This session is devoted to the advancement of methods and techniques that may contribute to the compilation, storage and elaboration of impact data sets useful for the intensity characterization of historical earthquakes as well as for seismic hazard and risk assessment purposes. Welcomed to this session are also similar studies focusing on the collection and elaboration of impact data sets for other earthquake-related natural hazards, e.g. tsunamis and landslides, with the aim to help the assessment of hazards and risks.
Orals: Fri, 2 May | Room 0.96/97
The 1 January 2024 Mw7.5 Noto Peninsula earthquake generated a tsunami that spread across the East Sea (Sea of Japan). We investigate the tsunami effect on the coast in regional distances using tsunami-induced seismic wavetrains recorded by borehole broadband seismometers in the Korean Peninsula. The tsunami-induced seismic wavetrains are observed in the seismic stations near the coast. The seismic wavetrains are consistent with the tsunami records in tide gauges. The shared features in waveforms and spectral contents between the tsunami waves and the tsunami-induced seismic signals suggest that the energy origins are the same. The coastal loading of the tsunami induces ground tilting around the coast, producing long-period horizontal wavetrains that are polarized in coastline-perpendicular directions. The long-period tsunami-induced seismic energy deform the medium dynamically. Tsunami-induced deformation decreases with distance from the coast, being effective up to some depths. The amplitudes of tsunami-induced seismic signals are proportional to the amplitudes of tsunami waves. The tsunami-induced dynamic stress change reaches 0.81 kPa on the coast. A large runup height of a tsunami may trigger earthquakes around the coast.
How to cite: Hong, T.-K., Kim, B., Lee, J., Park, S., and Lee, J.: Coastal-medium deformation and seismic hazards induced by the 2024 Noto Peninsula earthquake tsunami, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7608, https://doi.org/10.5194/egusphere-egu25-7608, 2025.
The tsunami earthquake earthquake occurred on 25 of October 2010 in the Indian Ocean about 79 km south-west of Mentawai islands. The tsunami caused severe damage and claimed many victims in some coastal villages. The main purpose of the survey was to measure the inundation and the run-up values as well as to ascertain the possible morphological changes caused by the wave attacks. Attention was particularly focussed on the most affected villages, that is Muntei Barubaru and Malakopak in Mentawai islands. The most severe damage was observed in the Muntei Barubaru. Most places were hit by three significant waves with documented wave height often exceeding 5 m. The maximum runup value (17.00 m) was measured at North Pagai, where also the most impressive erosion phenomena could be found.
How to cite: Julius, A. M., Priadi, R., Anugrah, S. D., Alfahmi, F., and Kuncoro, . K.: Brief Account of the Post-event survey 2010 Pagai-Mentawai islands tsunami earthquake in Indonesia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1361, https://doi.org/10.5194/egusphere-egu25-1361, 2025.
The extremely shallow location of the seismogenic megathrust in the western Solomons and the existence of significant island land area on the upper plate overlying the seismogenic zone enables us to use corals to obtain vertical motion history closer to the trench and lower plate than anywhere else in the world. In addition, coral paleogeodesy on Porites microatolls acting as long-term vertical positioning station may provide a relative sea level (RSL) change record spanning hundreds of years. Our goal is to develop a centennial record of sea level change and vertical tectonics from multiple Porites microatolls. By isolating the RSL record common to each microatolls, we can then derive a vertical tectonic record by removing the RSL variations from the raw time series recorded by the microatolls. To achieve that goal, we present recent work combining coral paleogedesy, annual δ13C record and modeling of coral morphology over the last 80 years in the western Solomons. The steps to obtain a long-term record of sea level change and vertical tectonics on samples of a ~80 year old Porites head collected in 2013 after the 2007 Mw 8.1 earthquake. We sampled the coral over 2 to 3 annual bands every ~2 months at various depths and times, performed a stable isotope analysis on each sample, cross-correlated each record and plotted the variation in δ13C versus water depth. Linear regressions show that the variation in accumulated δ13C as a function of water depth relative to the coral’s top water depth is 41 cm/‰ with a R2 coefficient of 0.98. We the sampled bimonthly stable isotopes along 80 annual bands. The span of each year is determined from correlating the annual banding and the seasonal cycles in δ13C and δ18O. Applying the linear relationship to the δ13C generates a raw record of relative sea level change. We then use the monthly tide gauge record in Honiara (Guadalcanal) to remove the effects of regional sea level change to the RSL time series obtain from the coral. The result is a record of the vertical tectonic motion of part of the Western Solomon before and after the Mw8.1 2007 earthquake. We analyze the results in terms of the yearly vertical record of the seismic cycle. Current geodetic records at subduction zones constrain at most deformation during one earthquake cycle while multiple earthquake cycles are needed to robustly constrain the physical state of a megathrust. We hope to be able to extend the coral paleogeodetic record in the Weatern Solomons over several hundred years over multiple seismic cycles. This would represent a critical data gap that hampers our understanding of subduction physics and our ability to forecast earthquakes.
How to cite: Karaesmen, M. E., Lavier, L., and Taylor, F.: Decadal to Centennial Vertical Paleogeodetic Record of the Seismic Cycle in the Western Solomons from Coral Paleogeodesy and Stable Isotopes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16187, https://doi.org/10.5194/egusphere-egu25-16187, 2025.
We present an overview of the inversions performed with the KF method (Pettenati and Sirovich 2003; Sirovich and Pettenati 2004) on some historical earthquakes in the CPTI15 catalogue data domain. This method is based on a kinematic function (KF) that is controlled during the inversion by the Genetic Algorithm with Niching's Variant (NGA) algorithm (Gentile et al. 2004).
Since we are dealing with historical earthquakes, a distinction is first made between instrumental and pre-instrumental earthquakes. For the former between 1900 and 2009 a quantitative assessment is made, for the latter only qualitative assessments can be made. We present statistics to evaluate the magnitude and epicentral coordinates obtained from KF with instrumental data or the parameters of the CPTI15 catalogue. To evaluate the fault plane solutions, we instead used the disorientation angles with the instrumental focal mechanisms (Sirovich et al. 2013). In the case of pre-instrumental earthquakes, the assessments vary from case to case. From the comparison of the results obtained with techniques based on the conversion of strong motion data into intensity, statistical analysis or comparison with the seismotectonic of the area could be made.
References
Gentile, F., F., Pettenati and Sirovich, L.; 2004. Validation of the Automatic Nonlinear Source Inversion of the U. S. Geological Survey Intensities of the Whittier Narrows, 1987 Earthquake. Bull. Seism. Soc. Am., vol.94, No.5, 1737-1747, October 2004, https://doi.org/10.1785/012003157.
Pettenati, F., and Sirovich, L.; 2003. Test of Source-Parameter Inversion of the USGS Intensities of the Whittier Narrows, 1987 earthquake. Bull. Seism. Soc. Am, vol.93, No.1, 47-60, February 2003, https://doi.org/10.1785/0120010113.
Sirovich, L. and. Pettenati, F; 2004. Source Inversion of Intensity patterns of Earthquakes; a Destructive Shock in 1936 in northeast Italy. Journal of Geophysical Research, vol. 109, B10309, 2004, 1-16, https://doi.org/10.1029/2003JB002919.
How to cite: Pettenati, F.: The KF-NGA technique for the inversion of macroseismic data. Summary of the solutions obtained from the CPTI15 catalogue data., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16200, https://doi.org/10.5194/egusphere-egu25-16200, 2025.
The assessment of ground shaking at high spatial resolution after a recent or future earthquake is crucial for rapid impact assessment and risk management. This is even more important in the urban context, where small-scale differences can have a significant effect on the impact of the earthquake on people and property. Classical seismological networks, however, are usually too sparse to capture the variability of ground shaking at high spatial resolution. In this paper, we show how a multivariate spatial statistical model can be used to improve ShakeMaps by integrating station data (e.g. peak ground accelerations), data from citizen science initiatives (e.g. smartphone accelerations and felt reports), and macroseismic data. The statistical model accounts for the heterogeneity of the data sources in terms of spatial density, measurement uncertainty and bias. The model achieves data fusion without the need for calibration relationships and co-located information, and provides the ShakeMap uncertainty in a natural way.
Our approach is applied to events measured by a seismological network and by the smartphones of the Earthquake Network citizen science initiative, and for which felt reports from the LastQuake app of the European-Mediterranean Seismological Centre and macroseismic information by the Italian National Institute of Geophysics and Volcanology are available.
How to cite: Finazzi, F., Bossu, R., Cotton, F., Filote Pandelea, S. M., and Vannucci, G.: Enhancing ShakeMaps using crowdsourced smartphone data and macroseismic information through spatial statistical modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11406, https://doi.org/10.5194/egusphere-egu25-11406, 2025.
Predicting large earthquakes remains a complex and critical challenge in seismology. This study investigates distinctive seismic precursors by analyzing unique waveform patterns in foreshock sequences. Using the 2011 Mw9.1 Tohoku earthquake as a case study, preceded by a Mw7.3 foreshock, we identified an anomalous sawtooth pattern in the ground velocity envelope following the foreshock. Unlike typical post-earthquake recordings, this pattern is interpreted as evidence of the locked state of the mainshock fault, which suppresses the foreshock’s ability to trigger aftershocks.
To quantify these waveform anomalies, we developed the index Q based on the first 45 minutes of waveform recordings. Applying this method to 75 Mw6+ earthquakes recorded globally since 2010, our approach correctly identified 10 out of 11 foreshock sequences that preceded larger earthquakes within 10 days. Only 7 out of 64 remaining earthquakes were misclassified, highlighting the robustness of the method.
Our findings suggest that these sawtooth patterns are reliable indicators of impending large earthquakes, offering a novel tool for seismic forecasting. By integrating this method with other geodetic and seismological datasets, we aim to enhance hazard assessment and mitigation strategies, contributing to improved preparedness for future seismic events.
References
1Lippiello, E., Petrillo, G., Godano, C., Tramelli, A., Papadimitriou, E., & Karakostas, V. (2019). Forecasting of the first hour aftershocks by means of the perceived magnitude. Nature communications, 10(1), 2953.
How to cite: Petrillo, G., Lippiello, E., Dal Zilio, L., and Godano, C.: Quantifying Foreshock Anomalies: Insights from Envelope Waveforms, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14111, https://doi.org/10.5194/egusphere-egu25-14111, 2025.
Eastern Part of the Czech Republic in the Outer Western Carpathians (OWC), particularly the Javorníky Mts. range along the Czech-Slovakian border, has been traditionally considered a geologically stable region with documented low contemporary seismic activity. However, recent geomorphological analyses and field investigations reveal compelling evidence of prehistoric large-scale and highly mobile mass movements, potentially triggered by paleo-earthquakes. This study integrates high-resolution LiDAR mapping, field investigations and trenching, geophysical surveys, radiometric dating, and numerical modeling to reconstruct the paleo-seismic characteristic of the region.
We identified those paleo-landslide features using high-resolution LiDAR data and assumed their relationship to past seismic activity by their close vicinity to a Holocene polyphase surface rupture of the Lidečko Fault. LiDAR mapping combined with the Electrical Resistivity Tomography (ERT) analyses provide valuable insights into the structural geology, lithology, failure mechanisms of paleo-landslides. Trenching and dating techniques, including radiocarbon and optically stimulated luminescence (OSL), help establish the timing of these events and their possible seismic triggers. Structural analysis of the Lidečko revealed the active strike-slip and oblique reverse kinematics with surface ruptures and liquefaction features, supporting the hypothesis of the landslides´ earthquake-induced origin.
Distinct three generations of landslides were identified as half-ellipsoidal depleted source zones about 400 m long, 200 wide and about 25 m deep with remnants of their accumulations at the toe and in the valley floor and different state of subsequent reworking by shallow slope processes. The fluidized mass was displaced for up to 1 km, of which up to 600 meters comprised totally flat riverbed. Radiometric dating of associated landslide-dam deposits revealed the landslides´ ages about 91 ka, 45 ka and 1.8 ka ago.
To accurately assess their potential coseismic origin, synthetic seismic acceleration data derived from waveform records in the OWC region is integrated into both Newmark Displacement Analysis (NDA) with the Velocity-Dependent Friction Law (VDFL) and the distinct element numerical modeling. This combined approach improves the simulation of rock mass and landslide dynamics under seismic loading conditions and ensures a more precise analysis of earthquake-induced slope processes. Specifically, PFC3D numerical modeling is employed to reconstruct the paleo-topography and simulate the long run-out behavior of paleo-landslides under various earthquake scenarios. These simulations provide deeper insights into the triggering mechanisms and movement patterns of such landslides.
The estimated magnitudes of past earthquakes challenge assumptions about the OWC's seismic stability and suggest significant unrecorded events. This study improves understanding of earthquake-induced landslides in stable regions and offers a framework for assessing long-term seismic hazards. The methods used can be applied to other areas with uncertain seismic histories, helping to better understand the connection between tectonics and landscape evolution.
The research was funded by the Grant Agency of the Czech Republic (GC22-24206J) and Taiwanese National Technological and Science Council (MOST/NTSC 111-2923-M-008-006-MY3).
How to cite: Nguyễn, T.-T., Baroň, I., Dong, J.-J., Melichar, R., Hartvich, F., Klimeš, J., Černý, J., Šutjak, M., Kociánová, L., Dušek, V., Rowberry, M., Braucher, R., Goslar, T., Tseng, C.-H., Chen, Y.-C., Lin, C.-H., and Gao, J.-Q.: Revealing Hidden Seismic Histories: Prehistoric Landslides as Indicators of Paleo-Earthquakes in the Outer Western Carpathians, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15884, https://doi.org/10.5194/egusphere-egu25-15884, 2025.
We know more about earthquake processes, vulnerability modelling and characterization of the built environment than ever before. Yet, earthquake losses and casualties continue to increase, even in countries where modern seismic design regulations have been introduced decades ago. In this study we investigate the drivers of earthquake damage and losses using the global seismic hazard and risk model developed by the Global Earthquake Model (GEM) Foundation and its partners, as well as data from fatal earthquakes since 1950. We isolate specific parameters that can influence the severity of the ground shaking, the vulnerability of the building stock, and the spatial distribution of the population. These include the prevalence of soft soils, the average seismic hazard in each country, the likelihood of experiencing extreme ground shaking, the occurrence of earthquake-triggered hazards (i.e., liquefaction, landslides and tsunamis), the time of the event, the proximity of megacities to active faults, the percentage of specific types of construction, and some socio-economic factors. We compare these underlying parameters and the estimated or observed seismic risk between different countries and identify specific patterns that systematically exacerbate the overall impact. We observe that high economic losses are frequent in countries with well-established seismic regulations not only due to the high replacement/repair costs, but also due to the high prevalence of commercial and industrial facilities and complex infrastructure. On the other hand, high fatality risk is frequent in countries whose building stock is comprised of non-engineered buildings with heavy roofs and floors. Another relevant observation is that although ground shaking is overwhelmingly the main cause of damages and losses, under specific geological and demographic conditions, the impact of tsunamis, landslides and liquefaction phenomena can be devastating. Lessons drawn from these observations and patterns can be useful to understand how the impact of earthquakes can be better assessed, reduced, and managed.
How to cite: Silva, V., Aljawhari, K., Baiguera, M., Calderón, A., Caruso, M., Costa, C., González González, D., Nafeh, A. M. B., Rao, A., Yepes, C., and Karimzadeh, Z.: Drivers of Earthquake Damage and Losses: a Global Perspective on Where and Why Seismic Risk is High, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21102, https://doi.org/10.5194/egusphere-egu25-21102, 2025.
In order to interpret geological risk assessment for Earthquake hazard by mapping work, since geotechnical and geologic feature of each country is different, it is necessary to objectify or classify quantitativel geological risk evaluation in accordance with Korean rock mass characteristics.
It could be summarized major categories of geological risk factors by locally geological features as thickness of soil over the rocks, geologic structure, rock mass characteristics, hydrogeology, high stress, and ground characteristics.
Induced main factors that could be evaluated and predicted Earthquake hazard risk through literature investigation and analysis study on research trend related to the Earthquake map engineering around the world. The final 15 risk factors were derived by considering the geological and geotechnical characteristics of Korea from the 40 or so preliminary extracted risk factors. The 15 risk factors are classified into 4 main categories and 1 additional category.
Among the five main categories, the geologic structure category are risk factors classified into faults and fracture zones, strike and dip of discontinuity, and dikes. Rock mass characteristics categories are risk factors classified into rock type, discontinuity roughness, RQD, uniaxial compressive strength of rock, and anisotropy. Hydrogeological categories are risk factors classified into groundwater level fluctuations, and permeability coefficients. The load category is the risk factor classified by the thickness of the soil above the rocks. The additional categories are risk factors classified into whether there is a karst topography, earthquake history, and ground displacement area.
How to cite: Myeong Hyeok, I.: Case Study of Geological Risk Factors for Earthquake Hazard Mapping in the South Eastern Korea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2445, https://doi.org/10.5194/egusphere-egu25-2445, 2025.
A Ms 6.8 earthquake struck Luding, China, in September 2022, causing significant structural damages to buildings. Notably, reinforced concrete (RC) frame structures exhibited the failure mode of strong beam–weak column (SBWC), which poses a severe threat to human safety and economic stability. This study investigates the disadvantageous failure mechanisms in RC frame structures, drawing on observations from the author's recent field investigations. Refined finite element models (FEMs) of RC frames were developed to systematically simulate these failure mechanisms. The models enabled an in-depth analysis of structural characteristics, with particular attention to column-to-beam flexural strength ratios (CBFSRs). These ratios were calculated to identify thresholds that can prevent destructive SBWC failure modes and promote the desired strong column–weak beam (SCWB) behavior. The FEM analysis results were validated against real-world earthquake damage phenomena, showing strong consistency in damage patterns. The study also highlights the critical role of external factors in exacerbating structural damage. For example, slope site effects significantly amplified seismic impacts on structures. Furthermore, the influence of non-structural elements such as Que Ti and infill walls was found to increase shear force demands on RC frame columns, further compromising their performance under seismic loads. Based on these findings, the study proposes an optimal range for CBFSRs to achieve SCWB behavior, contributing to safer structural designs. Practical recommendations and considerations are outlined to guide future earthquake-resistant construction practices and mitigate disaster risks effectively.
How to cite: Zhu, B., Zhang, L., and Li, N.: Damage Analysis of RC Frames in the Luding Ms 6.8 Earthquake, China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6093, https://doi.org/10.5194/egusphere-egu25-6093, 2025.
The Belìce Valley is located in the western part of Sicily, shared between the territories of the three former provinces of Palermo, Trapani, and Agrigento (Italy). At 2.01.09 (GMT) on 15 January 1968, this area of western Sicily was hit by a 6.41 Mw earthquake. This seismic event caused about 370 deaths and severe damage to 14 villages, four of these (Gibellina, Poggioreale, Salaparuta and Montevago) were completely destroyed. The stark reality of the destruction of entire urban settlements followed by the top-down rewriting of the local identities induced 1 ) a generalized de-territorialization as a strategy of the government bodies aimed to facilitate the population decrease in the Belìce Valley and 2) the foundation of new cities, such as the “new” Gibellina (about 10 km from the original site and rebuilt in a part of the village of Salemi territory), the “new” Poggioreale (3 km away from the original site) and the “new” Salaparuta (also 3 km away from the original site), to which it is possible to add Montevago.
In this work we attempt an innovative way of reading the legacy of that dramatic event based on a double-sided approach: 1) an analysis of the deterritorialization and reterritorialization process based on a geoeconomic approach and 2) a detailed framing, through special geovisual tools, of the paths of the regeneration process to verify whether the “new” interaction between humans and nature has reached an adequate level. We address the technical issue of rephotography as a powerful and rapid method to observe the changes or territorial stasis following the earthquake. This approach is based on the collection of historical photographs and, subsequently, on-site activities for the creation of a contemporary archive of images. This double analysis introduces us to a new perspective where, in our opinion, it is possible to frame some characteristics of the Belìce Valley and some more general aspects useful for other territories affected by destructive events and that must face choices regarding the future of their communities.
How to cite: Mattia, M., Petino, G., and Napoli, M. D.: The 1968 Earthquake in Belìce Valley (Sicily, Italy): Evolution of a human and natural landscape as a tool for a backward analysis of a rebuilding process in a rural area., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7067, https://doi.org/10.5194/egusphere-egu25-7067, 2025.
Seismic activity is a fundamental characteristic of tectonically active regions, and Sicily represents a key area for understanding seismic processes in the Mediterranean. This study presents a comprehensive survey of seismic activity in Sicily using the Epidemic-Type Aftershock Sequence (ETAS) method and a detailed analysis of the magnitude of completeness (Mc). By integrating these two approaches, we aim to enhance our understanding of seismicity patterns and assess the seismic hazard in the region.
The ETAS model, widely used in seismology, enables the separation of background seismicity from earthquake clusters, such as aftershocks and swarms. We employed this method to model seismic events recorded in Sicily over a multi-year period, using data from local and regional seismic networks. By estimating key ETAS parameters, including productivity, aftershock decay rate, and spatial clustering, we provide insights into the temporal and spatial distribution of seismicity. Our analysis reveals significant variability in seismic clustering across different tectonic domains in Sicily, reflecting the complex interplay of crustal structures and active fault systems.
In parallel, the Mc was evaluated to determine the reliability of the seismic catalog used. The Mc defines the lowest magnitude at which all earthquakes in a given dataset are reliably detected, making it a critical parameter for seismic hazard assessment. Through statistical techniques such as the maximum curvature method and goodness-of-fit tests, we assessed Mc spatially and temporally. Results indicate that Mc varies significantly across the region, influenced by factors such as network density, station sensitivity, and local noise conditions. Areas with lower Mc values, such as the eastern coast near Mount Etna, provide a higher resolution of seismic activity compared to regions with sparser network coverage.
By combining ETAS modeling with Mc analysis, this study highlights the importance of comprehensive seismic monitoring in seismically active regions like Sicily. Our findings show that the seismicity is highly influenced by the region’s tectonic complexity, which includes the convergence of the African and Eurasian plates, active subduction processes, and the dynamic volcanic activity of Mount Etna. These factors contribute to the heterogeneous distribution of seismicity and underscore the need for tailored monitoring and modeling strategies.
The results have important implications for seismic hazard assessment in Sicily. The ETAS model allows for the probabilistic forecasting of aftershock sequences. Additionally, understanding Mc distribution enhances the reliability of seismic catalogs, which are fundamental for evaluating seismic risk and improving earthquake preparedness.
In conclusion, this study demonstrates the utility of combining the ETAS method with Mc analysis to achieve a deeper understanding of seismic activity in Sicily. The integration of these methodologies not only refines the characterization of seismicity but also provides actionable insights for regional seismic hazard mitigation efforts.
How to cite: Figlioli, A., Cilluffo, G., Martorana, R., Vitale, G., and D'Alessandro, A.: Seismic Monitoring in Sicily: Insights from ETAS and Magnitude of Completeness Approaches, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10899, https://doi.org/10.5194/egusphere-egu25-10899, 2025.
Among the natural disasters that occurred in Europe in modern times, the earthquakes of February and March 1783 are certainly the most well-known and studied. This is due to their vast European resonance, the wealth of documentary material produced about the event, and the complexity and audacity of the recovery plan for the province developed by the Neapolitan government authorities. The seismic sequence is currently reported in seismic catalogs with five main shocks occurring between February 5 and March 28, 1783, with magnitudes ranging between 5.1 and 7.1. Despite the wealth of documentary evidence and the extensive scholarly literature that has emerged, significant gaps remain in our understanding of this seismic sequence. These limitations arise primarily from the inherent challenge of distinguishing between the effects of individual earthquakes and assessing the cumulative impact of successive shocks (Stucchi and Rovida, 2008; Guidoboni and Valensise, 2015; Tertulliani et al., 2018). Therefore, a long-term study was undertaken to re-examine what was already known, starting from existing sources, and to enrich the documentary heritage through new basic research, with the aim of increasing the number of macroseismic observations. This work presents the analysis of information relating to approximately 565 localities, based on a hypothetical chronological reconstruction of the sequence's shocks, which takes into account the impact of cumulative damage caused by multiple shocks when assigning macroseismic intensity. Through this approach, the shocks already present in the catalogs were reconstructed as faithfully as possible, using a richer knowledge framework compared to the past. The assignment of macroseismic intensities, according to the MCS and EMS-98 scales, has allowed for the construction of a new and broader macroseismic dataset and the proposal of a new interpretation of the sequence, highlighting the problems connected to the assignment of intensities.
How to cite: Orlando, M., Tertulliani, A., and Graziani, L.: Macroseismic re-appraisal of the 1783 Calabria seismic sequence, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11532, https://doi.org/10.5194/egusphere-egu25-11532, 2025.
The 4 February 1867 earthquake is the largest in the Ionian Islands and one of the largest in the Eastern Mediterranean. However, it remained until recently one of the least studied historical events. In order to highlight its characteristics and impact we reevaluated existing knowledge and used new contemporary and modern sources.
The reevaluated sources included contemporary scientific reports and descriptions of local writers, while the newly utilized sources comprised contemporary local and national newspapers, additional reports from scientists and local writers, ecclesiastical chronicles, and modern sources such as scientific books, works by local authors, and local and national journals. The extracted information focused on: (i) the seismological parameters, (ii) the impact on the local population, (iii) the damage to buildings, and (iv) the earthquake environmental effects (EEEs).
The first category included the origin time and duration of the main shock, the epicenter location, precursors, and aftershocks, among other details. The impact on the population encompassed both the direct and indirect effects of the main shock, including the emergence of infectious diseases, as well as the demographic evolution in the following years. Regarding the building stock, the dominant building types were identified, along with the type, extent, and distribution of damage observed in villages and towns. The EEEs comprised ground cracks, landslides, liquefaction, hydrological anomalies, and sea disturbances, including a mild tsunami.
Based on the provided information, it is concluded that the affected residential areas were located within specific zones predominantly composed of post-alpine deposits and, to a lesser extent, alpine formations, both characterized by mechanical properties that render them susceptible to earthquake-triggered failures. Furthermore, the EEEs occurred in zones with high susceptibility to such phenomena, supported by a rich history of previous and subsequent occurrences. The available quantitative and qualitative data allowed for the application of the European Macroseismic Scale 1998 (EMS-98) and the Environmental Seismic Intensity Scale (ESI-07), facilitating a comparison of results and intensity distributions. This analysis highlighted the most affected fault blocks and identified the factors controlling their distribution.
This research has not only highlighted the benefits of utilizing such sources and information for reconstructing a historical destructive earthquake, but it has also demonstrated that independent sources remain to be explored and new perspectives could still provide valuable insights into historical earthquakes. Moreover, this study underscores that understanding the past seismicity of the Ionian Islands, as well as other seismically active regions worldwide, remains an open challenge for the global scientific community.
How to cite: Mavroulis, S., Mavrouli, M., and Lekkas, E.: Reappraisal of the 4 February 1867 Ionian Sea (Western Greece) earthquake and its impact on the environment, structures and public health, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12713, https://doi.org/10.5194/egusphere-egu25-12713, 2025.
Earthquakes originating near Earth’s surface pose significant hazards to human safety and infrastructure, as their associated surface deformation can result in widespread structural damage and loss of life. Improved characterization of surface deformation patterns and extents associated with shallow earthquakes–when paired with knowledge of the earthquake epicenter and magnitude–can provide critical insight into earthquake mechanisms, surface rupture processes, and aid in determination of damage proxy extents for disaster response and mitigation efforts. Spaceborne synthetic aperture radar (SAR) interferometry (InSAR), as well as pixel offset tracking of both SAR and optical imagery, can provide detailed measures of surface deformation occurring during an earthquake (i.e., “coseismic deformation”). The Advanced Rapid Imaging and Analysis (ARIA) project at the NASA Jet Propulsion Laboratory is currently developing a global archive of accessible, standardized, and analysis-ready coseismic displacement products derived from spaceborne SAR and optical datasets to facilitate more comprehensive studies of earthquake rupture processes and improve estimates for downstream rapid response efforts. Our product archive is unique from existing coseismic displacement product databases in terms of the data available, format, and accessibility. Our 30-meter resolution products are designed to be sensor-agnostic and are provided in standardized units and format for rapid integration into existing GIS platforms and modeling workflows with lower latency due to greater source data availability. Additionally, correction layers for solid-earth tides, ionospheric, and tropospheric propagation path delays are embedded with the analysis-ready products for the end-user. Integration of both SAR and optical datasets provide increased sensitivity to surface displacement via pixel offset tracking. Our workflow leverages the existing ARIA-HyP3 framework and capabilities to cost-effectively generate coseismic products in the cloud for the historic record of Sentinel-1 data availability (2014 - present), as well as for future large magnitude, shallow earthquake events meeting predefined significance thresholds. For these future events, our workflow will be automatically triggered and the resultant coseismic displacement products will be made available with low latency (<24 hours after source SAR/optical data are made available) to provide information about surface deformation and damage extents caused by the earthquake. In this presentation, we will demonstrate the product generation workflow and capabilities, as well as examples of earthquake science use-case and disaster response applications that showcase the advantages of our automated, standardized, and sensor-agnostic coseismic displacement products.
How to cite: Speed, C., Bato, M. G., Sangha, S., Marshak, C., Kennedy, J., Melgar Moctezuma, D., Solares, M., Bekaert, D., and Fielding, E.: A global archive of accessible, analysis-ready coseismic displacement products for earthquake science applications derived from SAR and optical datasets, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16216, https://doi.org/10.5194/egusphere-egu25-16216, 2025.
Aquatic environments, particularly coastal lakes and lagoons, offer optimal conditions for preserving depositional records of past tsunami events. Tsunamis are known to transport sediments from shallow nearshore areas and sand spits, redepositing them in lagoon environments. This study investigates the geochemical signatures of historical Eastern Mediterranean tsunamis in two lagoons along the southern coast of Türkiye: Ölüdeniz and Demre lagoons. A total of nine piston cores, ranging from 3.5 to 4.0 meters in length, were analyzed using an ITRAX micro-XRF scanner to obtain high-resolution radiographic and optical images, as well as detailed elemental composition of the sediments. In Ölüdeniz, an oligotrophic lagoon, sedimentary events exhibiting distinct [Ti, Fe, Zn]/Ca anomalies temporally correlate with historical tsunamis. These anomalies are attributed to a sudden influx of sediment from the land into the lagoon, likely originating from the lagoon's sand spit. In contrast, in the hypersaline Demre Lagoon, tsunami deposits are characterized by sediments with lower concentrations of Sr, Cl, and Br compared to the background sedimentation. Due to the lagoon's hypersaline conditions, bio/chemical carbonate and detrital siliciclastic deposition are typically accompanied by salt deposition, which serves as the primary source of Cl and Br in the sediments. However, during the rapid deposition of tsunami sediments, there is insufficient time for salt deposition, resulting in the depletion of Cl, Br, and Sr in these layers. This study in Ölüdeniz and Demre lagoons confirms that lagoons are excellent sites for paleotsunami research.
How to cite: Avşar, U., Şen, S., and Yeniçeri, M. T.: Geochemical Signatures of Historical Eastern Mediterranean Tsunamis Preserved in Lagoon Sedimentary Sequences, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19552, https://doi.org/10.5194/egusphere-egu25-19552, 2025.
The investigation of historical seismicity has increasingly demonstrated its pivotal role in advancing seismic hazard and risk assessment. This study presents an integrated methodological approach to recover and analyze analog seismograms, aiming to enhance our understanding of historical earthquakes and their implications for local and regional seismotectonic modeling. Our work focuses on three seismic events occurred in southern Italy: the 1947 Squillace Basin earthquake, the 1968 Belice sequence, and the 1978 Ferruzzano earthquake. These events, located within the geodynamically complex and high-seismic-risk Southern Italy region, represent significant case studies to test the potential of analog seismograms in providing past earthquake characterizations. For each event, we employed a systematic workflow encompassing the selection, digitization, and processing of analog seismograms. The instrument corrections were rigorously applied, and data quality was assessed to ensure reliable results. A time-domain waveform inversion algorithm specifically tailored for pre-digital data was utilized to compute moment tensor solutions. This approach allowed us to determine key seismic parameters, including fault mechanisms, hypocenter locations, and moment magnitudes, offering new insights into the seismotectonic framework of this region. The 1947 Squillace Basin earthquake was identified as a Mw 5.1 event with left-lateral kinematics on a WNW-ESE fault, consistent with STEP fault activity of the Northern Calabria subduction edge. Similarly, the 1968 Belice sequence revealed predominant reverse faulting on E-to-NE trending structures, resolving long-standing ambiguities in its causative mechanism. The 1978 Ferruzzano earthquake, previously characterized by conflicting interpretations, was redefined as a Mw 4.7 event with a NS normal faulting mechanism. Our findings underscore the invaluable role of analog seismograms in extending the seismic record, refining earthquake parameters, and constraining seismotectonic models. In addition, these results demonstrate the feasibility of applying modern techniques to historical data, paving the way for future investigations focused on early instrumental seismicity. By addressing challenges related to data preservation, digitization, and analysis, our work contributes to the ongoing efforts to compile comprehensive datasets for historical earthquakes. These datasets are essential for improving seismic hazard assessment and informing risk mitigation strategies, ultimately supporting the resilience of vulnerable communities to earthquake-related natural hazards.
How to cite: Presti, D., Totaro, C., Scolaro, S., Batlló, J., Orecchio, B., and Stich, D.: Moment Tensor Inversion from Historical Seismograms: Case Studies in Southern Italy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20013, https://doi.org/10.5194/egusphere-egu25-20013, 2025.
After the earthquakes in Zagreb and Petrinja in 2020, numerous churches, cultural and historical buildings built before 1964. throughout Northern Croatia suffered damage. Most of the damage includes damage to roofs, chimneys and unreinforced walls. Most of the injured of sacred buildings as well as cultural and older buildings in Northern Croatia was created on the prominent topographic localities - elevations.
The research was carried out in several stages:
- study of the macroseismic intensity map of the 2020 earthquake to detect potential topographic locations in search of damage that consequence of topographical effects
- study of the report on the inspection of statically damaged churches caused by earthquakes in the area of Varaždinska diocese
- review and synthesis of available literature on the earthquake damage consequences and protection measures of the Zagreb and Petrinja earthquakes on the cultural assets of Varaždin, Međimurje and Zagorje counties
- field investigations of individual topographic locations - gathering as much information as possible about the buildings, historical constructions and renovations and topographic characteristics. Preliminary measurements of microtremor were made for the purpose of detection predominant frequencies of the topographic locality.
The goal of historical data research was to gain insight into recurring damage from historical earthquakes on the topographic locality itself or in the immediate vicinity in order to try to learn about the influence of topography on this basis damage from the earthquakes themselves.
How to cite: Kovač, S., Stanko, D., Dogančić, D., and Pascuttini Juraga, V.: Review of historical data on earthquake damage to sacral buildings in northwestern Croatia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21239, https://doi.org/10.5194/egusphere-egu25-21239, 2025.
