disrupts a community, with long-term public health, economic and environmental impacts.  The Sendai Framework aims for ‘the substantial reduction of disaster risk and losses in lives, livelihoods and health’.   It advocates an all-hazards approach, to which an understanding of the full scope of hazards faced by communities is essential.  To date there is no scientific list of hazards and definitions encompassing the hazards covered under the Sendai Framework.  This project aims to provide such an overview, which will serve the implementation of the Sendai Framework, and contribute towards the Paris Climate Change Agreement and Sustainable Development Goals.

Methods - A global task team was established by the UN Office for Disaster Risk Reduction and International Science Council, chaired by Public Health England, comprising science and technical experts from UN agencies and the wider scientific community.  Methods included the operationalisation of the UN General Assembly definition of hazard, the development of a hazard taxonomy through consultation with over 500 scientific experts and developing a ‘hazard information profile’ for each hazard describing globally agreed scientific and statistical definitions.

Results - The definition of hazard was operationalised by applying three inclusion criteria:  the potential to affect the functioning of a community, available (proactive and) reactive measures, and measurable spatial and temporal components.  Hazards could be excluded based on complexity.  Overall, 300 hazards were included and described.

Discussion - This novel, scientific endeavour, working at a global scale, marks an important step in the implementation of the Sendai Framework.  The all-hazards taxonomy will provide nation states with a scientific tool to enhance their disaster risk management systems, improving the resilience of some of the world’s most vulnerable communities to disasters.

How to cite: Norris, J., Wright, N., Fagan, L., Mayner, L., and Murray, V.: Taking an all-hazards approach to tackling global disaster risk – an important step towards implementing the UN Sendai Framework for Disaster Risk Reduction, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22175, https://doi.org/10.5194/egusphere-egu2020-22175, 2020.

The characterization of near-Earth-objects (NEOs) with regard to physical attributes and potential risk presents a complex scientific challenge. The societal and policy risks and impacts are no less complex. If, in fact, humankind is finally at the stage where it can technically prevent or mitigate a catastrophic asteroid impact, through deflection or other physical means, the question remains as to whether or not humankind has the political will, and appropriate institutions, to do so. As such, planetary defense represents a unique opportunity to link public policy theory and disaster diplomacy with regard to a low probability/high risk problem. What challenges does this opportunity raise, and how should we look into this situation? The problems of NEOs, asteroids and planetary defense and the solutions prescribed to address them presents an interesting and unique challenge for public policy theory. David Morrison’s definition of the problem (2010) sets the diplomatic and policy stage…  “the potential exists for an impact catastrophe at any time, in any country, with little or no warning.” Current planetary defense policy approaches can be characterized into three areas:

1) Identification, characterization, and monitoring of objects and their potential threat. Creation of the concept of “planetary defense” which is a policy statement in itself, and the institutionalization of PD (NASA, ESA, UN, interagency working groups, universities).

2) Response (solution) type 1, or the determination and implementation of effective deflection or mitigation responses. The solution is more science and technology.

3) Response (solution) type 2, the traditional civil defense and natural hazard response, preparation and response activities.

Are NEOs scientific and technological problems to be “solved” through more research funding, decrease the uncertainty, or are they more of a traditional civil defense problem, global security problem, or even an opportunity for larger issues of the peaceful and legal use of space and the economic exploitation of space resources? Each of these definitions of the “problem” is connected to potential “solutions,” which compete for attention and resources with significant implications for disaster diplomacy and governance. This contribution will connect current disaster diplomacy thinking with our understanding of the policy challenges from low probability/high consequence disaster events.

How to cite: Lindquist, E.: Disaster diplomacy and planetary defense: a policy perspective on low probability events, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9958, https://doi.org/10.5194/egusphere-egu2020-9958, 2020.

Long-term information can be gained from intact and vulnerable stalagmites in natural caves. These formations survived all earthquakes that have occurred, over thousands of years - depending on the age of the stalagmite. Their “survival” requires that the horizontal ground acceleration has never exceeded a certain critical value within that time period.

Here we present such a stalagmite-based case study from the Gömör-Torna karst region, Slovakia. A candlestick shaped, intact and vulnerable 4.51 m tall stalagmite in Domica cave, Ördöglik Hall has been examined in situ many times since 2012. The examination of candlestick shaped, intact and vulnerable (IVSTM) in Domica cave, Ördöglik Hall (southeastern Slovakia) is the continuation of our previous examination of intact, vulnerable stalagmites in other caves in Hungary, Bulgaria, Slovakia and Austria. The aim of our investigation is to estimate the upper limit for horizontal peak ground acceleration generated by paleoearthquakes.

The method of our investigation is the same as before: the density, the Young’s modulus and the tensile failure stress of broken stalagmite samples have been measured in mechanical laboratory, whereas the dimensions and the natural frequency of IVSTM were determined by in situ observations. The value of horizontal ground acceleration resulting in failure and the theoretical natural frequency of IVSTM were assessed by theoretical calculations.

New results of age determination of drilled core samples from Ördöglik Hall, Domica cave are available. The age has been determined by Multi Collector – Inductively Coupled Plasma Mass Spectrometry analysis (MC-ICPMS). Our measurements show, that the base part of the IVSTM is not older than 10 kyears.

The critical horizontal ground acceleration values as a function of time going back into the past determined from stalagmite, that we investigated (IVSTM), are presented. This result have to be taken into account when calculating the seismic potential of faults near to Domica cave (e.g. Darnó and Rozsnyó lines).

How to cite: Gribovszki, K., Pinti, D., Shen, C.-C., Mónus, P., Prácser, E., Novák, A., Kiszely, M., Esterhazy, S., Czirok, L., and Lednicka, M.: Long term seismic hazard information from intact, vulnerable stalagmites in Domica cave, O:rdo:glik Hall, Slovakia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5491, https://doi.org/10.5194/egusphere-egu2020-5491, 2020.

In Japan, seismic observation using modern instruments was started at the end of the 19th century, and the nationwide seismic observation network was developed in the early 20th century. Therefore, to study earthquakes that occurred before the start of modern seismic observation, it is necessary to conduct research and analysis based on historical documents.
Since the end of the 6th century, there have been various types of historical documents describing earthquakes and their damage in Japan. Especially since the 10th century, historical source journals have described not only large earthquakes that caused great damage, but also small earthquake quakes. In Japanese history, pre-modern diaries were considered as semi-official archives intended for future reference and are used in various studies as reliable primary archives.
The history diaries have the following features: (1) their descriptions are highly reliable because they were written immediately after the event or on the same day. (2) You can specify exactly where the history diaries were recorded. (3) The same author kept a diary for ten to several decades, providing continuous and stable information. (4) In some areas in Japan, historical diaries have existed almost continuously since the 10th century.
In this study, many such history diaries are accumulated over a wide area in Japan, and the descriptions of felt earthquakes are extracted and digitized, and a database has been constructed so that the digitized information can be easily used for seismology research. In the prototype of the "Historical Diary-based Sensible Earthquake Database" introduced at the previous meeting, the diary historical data at 28 locations and 2,767 felt earthquakes were registered for four years from 1853 to 1856 (Nishiyama et. al., 2019).
Since then, the database was released in a website, and the data has been expanded to 47 locations and 3,376 felt earthquake data for the same period. The database includes the date and possible occurrence time of the earthquake, the recording location, and the magnitude of shaking. In order to efficiently utilize this database for seismology research, we also have developed a graphic user interface (GUI) with the following functions.
(a) A function to display the locations where shaking was recorded during the same time period on the same map, and plays the specified period as a moving image.
(b) A function to examine whether a felt earthquake recorded at different locations on the same day is caused by the same earthquake. The possible time periods of each shaking are displayed side by side.
This database and the newly developed GUI eliminate the need to read historical diaries, which requires the specialty of history. Utilizing digitized data, it is expected to promote seismology research, such as elucidation of long-term seismic activity including not only large-scale but also small- and medium-scale earthquakes.

How to cite: Nishiyama, A., Ebara, M., Mizuno, R., Yoshioka, S., Katagiri, A., and Oishi, Y.: Daily felt earthquake database based on historical diaries of pre-modern Japan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3721, https://doi.org/10.5194/egusphere-egu2020-3721, 2020.

Nowaday, macroseismic data are still essential for the seismic hazard assessment in several regions because they provide important knowledge on preinstrumental earthquakes, nedeed to compile historical earthquake catalogs. This is especially true for Italy, which boasts a large and accurate macroseismic database, DBMI15, composed by 122701 macroseismic records related to 3212 earthquakes occurred from 1000 up to 2014. It should be noted that some records are incomplete or the available information is insufficient for the assignment of the intensity at a given site (e.g. intensity IX-X denotes that the level of damage at that site is uncertain and evaluated IX or X with a probability of 50% each). In order to respect both the ordinal nature of macroseismic intensity and its tendency to decrease with distance from the epicentre, we consider the beta-binomial model by Rotondi and Zonno (Ann. Geophys., 2004; Rotondi et al., Bull. Earthq. Eng., 2016) which describes the probability distribution of the intensity at a site, conditioned on the epicentral intensity and on the epicentre-to-site distance. The application of the beta-binomial model typically requires rounding-up or -down the observed intensities to the nearest integer values. We propose an extension of the beta-binomial model in order to include in the stochastic modelling the uncertainty in the assignment of the intensities. Then we exploit the advantages of the Bayesian approach for uncertainty quantification both in the estimation procedure and in the forecast of damage scenarios.

How to cite: Varini, E. and Rotondi, R.: Probabilistic damage scenarios from uncertain macroseismic data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6152, https://doi.org/10.5194/egusphere-egu2020-6152, 2020.

Near fault ground motions may contain impulse behavior on velocity records. Such signals have a particular indicator which makes it possible to distinguish them from non-impulsive signals. Impulsive signals have significant effects on structures; therefore, they have been investigated for more than 20 years. Due to its severe effect on structures, it is vital to predict its occurrence during an earthquake. To calculate the probability of occurrence, a large dataset is collected from various national data providers and NGA-West 2 database. The dataset only contains crustal earthquakes. Created dataset has a large number of parameters which carry information on the earthquake physics, ruptured faults, ground motion parameters, distance between the station and several parts of the ruptured fault. Relation between the parameters and impulsive signals are calculated. It is found that fault type, moment magnitude, distance and azimuth between a site of interest and the surface projection of the ruptured fault are correlated with the impulsiveness of the signals. These parameters are given as inputs to multivariate naïve Bayes classifier. Naïve Bayes classifier allowed us to have the probability of observing impulsive signals. Two separate models are created for strike slip and non-strike slip fault types. It is found that strike slip and non-strike slip models have an accuracy rate of 98%. These models are able to predict the probability of observing an impulsive signal for a site of interest with high accuracy rates.

How to cite: Ertuncay, D. and Costa, G.: Determination of Near Fault Velocity Pulses with Multivariate Naïve Bayes Method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4810, https://doi.org/10.5194/egusphere-egu2020-4810, 2020.

A seismic hazard analysis was conducted for a site in Papua New Guinea which is located in a seismically-active region that experiences frequent large earthquakes generated by crustal and subduction sources.  A suite of ground motion prediction equations (GMPEs) was developed for each source type (crustal, interface and in-slab) using the scaled-backbone approach.  To this end, a ground-motion database consisting of events of 4.0<Mw<8.0 was compiled from available local and regional monitoring stations.  Ground motions were classified based on the source type and converted to a common reference site condition.  The site-corrected motions were compared against alternative GMPEs to examine residual trends between observed and predicted amplitudes.  A backbone model that represents the best estimate of the median ground motions for each source type was selected.  The backbone models were then adjusted to the median of the ground motions observed at the study site.

The epistemic uncertainty in median predictions was modeled using a logic-tree approach, where the distribution of potential median predictions is approximated by a lower, central and upper model.  The central model is represented by the site-adjusted backbone model; it was scaled to define the lower and upper branches.  The scaling factor was determined considering: (i) the standard deviation in median prediction of alternative GMPEs; and (ii) epistemic uncertainties recommended in other studies.  The available data were insufficient to model aleatory variability with confidence; therefore, the standard deviation of observed motions in data-rich regions is used for guidance.  Two alternative aleatory variability models (ergodic and single-station sigma) adopted from other studies are recommended.

How to cite: Novakovic, M., Yenier, E., Hovey, A., Quinn, J., and Witten, B.: Site-Specific Characterization of Earthquake Ground Motions: Papua New Guinea Case Study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12388, https://doi.org/10.5194/egusphere-egu2020-12388, 2020.

Two earthquakes having almost the same magnitude and focal mechanism occurred in Hualien County, Taiwan, in 2018 and 2019. The 2018 earthquake had a magnitude  M_L6.2 produced severe destruction; however, the 2019 earthquake ( M_L=6.3) did not cause any significant damage. The P-Alert instrumentation network consisting of 711 instruments provided high-quality real-time peak ground acceleration (PGA) and peak ground velocity (PGV) shakemaps during both events. Considering recorded PGA, both events should cause substantial destruction. On the contrary, PGV shakemaps display a different pattern. The higher PGV values (more than 17 cm/s) are observed in the rupture zone during the 2018 earthquake (locations suffering building collapse) as compared to the 2019 earthquake, proving the fact that PGV is a better indicator of damage distribution. The PGV shakemap, currently only available for P-Alert network, provides crucial information that complements the PGA issued by the official agency in Taiwan

How to cite: Wu, Y.-M.: Importance of Real-time PGV Shakemaps: Experience from 2018 ML 6.2 & 2019 ML 6.3 Hualien Earthquakes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1854, https://doi.org/10.5194/egusphere-egu2020-1854, 2020.

The purpose of this study is to estimate maximum ground motions in northern Taiwan in the form of ShakeMaps as well as to assess potential human fatalities from a scenario earthquake on the Sanchiao active fault in this area. Analysis of seismic hazard potential becomes necessary in northern Taiwan for the Central Geological Survey (CGS) announced the Sanchiao active fault as Category II. The resultant ShakeMap patterns of maximum ground motion by using ground motion prediction equation (GMPE) method in a case of Mw6.88 show the areas of PGA above 400 gals are located in the regions inside the yellow lines in the corresponding figure. Furthermore, the areas of PGA greater than 637 gal are located in the northern Bali and the border area of Sinjhuang and Shulin. Likewise, the high PGV area greater than 60 cm/s are located in the border area of Sinjhuang, Taishan and Shulin. In addition, seismic hazards in terms of PGA and PGV in the vicinity of the Sanchiao fault are not completely dominated by the Sanchiao fault. The main reason is that some areas located in the vicinity of the Sanchiao fault are marked with low site response amplification values of 0.61 and 0.74 for PGA and PGV, respectively in northwestern Beitou. Finally, from estimation of potential human fatalities from scenario earthquakes on the Sanchiao active fault, it is noted that potential fatalities increase rapidly in people above age 45. Total fatalities reach a high peak in age groups of 55–64. Another to pay special attention by Taipei City Government is the number and percentage of fatalities above age 85 are more in Taipei City with values 419 and 8.54% than New than Taipei City with values of 319 and 5.02%. In addition, it is surprising that the number and percentage of fatalities are 1234 and 9.75%, respectively in Taoyuan City. Finally, the results of this paper will enable both local and central governments in Taiwan to take notice of potential earthquake threat in these areas, as well as to improve decision making with respect to emergency preparedness, response, and recovery activities for earthquakes in northern Taiwan.

How to cite: Liu, K.-S., Yan, M.-R., and Huang, Y.-H.: Estimation of seismic ground motions and attendant potential human fatalities from a scenario earthquake on the Sanchiao fault in northern Taiwan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-24, https://doi.org/10.5194/egusphere-egu2020-24, 2020.

The Aosta Valley Region territory (Italian Western Alps) is affected by a moderate historical seismicity. Nevertheless, in the last fifty years, the growth of the population and infrastructures have significantly increased the overall seismic vulnerability.

More in detail, the most vulnerable targets (international highways and the largest inhabited areas including almost 90% of the resident population), are concentrated in a narrow area along the main Dora Baltea Valley.

Therefore, moderate earthquakes with return times of about 100 years, could have important impacts on the regional economy.

Furthermore it has to be considered that, in areas marked by moderate seismicity, where potentially damaging earthquakes have long return times, the local authorities in charge of civil protection do not always seem to have a clear perception and a strong historical memory of the seismic risk.

To improve the general resilience towards the earthquake hazards, the Regional geological survey of the Aosta Valley Region has undertaken a process aimed at realization of an integrated and organic seismic risk management, financed by the EU on INTERREG ALCOTRA RISVAL project – Operational program Italy - France (Alps - ALCOTRA) 2014-2020.

All the planned activities have been mainly aimed to improve the geological knowledge already available, in order to achieve a clearer framework of the potential active tectonic structures (faults and thrusts), mapping the distribution and the geophysical properties of the quaternary deposits, which could potentially amplify the seismic waves.  

More in detail, seismic microzonation studies have been extensively perfomed along the main regional road axes, including over 100 geophysical tests. At the same time, two detailed studies have been made: the first  one regarding the potentially active fault "Aosta-Col di Joux-Ranzola" (located along the Dora Baltea Valley), the second one assessing the correlation between recent instrumental seismicity and active tectonic structures on the Italian side of the Mont Blanc Massif.

In a final step, a regional inventory of the seismic "strategic" buildings (hospitals, fire stations, town halls, ecc.) has been implemented

All the data have been integrated in the regional web portal, where the main geological, geotechnical and geophysical data of the Aosta Valley are already available. The inclusion of knowledge and data in a single web platform, which can be consulted online, improves the expected phenomena knowledge and its potential impacts on the territory, with a positive impact on the land management strategies and allowing the prioritization of costly structural reinforcements of buildings and infrastructures. In addition, the activities have been also conceived to support the regional civil protection authorities in the earthquake emergency planning activity, identifying the safest paths  the rescue teams and the first infrastructures structures to be controlled after a seismic event.

How to cite: Thuegaz, P., Pitet, L., and Bertolo, D.: An integrated approach to seismic risk management in a moderate seismicity alpine region , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3561, https://doi.org/10.5194/egusphere-egu2020-3561, 2020.

Throughout history, earthquakes have caused extensive damages in urban areas with important infrastructures and high population density. Especially, earthquakes have extensively damaged many regions of Central Asia (e.g., Tashkent in 1966, and Almaty in 1911). Hence, the estimation of the seismic hazard of the urban areas in Central Asia is very important due to the high level of seismicity in Central Asia and the rapid construction of new buildings. The high earthquake-induced damages in the cities often result from the local geological conditions and engineering properties of the soils that can produce significant site effects. Such seismic effects combined with the high vulnerability of buildings can result in extreme disasters during earthquakes. Therefore, geotechnical engineers/seismologists should decide to divide the city into specific microzones depending on their site effects and soil properties. However, conventional approaches in Central Asia have been proposed, based on (1) general engineering geological information; (2) the building code based on the estimates of the ground motions in terms of MSK-64 scale developed in 1978; and (3) the quantitative assessment only mapping and overlaying the data.

By characterizing the soft layers of their nature, thickness, and structure, and assessing the numerical model developed for the high-seismicity area of Central Asia, we can better assess specific site effects in each region of Central Asia. In addition, to predict the essential consequences of earthquakes, physically-based ground motion simulations should be developed by numerical simulations considering all possible processes of seismic wave propagation. Compared to empirical ground-motion predictions, numerical simulations of earthquake scenarios will provide much more flexible and better-suited solutions for most applications – especially those involving complex city environments. The ground-motion prediction equations or stochastic ground-motion estimates integrate characteristics of the earthquake source, path, attenuation, and site effects via approximate or statistical approaches. This method will provide rapid solutions that may be valid for a well-known context and would also be applied in Central Asia, for comparison with the numerical simulations. Finally, the quantitative approach for microzoning map incorporated with numerical simulation/site response analysis, for infrastructures (e.g., buildings, bridges, and dams) will be significantly useful in the future.

How to cite: Moon, S.-W., Hakimov, F., Kim, J., Reicherter, K., Havenith, H.-B., and Ischuk, A.: National Mitigation Strategy against Earthquakes in Central Asia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21202, https://doi.org/10.5194/egusphere-egu2020-21202, 2020.

 Earthquake is one of the most serious natural disasters for human survival. Once a destructive earthquake occurs, it often leads to huge losses. However, in the early days after the earthquake, it was difficult to quickly obtain disaster information due to the interruption of traffic, electricity, and communications. Therefore, damage assessment based on similarly historical cases rapidly in access to limited disaster data situation is effective support for analysis disaster and making disaster relief decision. In this study, earthquake disaster statistics with a magnitude of 4.0 or above and casualties in China from 2000 to 2013 were selected as historical cases. The number of earthquake casualties was used as an evaluation index, and the earthquake magnitude, focal depth and time of earthquake are selected as disaster indicators. A similarity assessment model based on Manhattan distance was used to evaluate the similarity of historical cases, and the collection of historical cases that participated in the assessment were screened.And then considering the spatial correlation between historical cases and current disasters, an earthquake disaster assessment model based on spatial reasoning of similarly historical cases would be established. Then the Yushu earthquake in Qinghai in 2010, the Lushan earthquake in Sichuan in 2013, and the Ludian earthquake in Yunnan in 2014 were selected as cases for accuracy verification by comparing the actual number of casualties. The result shows that: (1) For the three verification cases, the best evaluation accuracy of the  model is above 95%, indicating that the method has certain feasibility and applicability in the assessment of earthquake casualties;(2) The accuracy of the disaster assessment is related to the number of participating cases. When there are more than two participating cases, the accuracy of the model assessment decreases steadily with the increase in the number of participating cases. When the number of participating cases is 3 ~ 4, the evaluation accuracy of the model is the best. The method of this study is low cost, high efficiency, timeliness strong, simple, less constraints and easy to implement. It has certain practical value and promotion prospects in disaster assessment.

How to cite: Zeng, T., Gong, A., and Chen, Y.: Study on Assessment Method of Earthquake Casualties Based on Spatial Reasoning of Similarly Historical Cases, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6810, https://doi.org/10.5194/egusphere-egu2020-6810, 2020.

The pseudo-static approach has been conventionally applied for the design of gravity type quay walls. In this method, the seismic coefficient (k_h), expressed in terms of acceleration due to gravity, is used to convert the real dynamic behavior to an equivalent pseudo-static inertial force for seismic analysis and design. The existing k_h is simply defined as the expected peak ground acceleration (PGA) of the ground divided by the gravitational acceleration (g), which does not sufficiently reflect the real dynamic behavior. In order to improve the k_h definition, a number of studies have been performed for reducing the differences between pseudo-static and true dynamic behavior. In this regard, questions regarding the need for considering the effect of frequency characteristics of input earthquake, natural period of the backfill soil and the subsoil underneath the wall, and wall height on the deformation of quay wall crown (D_h) have been explored. In this study, dynamic centrifuge tests were conducted using the gravity type quay wall models designed with a k_h value of 0.13 to assess the behavior of the model wall during earthquakes. Three different variables: input earthquake motions, wall heights and the thickness of subsoil underneath the wall were considered, and the test results were compared and analyzed to assess the validity of the conventional k_h concept under these conditions. In addition, some improvements that should be considered for the future revision of the k_h definition are discussed.

How to cite: Lee, M.-G., Cho, H.-I., Sun, C.-G., and Kim, H.-S.: A study on the improvement of seismic coefficients for pseudo static analysis of gravity type quay wall via dynamic centrifuge tests, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4356, https://doi.org/10.5194/egusphere-egu2020-4356, 2020.

The awareness of earthquakes increased due to the occurrence of two large scale earthquakes in Gyeongju (M 5.8) and Pohang (M 5.4) earthquakes in Korea. The development of structural design standards is required to reduce structural damage caused by earthquakes. Current seismic analysis for the structural design requires maximum ground acceleration due to earthquakes, which will be influenced by the dynamic properties of the ground. In this study, the dynamic properties of the ground were improved by mixing cement and biopolymer solutions with soils, which will affect the dynamic properties of soils. Thus, the resonant column tests were performed to estimate the improved dynamic properties of soils, and equivalent linear response analysis was conducted to explore the maximum ground acceleration on the ground. Based on the new maximum ground acceleration on the improved soils, the safety of geo-structure was estimated. The results show that the improved soil using cement and biopolymers results in the increased safety factor of the geo-structure.

Acknowledgement 

This work is supported by the Korea Agency for Infrastructure Technology Advancement(KAIA) grant funded by the Ministry of Land, Infrastructure and Transport (Grant 20CTAP-C152100-02). Also, This research was supported by a grant(2018-MOIS31-009) from Fundamental Technology Development Program for Extreme Disaster Response funded by Korean Ministry of Interior and Safety(MOIS).

How to cite: Shin, S. W., Ahn, S. N., Ryou, J. E., and Jung, J.: Evaluation of dynamic properties and seismic performance of reinforced ground using renewable materials, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12832, https://doi.org/10.5194/egusphere-egu2020-12832, 2020.

The present study focuses on the area of ​​the Xerias torrent drainage basin, located at Northeastern Peloponnese, Greece. The study area is situated at the eastern part of the Gulf of Corinth, an active tectonic rift, characterized by high seismic activity and intense extension which is accommodated by a series of major active normal faults. As a result, it has frequently suffered damage from earthquakes which in some cases were accompanied by seismically-induced phenomena. These secondary phenomena include landslides and soil liquefaction and in some cases have the potential to cause more damage and casualties than the earthquake itself. Classic deterministic and probabilistic approaches of seismic hazard assessment do not account for seismically-induced phenomena and accordingly such analyses overlook areas prone to these secondary effects. The aim of our research is to evaluate seismic hazard not only as the hazard associated with the occurrence of potential earthquakes in the particular area, but also assess areas exposed to slope destabilization phenomena and soil liquefaction under seismic shaking. For this purpose we will use the pure statistical and the semi-statistical seismic hazard approaches along with the Analytic Hierarchy Process (AHP) to estimate the susceptibility of the study area to earthquakes and their triggering effects. AHP is a multi-criteria decision making method that helps to deal with a complex problem taking into account multiple conflicting criteria.  

Initially, we evaluated separately the hazard from earthquakes, seismically-induced landslides and soil liquefaction. Subsequently we stacked them into one single hazard map reflecting a holistic seismic hazard assessment. Initially, we estimated a hazard map associated merely with the seismic potential of the study area. In this context, we used a pure statistical and a semi-statistical approach by means of the extreme values method and the Cornell approach and estimated the spatial distribution of the maximum expected values of Peak Ground Acceleration (PGA) as well as Moment Magnitude for a return period of 475 years. These two data layers were inserted into the AHP along with information about the geological formations and the active faults of the study area, to produce the earthquake hazard assessment map. The map was produced using Geographic Information System (GIS), by applying weights and drawing a hierarchical structure to the sub-criteria of the above thematic layers. Next, we evaluated separately the earthquake-induced landslide hazard. For this purpose we incorporated into the AHP the parameters of the maximum expected values of Arias Intensity for a return period of 475 years, slope, lithology, aspect, distance to streams, distance to roads, landuse and topographic position index (tpi). Using GIS we produced a map depicting where earthquake-induced landslides are most likely to occur. Afterwards, we evaluated the soil liquefaction hazard adopting the same approach, using the parameters of compound topographic index (cti), type of soils, distance to streams and the magnitude weighted PGA. Finally, we stacked these three hazard maps and we classified the study area into four hazard levels corresponding to a complete seismic hazard map that accounts for earthquakes and for seismically-induced secondary effects.

How to cite: Karpouza, M., Chousianitis, K., Kaviris, G., Bathrellos, G., Skilodimou, H., Antonarakou, A., and Lekkas, E.: Seismic hazard assessment accounting for earthquake-induced phenomena through spatial multi-criteria analysis in Xerias torrent basin, Greece, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13999, https://doi.org/10.5194/egusphere-egu2020-13999, 2020.

The relationships between ground motion parameters (including peak ground acceleration, PGA; peak ground velocity, PGV) and building damages are crucial to estimate the possible seismic losses for future destructive earthquakes. One such relationship had been established based on the 1999 Chi-Chi earthquake (Mw=7.6). Since 2010, a new assessment system of seismic damaged buildings had been adopted in Taiwan. Damaged buildings are now classified into two categories, yellow-tagged buildings are amendable and red-tagged buildings may need to rebuild. Our main goal is to renew the relationship to better reflect the current status in Taiwan, both in the buildings and assessment system. 2016 Meinong earthquake (Mw=6.4) caused the most damaging buildings in Taiwan since 1999 Chi-Chi earthquake. It’s an opportunity to combine ground motion data with building assessments for the new regression relationship. From the results, we find out that in the Meinong earthquake, the PGA seems to possess a higher correlation to the building damages, contrary to the previous studies. Further investigation suggests that it may be due to the biased sample size to the damaged buildings, that is, most of the damaged buildings tend to be lower.

Keywords: Hazard analysis, Peak ground acceleration, Peak ground velocity, Seismic damage assessment

How to cite: Song, G.-Y. and Wu, Y.-M.: Relationships between ground motion parameters and damaged buildings for 2016 Mw 6.4 Meinong, Taiwan Earthquake, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2542, https://doi.org/10.5194/egusphere-egu2020-2542, 2020.

Earthquakes constitute a severe source of human disasters all around the world. However, one has to note, following the reviews on earthquake prediction, that at the present day no detectable, systematic and reliable precursory phenomena precede large earthquakes. Indeed, even if some precursory phenomena have been identified subsequent to many earthquakes, there are no statistically based reliable data for the recognition of a method based on the search for precursors. So, it’s necessary to make different prevention strategies to reduce the impact of disaster due to impending earthquakes in the region. The island of Taiwan is a product of the collision between the Philippine Sea plate and Eurasian plate which makes it a region of high seismicity. Active subduction zones occur south and east of Taiwan. Geochemical anomalies in soil gas and groundwater are commonly observed prior to impending earthquake and volcanic eruptions, attracting considerable attention in studies on precursory geochemical signals. Geochemical variations of soil-gas composition in the vicinity of geologic fault zone of Northeastern and Southwestern parts of Taiwan have been studied in detail recently. To carry out the investigation, temporal soil-gases variations are measured at continuous earthquake monitoring stations established along different faults. In present study, we have correlated observed soil-gas anomalies with some earthquakes magnitude ≥ 5 occurred in the region during the observation. The data is processed using a different kind of filters to reduce the noise level. It helps us to filter out the high-frequency noise and daily variation caused by different parameters. However, radon anomalies in all cases are not only controlled by seismic activity but also by meteorological parameters which make isolation of earthquake precursory signals complicated. Characteristics of temporal variability of soil-gas radon concentrations have also been examined using Singular Spectrum Analysis. Digital filter has been applied in eliminating the long term trend in the data and retains variations of less than 30 days. The radon variations exhibit dominant daily variations, which are controlled by atmospheric temperature inducted evaporation in surface water saturated soil (Capping Effect). The causal relationship is marked by a clear phase lag of 2-3 hours in the sense that peak in daily variation of radon succeeds the peak in temperature. Aperiodic variations in soil radon intensity in the range of 2-10 days are negatively correlated with temperature whereas positively correlated with pressure. To integrate our data with our working procedure, we use the popular and famous open source web application solution, AMP (Apache, MySQL, and PHP), creating a website that could effectively show and help us manage the real-time database. Based on the anomalous signatures from particular monitoring stations we are in a state to identify the area for impending earthquakes for the proposed tectonic based model for earthquake forecasting in Taiwan.

How to cite: Walia, V., Kumar, A., Fu, C.-C., Lin, S.-J., and Lin, C.-H.: Strategies for Earthquake Disaster Reduction Using Soil Radon Monitoring in Taiwan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12850, https://doi.org/10.5194/egusphere-egu2020-12850, 2020.

The Euphrates River is the main river running in Syria and the longest river in Western Asia and has three riparian countries, Iraq, Syria and Turkey. This research focuses on the Syrian part of the basin which makes 22% of total area of the basin.

Analyzing and evaluating the morphometric parameters is very important for understanding the nature of the surface and also for the sustainable territorial planning and management.

The goal of this study is to evaluate morphometric parameters and understand and analyze the nature of the terrain and determine the usability of the satellite images from Sentinel-2 for calculating the morphometric parameters and to compare their usability in the morphometric analysis with Digital Elevation Model.

Different morphometric characteristics have been generated in GIS environment and also remote sensing data (Sentinel-2 and Digital Elevation Model) have been applied used in this research and will be processed and analyzed using geospatial techniques.

The results allow the automated segmentation of the terrain based on derivatives of the input data. This division is compared to the typical land cover/land use of the various governorates in Syria.

As our study area is a long-lasting military conflict zone, this study will also help to better evaluate the river basin in Syria and to understand some practical problems related to the environment, including soil conservation and water conservation in term of irrigation land and drinking water supply which would also be affected by the armed conflict there.

How to cite: Naaouf, N. and Székely, B.: A study using multitemporal Sentinel-2 data and Digital Elevation Model for calculating morphometric parameters over the Euphrates River Basin in Syria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19902, https://doi.org/10.5194/egusphere-egu2020-19902, 2020.

Since 1970s, South Korea has been developed rapidly in the aspects of economy and industry over 40 years due to the Economic Development Plans led by the Korean government. Consequently, urbanization has been accelerated and the population then began to be flowed into major cities. In result, many parts of forestland in South Korea have been changed into urban areas by urban expansion and population migration under forestland conversion permission by South Korean Forestland Management Law. However, such permission standards cannot help being friendly to the development due to the line of national policy, and so several environmental problems, i.e., topographical and ecological changes, have been caused over couple of decades. In this study, therefore, we suggested new enhanced permission standards in terms of topographical and ecological protection in converted forestland. In Mountainous Districts Management Act of Korea Forest Service, slope and elevation criteria have been operated to regulate the indiscriminate use of risky land parcels when forestland is converted to other land use types. However, it is impossible to consider topographical variation with only such two indices in the land parcel because the indices values are averaged in each target parcel. Therefore, for supplementing insufficient criteria, the slope gradient by Catena was suggested by converted land use types. Furthermore, the ecological indices and criteria such as stand age, Diameter at Breast Height (DBH) and soil depth were considered in this study according to the forestland-watershed and –use types on converted target parcel. Firstly, we suggested flexible degree criteria by 14 land development types as topographical standards for forestland conversion. Secondly, the ratio of ‘risky slope’ below 40% in a target forestland parcel was defined to decrease the risk of disasters such as landslides. Thirdly, standard of ecological condition were proposed as ecological score by integrating stand age, DBH and soil depth classes in the target forestland parcels by 5 forestland-watershed and 14 land use types. As a result, we could prepare acceptable standards in South Korean that can reduce topographical and ecological damages by converting other land use type.

How to cite: Ha, S., Kwak, D., and Choi, J.: Study on Conversion Permission Standard based on Topographical and Ecological Indices in South Korea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6563, https://doi.org/10.5194/egusphere-egu2020-6563, 2020.

With the rise of urbanization in China, the damage of natural disasters was getting worse. As one of the most important cataclysms, typhoon “Lekima”, “Hato”, “Mangkhut”, “Rammasun” effect on coastal region in China significantly. In view of contingency management, typhoon cataclysm may lead to the public crisis. This crisis accompanies particularly heavy loss and profound effect, and often associated with regional emergency capability.
How to identify the crisis from a coming tropical cyclone? When to give an early warning to decision-making department depends on the regional emergency capability? These valuable questions are remaining uncertain. 
For the purpose of answering these key questions, we research on disaster mechanism and case analysis of tropical cyclones. These researches help us to build the identification indicator of crisis and determine the threshold on society, economic, environment and Public sentiment, which are helpful for the emergency response and crisis management of tropical cyclone disaster.

How to cite: Zhang, W.: Identification of public crisis from typhoon cataclysm and its threshold research, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12384, https://doi.org/10.5194/egusphere-egu2020-12384, 2020.

Road damage in plateau mountainous areas has a significant impact on emergency rescue, and the size of the area where emergency rescue vehicle teams travel at different rescue stages is different, which also gives rise to different considerations of road demand. Current research finds that the respective characteristics of Dijkstra's algorithm and ant colony algorithm can meet the different needs of emergency rescue vehicle teams when they are traveling at different regional sizes. Therefore, the article simulates the earthquake and calculates the road accessibility results after the earthquake, and then considers the differences in road demand and considers the size of different regions, the Dijkstra algorithm and the ant colony algorithm are used respectively to plan the overall emergency rescue plan by setting different scenarios. The results show that the emergency rescue-planning route in different scenarios provided by the plan is scientific and reasonable, and can provide support in the research of key links.

How to cite: Li, J.: Research on emergency rescue plan of plateau area after earthquake based on road accessibility, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7666, https://doi.org/10.5194/egusphere-egu2020-7666, 2020.