The 2021-2022 Hunga Tonga-Hunga Ha'apai eruption in Tonga was among the largest of recent decades. The event was notable for its high intensity, generating a convective column that rapidly ascended well into the stratosphere; for the atmospheric pressure wave generated by the explosion, which was detected globally; and for generating a tsunami that was observable across Pacific Ocean shorelines. Following a series of preceding seismic and explosive events since December 2021, the sustained phase of the eruption on 15th January was relatively short lived, but the associated pressure wave and tsunami impacts were the most far-reaching since the eruption of Krakatau volcano in 1883. Tsunamis were recorded both locally and in the far-field, but their mechanism(s) remains uncertain; in the near field being from either (or both of) the collapsing eruption column or a phreatomagmatic explosion as the erupting mass mixed with sea water. In the far-field the tsunamis are possibly best explained by the massive atmospheric pressure wave, that is the first instrumentally recorded eruption-generated event of its type, which affected the entire global atmosphere and ionosphere, causing the observed infrasound waves and unusual long-period seismic resonances.
This interdisciplinary late-breaking session welcomes contributions from all disciplines involved in local and global observations of this eruption and its effects, including remote sensing observations and modeling as well as hazard assessment and estimation of damage and long-term consequences.

Heat extremes are already one of the deadliest meteorological events and they are projected to increase in intensity and frequency due to rising CO2 emissions. The hazard these events pose to society may therefore increase dramatically, and society will need to adapt if the worst impacts are to be avoided. This session therefore welcomes a broad range of new research addressing the challenge of extreme heat. Suitable contributions may: (i) assess the drivers and underlying processes of extreme heat in observations and/or models; (ii) explore the diverse socio-economic impacts of extreme heat events (for example, on aspects relating to human health or economic productivity); (iii) address forecasting of extreme heat at seasonal to sub-seasonal time scales; (iv) focus on societal adaptation to extreme heat, including the implementation of Heat-Health Early Warning Systems for disaster risk reduction.

Worldwide, the frequency and magnitude of extreme floods are steadily increasing, causing large scale flooding, accompanied by great economic/human losses, in inundation-prone areas of the world. It hampers well-being and economic growth in many countries, so that flood forecasting and flood risk assessment & management have become of upmost importance. New and rapidly developing techniques are becoming widespread, such as UAV (unmanned aerial vehicle), ML(Machine Learning) or satellite-based systems (e.g., SAR, Altimeter, SCATSAT-1, etc.). Combined with fit-for-purpose hydrodynamic/hydrological models, these techniques pave the way for breakthroughs in flood assessment and flood risk management. This provides a unique platform for the scientific community to explore the driving mechanisms of flood risk and to build up efficient strategies for flood mitigation and enhancing flood resilience. Emerging advances in computing technologies, coupled with big-data mining, have boosted data-driven applications, among which ML technology bearing flexibility and scalability in pattern extraction has modernised not only scientific thinking but also predictive applications.
This session invites presentations on research based on high-resolution aerial, satellite and ML techniques for flood monitoring and modelling, including mapping of inundation extent, flow depths, velocity fields, flood-induced morphodynamics, and debris transport. It also invites the presentation of innovative modelling techniques of flood hydrodynamics, flood hazard, damage and risk assessment, as well as flood relief prioritization, dam and dike (levees) break floods, and flood mitigation strategies. Studies dealing with the modelling uncertainties and modern techniques for model calibration and validation are particularly welcome. Furthermore, real-time flood inundation mapping is a critical aspect for the evacuation of people from low-lying areas and to reduce casualties. Acquisition of real-time data gained through UAV-based flood inundation mapping, ML and modelling techniques, as well as assessment of uncertainties in real-time aerial surveying are welcome in this session.

With global climate change affecting the frequency and severity of extreme meteorological and hydrological events, it is particularly necessary to develop models and methodologies for a better understanding and forecasting of present-day weather induced hazards. Future changes in the event characteristics as well as changes in vulnerability and exposure are among the further factors for determining risks for infrastructure and society, and for the development of suitable adaptation measures. This session considers extreme events that lead to disastrous hazards induced by severe weather and climate change. These can, e.g., be tropical or extratropical rain- and wind-storms, hail, tornadoes or lightning events, but also (toxic) floods, long-lasting periods of drought, periods of extremely high or of extremely low temperatures, etc. Papers are sought which contribute to the understanding of their occurrence (conditions and meteorological development), to assessment of their risk (economic losses, infrastructural damages, human fatalities, pollution), and their future changes, to the ability of models to reproduce them and methods to forecast them or produce early warnings, to proactive planning focusing on damage prevention and damage reduction. In order to understand fundamental processes, papers are also encouraged that look at complex extreme events produced by combinations or sequences of factors that are not extreme by themselves. The session serves as a forum for the interdisciplinary exchange of research approaches and results, involving meteorology, hydrology, environmental effects, hazard management and applications like insurance issues.

Lightning is the energetic manifestation of electrical breakdown in the atmosphere, occurring as a result of charge separation processes operating on micro and macro-scales, leading to strong electric fields within thunderstorms. Lightning is associated with tropical storms and severe weather, torrential rains and flash floods. It has significant effects on various atmospheric layers and drives the fair-weather electric field. It is a strong indicator of convective processes on regional and global scales, potentially associated with climate change. Thunderstorms and lightning are also associated with the production of energetic radiation up to tens of MeV on time scales from sub-millisecond (Terrestrial Gamma-ray Flashes) to tens of seconds (gamma-ray glows).

This session seeks contributions from research in atmospheric electricity with emphasis on:

Atmospheric electricity in fair weather and the global electrical circuit
Effects of dust and volcanic ash on atmospheric electricity
Thunderstorm dynamics and microphysics
Middle atmospheric Transient Luminous Events
Energetic radiation from thunderstorms and lightning
Experimental investigations of lightning discharge physics processes
Remote sensing of lightning and related phenomena by space-based sensors
Thunderstorms, flash floods, tropical storms and severe weather
Modeling of thunderstorms and lightning
Now-casting and forecasting of thunderstorms using machine learning and AI
Regional and global lightning detection networks
Lightning Safety and its Societal Effects

Climate-induced geohazards are known to increase with climate change causing more intense rainfall and more frequent extreme weather events. Use of vegetation on potentially unstable slopes and along stream banks is an example of Nature-Based Solutions (NBS) that can mitigate climate induced geohazards due their role at the soil-atmosphere interface. Vegetating slopes or stream banks are also key for ecological restoration and rewilding, providing several additional co-benefits. However, researchers in different fields of science or practitioners do not easily communicate, even though they are addressing aspects of the same problem.
Interdisciplinary research and bilateral communication are needed to document the effects of vegetation in hazard-prone areas in a measurable and applicable manner. These NBS must have an ecological approach, where in the long-term perspective, a multiple approach for biodiversity and ecosystem services will give mutual synergies.

This session aims to stimulate interdisciplinary communication, knowledge exchange and dissemination on plant-soil-atmosphere interaction, with focus on vegetation mitigating climate-induced geohazards, particularly shallow landslides and erosion.
Contributions documenting how vegetation and roots can be beneficial also in land use planning, restoration ecology, climate change adaptation are welcome within the fields of geotechnical engineering, plant ecology, biodiversity, alpine timberline, hydrogeology and agronomy.
Interaction between research and industry, with involvement of NBS entrepreneurs, are particularly welcome.

Topics of interested are listed, including, but not limited to:
• Experimental, either laboratory or field, or numerical investigation of plant-soil-atmosphere interaction and its relation to slope or bank stability
• How to implement morpho-mechanical parameters of plants in engineering design?
• Measuring and quantifying the effects of vegetation as NBS to mitigate climate-induced geohazards
• Tools, approaches, and frameworks demonstrating how vegetation can be used to mitigate climate-induced geohazards, while providing additional co-benefits
• Investigation on upscaling potential from laboratory to slope and catchment scale
• Case studies of restoration or stabilisation works, especially on design principles and performance assessment
• Ensuring interdisciplinary interaction and mutual synergies for studies containing vegetation as NBS among different disciplines

In many parts of the world, weather represents one of the major uncertainties affecting performance and management of agricultural systems. Due to global climate changes the climatic variability and the occurrence of extreme weather events is likely to increase leading to substantial increase in agricultural risk and destabilisation of farm incomes. This issue is not only important for farm managers but also for policy makers, since income stabilisation in agriculture is frequently considered as a governmental task.

The aim of this session is to discuss the state of the art research in the area of analysis and management of weather-related risks in agriculture. Both structural and non-structural measures can be used to reduce the impact of climate variability including extreme weather on crop production. While the structural measures include strategies such as irrigation, water harvesting, windbreaks etc., the non-structural measures include the use of the medium-range weather forecast and crop insurance.

The topic is at the borderline of different disciplines, in particular agricultural and financial economics, meteorology, modelling and agronomy. Thus, the session offers a platform to exchange ideas and views on weather-related risks across these disciplines with the focus on quantifying the impact of extreme weather on agricultural production including impacts of climate change, analysis of financial instruments that allow reducing or sharing weather-related risks, evaluation of risk management strategies on the farm level, development of the theory of risk management and to exchange practical experiences with the different types of weather insurance.

This session has been promoted by:
• Natural hazard Early career scientists Team (NhET, https://blogs.egu.eu/divisions/nh/tag/early-career-scientists/)
• Research Center for the Management of Agriculutral and Environmental Risks (CEIGRAM, http://www.ceigram.upm.es/ingles/)

Flash floods triggered by heavy precipitation in small- to medium-sized catchments often cause catastrophic damages, which are largely explained by the very short response times and high specific peak discharge. Often, they are also associated with geomorphic processes such as erosion, sediment transport, debris flows and shallow landslides. The anticipation of such events is crucial for efficient crisis management. However, their predictability is still affected by large uncertainties, due to the fast evolution of triggering rainfall events, the lack of appropriate observations, the high variability and non-linearity in the physical processes, the high variability of societal exposure, and the complexity of societal vulnerability.
This session aims to illustrate current advances in monitoring, modeling, and short-range forecasting of flash floods and associated geomorphic processes, including their societal impacts.
Contributions related to the floods that occured in July 2021 in Germany and Western Europe, and in October 2020 in France and Italy (Alex storm) are particularly encouraged this year.
Contributions on the following scientific themes are specifically expected:
- Monitoring and nowcasting of heavy precipitation events based on radar and remote sensing (satellite, lightning, etc.) to complement rain gauge networks;
- Short-range (0-6h) heavy precipitation forecasting based on NWP models, with a focus on seamless forecasting strategies and ensemble strategies for the representation of uncertainties;
- Understanding and modeling of flash floods and associated geomorphic processes at appropriate space-time scales;
- Development of integrated hydro-meteorological forecasting chains and new modeling approaches for predicting flash floods and/or rainfall-induced geomorphic hazards in gauged and ungauged basins;
- New direct and indirect (proxy data) observation techniques and strategies for the observation or monitoring of hydrological reactions and geomorphic processes, and the validation of forecasting approaches;
- Development of impact-based modeling and forecasting approaches, including inundation mapping and/or specific impacts modeling approaches for the representation of societal vulnerability.

Urban hydrological processes are characterized by high spatial variability and short response times resulting from a high degree of imperviousness. Therefore, urban catchments are especially sensitive to space-time variability of precipitation at small scales. High-resolution precipitation measurements in cities are crucial to properly describe and analyses urban hydrological responses. At the same time, urban landscapes pose specific challenges to obtaining representative precipitation and hydrological observations.

This session focuses on high-resolution precipitation and hydrological measurements in cities and on approaches to improve modeling of urban hydrological response, including:
- Novel techniques for high-resolution precipitation measurement in cities and for multi-sensor data merging to improve the representation of urban precipitation fields.
- Novel approaches to hydrological field measurements in cities, including data obtained from citizen observatories.
- Precipitation modeling for urban applications, including convective permitting models and stochastic rainfall generators.
- Novel approaches to modeling urban catchment properties and hydrological response, from physics-based, conceptual and data-driven models to stochastic and statistical conceptualization.
- Applications of measured precipitation fields to urban hydrological models to improve hydrological prediction at different time horizons to ultimately enable improved management of urban drainage systems (including catchment strategy development, flood forecasting and management, real-time control, and proactive protection strategies aimed at preventing flooding and pollution).
- Strategies to deal with upcoming challenges, including climate change and rapid urbanization.

Extreme hydro-meteorological events drive many hydrologic and geomorphic hazards, such as floods, landslides and debris flows, which pose a significant threat to modern societies on a global scale. The continuous increase of population and urban settlements in hazard-prone areas in combination with evidence of changes in extreme weather events lead to a continuous increase in the risk associated with weather-induced hazards. To improve resilience and to design more effective mitigation strategies, we need to better understand the aspects of vulnerability, risk, and triggers that are associated with these hazards.
This session aims at gathering contributions dealing with various hydro-meteorological hazards that address the aspects of vulnerability analysis, risk estimation, impact assessment, mitigation policies and communication strategies. Specifically, we aim to collect contributions from academia, the industry (e.g. insurance) and government agencies (e.g. civil protection) that will help identify the latest developments and ways forward for increasing the resilience of communities at local, regional and national scales, and proposals for improving the interaction between different entities and sciences.
Contributions focusing on, but not limited to, novel developments and findings on the following topics are particularly encouraged:
- Physical and social vulnerability analysis and impact assessment of hydro-meteorological hazards
- Advances in the estimation of socioeconomic risk from hydro-meteorological hazards
- Characteristics of weather and precipitation patterns leading to high-impact events
- Relationship between weather and precipitation patterns and socio-economic impacts
- Hazard mitigation procedures
- Strategies for increasing public awareness, preparedness, and self-protective response
- Impact-based forecast, warning systems, and rapid damage assessment.
- Insurance and reinsurance applications

The assessment of precipitation variability and uncertainty is crucial in a variety of applications, such as flood risk forecasting, water resource assessments, evaluation of the hydrological impacts of climate change, determination of design floods, and hydrological modelling in general. This session aims to gather contributions on research, advanced applications, and future needs in the understanding and modelling of precipitation variability, and its sources of uncertainty.
Contributions focusing on one or more of the following issues are particularly welcome:
- Novel studies aimed at the assessment and representation of different sources of uncertainty versus natural variability of precipitation.
- Methods to account for accuracy in precipitation time series due to, e.g., change and improvement of observation networks.
- Uncertainty and variability in spatially and temporally heterogeneous multi-source precipitation products.
- Estimation of precipitation variability and uncertainty at ungauged sites.
- Precipitation data assimilation.
- Process conceptualization and approaches to modelling of precipitation at different spatial and temporal scales, including model parameter identification and calibration, and sensitivity analyses to parameterization and scales of process representation.
- Modelling approaches based on ensemble simulations and methods for synthetic representation of precipitation variability and uncertainty.
- Scaling and scale invariance properties of precipitation fields in space and/or in time.
- Physically and statistically based approaches to downscale information from meteorological and climate models to spatial and temporal scales useful for hydrological modelling and applications.

Hydro-meteorological extremes such as floods, droughts, storms, or heatwaves often affect large regions therefore causing large damages and costs. Hazard and risk assessments, aiming at reducing the negative consequences of such extreme events, are often performed with a focus on one location despite the spatially compounding nature of extreme events. While spatial extremes receive a lot of attention by the media, little is known about their driving factors and it remains challenging to assess their risk by modelling approaches. Key challenges in advancing our understanding of spatial extremes and in developing new modeling approaches include the definition of multivariate events, the quantification of spatial dependence, the dealing with large dimensions, the introduction of flexible dependence structures, the estimation of their probability of occurrence, the identification of potential drivers for spatial dependence, and linking different spatial scales. This session invites contributions which help to better understand processes governing spatial extremes and/or propose new ways of describing and modeling spatially compounding events at different spatial scales.

This session brings together scientists, forecasters, practitioners and stakeholders interested in exploring the use of ensemble hydro-meteorological forecast techniques in hydrological applications: e.g., flood control and warning, reservoir operation for hydropower and water supply, transportation, and agricultural management. It will address the understanding of sources of predictability and quantification and reduction of predictive uncertainty of hydrological extremes in deterministic and ensemble hydrological forecasting. Uncertainty estimation in operational forecasting systems is becoming a more common practice. However, a significant research challenge and central interest of this session is to understand the sources of predictability and development of approaches, methods and techniques to enhance predictability (e.g. accuracy, reliability etc.) and quantify and reduce predictive uncertainty in general. Ensemble data assimilation, NWP preprocessing, multi-model approaches or hydrological postprocessing can provide important ways of improving the quality (e.g. accuracy, reliability) and increasing the value (e.g. impact, usability) of deterministic and ensemble hydrological forecasts. The models involved with the methods for predictive uncertainty, data assimilation, post-processing and decision-making may include machine learning models, ANNs, catchment models, runoff routing models, groundwater models, coupled meteorological-hydrological models as well as combinations (multimodel) of these. Demonstrations of the sources of predictability and subsequent quantification and reduction in predictive uncertainty at different scales through improved representation of model process (physics, parameterization, numerical solution, data support and calibration) and error, forcing and initial state are of special interest to the session.

Drought and water scarcity are important issues in many regions of the Earth. While the projected increase in the severity and frequency of droughts can lead to water scarcity situations, particularly in regions that are already water-stressed, overexploitation of available water resources can exacerbate the consequences of droughts. In the worst case, this can lead to long-term environmental and socio-economic impacts. Drought Monitoring and Forecasting are recognized as one of three pillars of effective drought management, and it is, therefore, necessary to improve both monitoring and sub-seasonal to seasonal forecasting for droughts and water availability and to develop innovative indicators and methodologies that translate the information provided into effective drought early warning and risk management. This session addresses statistical, remote sensing and physically-based techniques, aimed at monitoring, modelling and forecasting hydro-meteorological variables relevant to drought and/or water scarcity. These include, but are not limited to, precipitation, snow cover, soil moisture, streamflow, groundwater levels, and extreme temperatures. The development and implementation of drought indicators meaningful to decision-making processes, and ways of presenting and integrating these with the needs and knowledge of water managers, policymakers and other stakeholders, are further issues that are addressed. The session aims to bring together scientists, practitioners and stakeholders in the fields of hydrology and meteorology, as well as in the field of water resources and/or drought risk management, also including drought and water scarcity interrelationship, hydrological impacts, and feedbacks with society. Particularly welcome are applications and real-world case studies in regions subject to significant water stress, where the importance of drought warning, supported through state-of-the-art monitoring and forecasting of water resources availability, is likely to become more important in the future.

With recent extreme events reaching far beyond existing records, such as the Pacific Northwest heat wave and severe flooding in Western Europe, eastern US and across China, the discussion to what extent we are prepared for unprecedented extremes and whether existing methods and models are able to capture them has flared up. It is becoming increasingly essential to understand and quantify plausible rare, high-impact events for risk management and adaptation.
Methods to understand and evaluate low-likelihood extreme events have seen substantial advancements over the recent years. Event attribution studies are now providing rapid analyses of unprecedented extreme events; physical climate storylines are developed to evaluate plausible rather than likely events; causal inference is used to understand drivers of very rare events; near-miss events and potential analogues in space, historical and paleo archives are evaluated; spatial extreme value analysis and machine learning methods are applied, large ensembles representing various outcomes are generated, such as Single Model Initial-condition Large Ensembles (SMILEs); and weather prediction systems are increasingly being employed, such as the through the UNprecedented Simulated Extremes using ENsembles (UNSEEN) approach.
This session aims to bring together communities from weather prediction, climate projection, hydrology to impact and risk management, and to learn from the variety of methods to understand and quantify low-likelihood extreme events in the present and future climate. The session welcomes contributions at all temporal and spatial scales, and all types of extremes and invites novel methods – including downward counterfactuals and causal inference – as well as new results on unforeseen climate risks – including those from compound events and low-likelihood high-warming outcomes.

This interactive session aims to bridge the gap between science and practice in operational forecasting for different climate and water-related natural hazards including their dynamics and interdependencies. Operational (early) warning systems are the result of progress and innovations in the science of forecasting. New opportunities have risen in physically based modelling, coupling meteorological and hydrological forecasts, ensemble forecasting, impact-based forecasting and real time control. Often, the sharing of knowledge and experience about developments are limited to the particular field (e.g. flood forecasting or landslide warnings) for which the operational system is used. Increasingly, humanitarian, disaster risk management and climate adaptation practitioners are using forecasts and warning information to enable anticipatory/ early action that saves lives and livelihoods. It is important to understand their needs, their decision-making process and facilitate their involvement in forecasting and warning design and implementation (co-development).

The focus of this session will be on bringing the expertise from different fields together as well as exploring differences, similarities, problems and solutions between forecasting systems for varying hazards including climate emergency. Real-world case studies of system implementations - configured at local, regional, national, continental and global scales - will be presented, including trans-boundary issues. An operational warning system can include, for example, monitoring of data, analysing data, making and visualizing forecasts, giving warning signals and suggesting early action and response measures.

Contributions are welcome from both scientists and practitioners who are involved in developing and using operational forecasting and/or management systems for climate and water-related hazards, such as flood, drought, tsunami, landslide, hurricane, hydropower, pollution etc. We also welcome contributions from early career practitioners and scientists.

Urban areas are at risk from multiple hazards, including urban flooding, droughts and water shortages, sea level rise, disease spread and issues with food security. Consequently, many urban areas are adapting their approach to hazard management and are applying Green Infrastructure (GI) solutions as part of wider integrated schemes.

This session aims to provide researchers with a platform to present and discuss the application, knowledge gaps and future research directions of urban GI and how sustainable green solutions can contribute towards an integrated and sustainable urban hazard management approach. We welcome original research contributions across a series of disciplines with a hydrological, climatic, soil sciences, ecological and geomorphological focus, and encourage the submission of abstracts which demonstrate the use of GI at a wide range of scales and geographical distributions. We invite contributions focusing on (but not restricted to):

· Monitored case studies of GI, Sustainable Drainage Systems (SuDS) or Nature Based Solutions (NBS), which provide an evidence base for integration within a wider hazard management system;

· GIS and hazard mapping analyses to determine benefits, shortcomings and best management practices of urban GI implementation;

· Laboratory-, field- or GIS-based studies which examine the effectiveness or cost/benefit ratio of GI solutions in relation to their wider ecosystem potential;

· Methods for enhancing, optimising and maximising GI system potential;

· Innovative and integrated approaches or systems for issues including (but not limited to): bioretention/stormwater management; pollution control; carbon capture and storage; slope stability; urban heat exchange, and; urban food supply;

· Catchment-based approaches or city-scale studies demonstrating the opportunities of GI at multiple spatial scales;

· Rethinking urban design and sustainable and resilient recovery following crisis onset;

· Engagement and science communication of GI systems to enhance community resilience.

Forecasting the weather, in particular severe and extreme weather has always been the most important subject in meteorology. This session will focus on recent research and developments on forecasting techniques, in particular those designed for operations and impact oriented. Contributions related to nowcasting, meso-scale and convection permitting modelling, ensemble prediction techniques, and statistical post-processing are very welcome.
Topics may include:
 Nowcasting methods and systems, use of observations and weather analysis
 Mesoscale and convection permitting modelling
 Ensemble prediction techniques
 Ensemble-based products for severe/extreme weather forecasting
 Seamless deterministic and probabilistic forecast prediction
 Post-processing techniques, statistical methods in prediction
 Use of machine learning, data mining and other advanced analytical techniques
 Impact oriented weather forecasting
 Presentation of results from relevant international research projects of EU, WMO, and EUMETNET etc.

This session investigates mid-latitude cyclones and storms on both hemispheres. We invite studies considering cyclones in different stages of their life cycles from the initial development, to large- and synoptic-scale conditions influencing their growth to a severe storm, up to their dissipation and related socioeconomic impacts.
Papers are welcome, which focus also on the diagnostic of observed past and recent trends, as well as on future storm development under changed climate conditions. This will include storm predictability studies on different scales. Finally, the session will also invite studies investigating impacts related to storms: Papers are welcome dealing with vulnerability, diagnostics of sensitive social and infrastructural categories and affected areas of risk for property damages. Which risk transfer mechanisms are currently used, depending on insured and economic losses? Which mechanisms (e.g. new reinsurance products) are already implemented or will be developed in order to adapt to future loss expectations?

It becomes increasingly accepted that many regions all over the world are experiencing an increase in the frequency of extreme rainfall events and potentially in their properties. For predicting the impact of future climate change on the landscape, it is therefore vital to understand the dynamics of surface processes under extreme events. Furthermore, focusing on the conditions necessary for extreme events to occur can provide key insights into past changes in climate at different time scales. Extreme storms cause a multitude of hydrogeomorphic and natural hazards responses, including floods and respective fluvial responses, hillslope erosion and failures, and debris flows from slopes into fluvial systems. Measuring, evaluating, and predicting the impacts of extreme rainstorms, however, remains challenging due to the difficult-to-predict and complex nature of storms and rainfall-surface interactions.
This interdisciplinary session focuses on the causative chain which links the deterministic and mostly stochastic nature of the synoptic to meso/regional and watershed scales of extreme storms, to their respective transformation into watershed, slope, and stream hydrology, and to their geomorphic impact. We welcome studies from all the parts of this chain, from all climates, and at all temporal scales, that are focusing on the hydrological responses to extreme events and on their imprints on the landscape through erosion and sediment movement. We favor studies with emphasis on the final noticeable impact of extreme events on the landscape and/or on the integrated long-term consequences of extreme storm regime on landscape evolution. Especially, we encourage studies presenting new physical/stochastic modeling approaches that explicitly investigated the impact of extreme events on the landscape.

Low-lying coastal areas can be an early casualty to sea-level rise, especially where enhanced by land subsidence. An ever increasing number of studies indicates that land subsidence due to natural and anthropogenic causes has induced damage to wetland ecosystems in many countries worldwide, and has increased flooding hazard and risk. Coastal subsidence causes include excessive groundwater extraction from aquifers, peat oxidation due to surface water drainage through land reclamation, urbanization and agricultural use, as well as sediment starvation due to construction of dams and artificial levees. Contrary to the global processes behind sea-level rise, natural and anthropogenic coastal subsidence is primarily a local phenomenon, and its causes and severity may vary substantially from place to place.
The combination of geological and historical measurements with remote sensing data is required to understand all drivers of coastal vertical land motion and the contributions to past, present, and future subsidence.
Understanding coastal subsidence requires multidisciplinary expertise, models, and remote and in-situ observations from geology, geodesy, natural hazards, oceanography, hydrogeology, and geomechanics. In this session, we aim to bring together all the involved disciplines. We invite contributions on all aspects of coastal subsidence research and applications, including recent advances on: i) measurement through ground-based, aerial and satellite remote sensing techniques, ii) numerical models and future projections, iii) their applicability to distinguish between the different drivers contributing to land subsidence, and iv) quantification of coastal hazards associated with relative sea-level rise. In particular, efforts towards characterizing human intervention on coastal vertical land motion are welcomed.

Transport of sediments in geophysical flows occurs in mountainous, fluvial, estuarine, coastal, aeolian and other natural or man-made environments on Earth, while also shapes the surface of planets such as Mars, Titan, and Venus. Understanding the motion of sediments is still one of the most fundamental problems in hydrological and geophysical sciences. Such processes can vary across a wide range of scales - from the particle to the landscape - which can directly impact both the form (geomorphology) and, on Earth, the function (ecology and biology) of natural systems and the built infrastructure surrounding them. In particular, feedback between flow and sediment transport as well as interparticle interactions including size sorting are a key processes in surface dynamics, finding a range of important applications, from hydraulic engineering and natural hazard mitigation to landscape evolution and river ecology.

Specific topics of interest include (but are not restricted to):

A) particle-scale interactions and transport processes:
-mechanics of entrainment and disentrainment (for fluvial and aeolian flows)
-momentum (turbulent impulses) and energy transfer between turbulent flows and particles
-upscaling and averaging techniques for stochastic transport processes
-interaction among grain sizes in poorly sorted mixtures, including particle segregation

B) reach-scale sediment transport and geomorphic processes
-bedform generation, evolution and disintegration dynamics (e.g. for dunes and other formations)
-discrete element modelling of transport processes and upscaling into continuum frameworks
-derivation and solution of equations for multiphase flows (including fluvial and aeolian flows)
-shallow water hydro-sediment-morphodynamic processes

C) large-scale, highly unsteady and complex water-sediment flows:
-flash floods, debris flows and landslides due to extreme rainfall
-natural and build dam failures and compound disasters (due to landslides, debris flow intrusion and downstream flooding)
-reservoir operation schemes and corresponding fluvial processes
-design of hydraulic structures such as fish passages, dam spillways, also considering the impact of sediment
-dredging, maintenance and regulation for large rivers and navigational waterways

Sediment transport is a fundamental component of all geomorphic systems (including fluvial, aeolian, coastal, hillslopes and glacial), yet it is something that we still find surprisingly difficult both to monitor and to model. Robust data on where and how sediment transport occurs are needed to address outstanding research questions, including the spatial and temporal controls on critical shear stress, the influence of varying grain size distributions, and the impact of large magnitude events. Recent developments have provided a) new opportunities for measuring sediment transport in the field; and b) new ways to represent sediment transport in both physical laboratory models and in numerical models. These developments include (but are not limited to) the application of techniques such as seismic and acoustic monitoring, 3D imaging (e.g. CT and MRI scanning), deployment of sensors such as accelerometers, replication of field topography using 3D printing, use of luminescence as a sediment tracer, remote sensing of turbidity, discrete numerical modelling, and new statistical approaches.

In this session we welcome contributions from all areas of geomorphology that develop new methods for monitoring and modelling all types of sediment transport, or that showcase an application of such methods. Contributions from ECRs and underrepresented groups are particularly encouraged.

Volcanoes play an essential role in society through their impacts on human
life, infrastructure, and the environment. Those in marine settings pose
hazards, such as the awakening of submarine volcanoes, underwater
explosions, and sudden release of harmful gases from the volcano or
overlying water column, and tsunami inundation of neighboring coastlines
due to caldera collapse, submarine landslides, or entry of pyroclastic
flows into the sea. Specifically, volcanic degassing plays a dominant role
in forcing the timing and nature of volcanic unrest and eruptions in such
settings. On the other hand, quiescent passive degassing and
smaller-magnitude eruptions can impact the regional climate system. For
those reasons understanding the exsolution processes of gas species
dissolved in magma and measuring their emissions is crucial to
characterize the eruptive mechanism and evaluate the subsequent impacts on
the atmospheric composition, the environment, and the biosphere.
The session will be focused on multidisciplinary monitoring volcanic
environments, including in the vicinity of cities and highly touristic areas. Since
gas emissions are measured and monitored via in-situ and remote sensing
techniques, we invite contributions to studies that gain insights into the
subterranean-surface processes and quantify their impacts. In addition, we
encourage studies that focus on modelling the subsurface and
atmospheric/climatic processes and laboratory experiments that are
fundamental to the interpretation of field-based and satellite
observations. Finally, we will undoubtedly discuss the ability to
recognize the hazards and their impact on people, emergency management by
civil protection authorities, community education, case studies and risk
mitigation to reduce the effects of volcanism and its societal impact.

The session deals with the documentation and modelling of the tectonic, deformation and geodetic features of any type of volcanic area, on Earth and in the Solar System. The focus is on advancing our understanding on any type of deformation of active and non-active volcanoes, on the associated behaviours, and the implications for hazards. We welcome contributions based on results from fieldwork, remote-sensing studies, geodetic and geophysical measurements, analytical, analogue and numerical simulations, and laboratory studies of volcanic rocks.

Studies may be focused at the regional scale, investigating the tectonic setting responsible for and controlling volcanic activity, both along divergent and convergent plate boundaries, as well in intraplate settings. At a more local scale, all types of surface deformation in volcanic areas are of interest, such as elastic inflation and deflation, or anelastic processes, including caldera and flank collapses. Deeper, sub-volcanic deformation studies, concerning the emplacement of intrusions, as sills, dikes and laccoliths, are most welcome.

We also particularly welcome geophysical data aimed at understanding magmatic processes during volcano unrest. These include geodetic studies obtained mainly through GPS and InSAR, as well as at their modelling to imagine sources.



The session includes, but is not restricted to, the following topics:

volcanism and regional tectonics;
formation of magma chambers, laccoliths, and other intrusions;
dyke and sill propagation, emplacement, and arrest;
earthquakes and eruptions;
caldera collapse, resurgence, and unrest;
flank collapse;
volcano deformation monitoring;
volcano deformation and hazard mitigation;
volcano unrest;
mechanical properties of rocks in volcanic areas.

Developing physical-mathematical models able to describe the evolution of eruptive phenomena is a key point in volcanology. In the case of high-risk phenomena, such as lava flows or ash dispersal, predicting their spatial and temporal evolution and determining the potentially affected areas is fundamental in supporting every action directed at mitigating the risk as well as for environmental planning.
This session aims to address unresolved challenging questions related to complex geophysical flow modeling and simulation, gathering physical-mathematical models, numerical methods and field and satellite data analysis in order to: (i) expand knowledge of complex volcanic processes and their space-time dynamics; (ii) monitor and model volcanic phenomena; (iii) evaluate model robustness through validation against real case studies, analytical solutions and laboratory experiments; (iv) quantify the uncertainty propagation through both forward (sensitivity analyses) and inverse (optimization/calibration) modelling in all components of volcanic hazard modelling in response to eruptive crises.

Glaciers and volcanoes interact in a number of ways, including instances where volcanic/geothermal activity alters glacier dynamics or mass balance, via subglacial eruptions or the deposition of supraglacial tephra. Glaciers can also impact volcanism, for example by directly influencing mechanisms of individual eruptions resulting in the construction of distinct edifices. Glaciers may also influence patterns of eruptive activity when mass balance changes adjust the load on volcanic systems, the water resources and hydrothermal systems. However, because of the remoteness of many glacio-volcanic environments, these interactions remain poorly understood.
In these complex settings, hazards associated with glacier-volcano interaction can vary from lava flows to volcanic ash, lahars, landslides, pyroclastic flows or glacial outburst floods. These can happen consecutively or simultaneously and affect not only the earth, but also glaciers, rivers and the atmosphere. As accumulating, melting, ripping or drifting glaciers generate signals as well as degassing, inflating/ deflating or erupting volcanoes, the challenge is to study, understand and ultimately discriminate these potentially coexisting signals. We wish to fully include geophysical observations of current and recent events with geological observations and interpretations of deposits of past events. Glaciovolcanoes also often preserve a unique record of the glacial or non-glacial eruptive environment that is capable of significantly advancing our knowledge of how Earth's climate system evolves.
We invite contributions that deal with the mitigation of the hazards associated with ice-covered volcanoes in the Arctic, Antarctic or globally, that improve the understanding of signals generated by ice-covered volcanoes, or studies focused on volcanic impacts on glaciers and vice versa. Research on recent activity is especially welcomed. This includes geological observations e.g. of deposits in the field or remote-sensing data, together with experimental and modelling approaches. We also invite contributions from any part of the world on past activity, glaciovolcanic deposits and studies that address climate and environmental change through glaciovolcanic studies. We aim to bring together scientists from volcanology, glaciology, seismology, geodesy, hydrology, geomorphology and atmospheric science in order to enable a broad discussion and interaction.

The Fagradalsfjall eruption on the Reykjanes Peninsula of Iceland started on 19 March 2021. It provides a unique opportunity to study all aspects of a low-intensity effusive basaltic eruption in great detail using multidisciplinary approaches. The Fagradalsfjall eruption followed a several-week long period of intense seismicity and deformation associated with formation of the feeding dike. The eruption terminated on September 18, 2021, after producing a lava field covering about 4.5 km2. The eruption progressed through several phases, each characterized by different emission sources, eruptive style, intensities, and associated hazards. The eruption may be representative of the formation of a shield volcano, a process that the scientific community has had limited chances to observe in real time.

We welcome submissions on sustained low-intensity basaltic eruptions including (but not limited to) the 2021 Fagradalsfjall eruption; their plumbling systems, eruptive products, and impacts. We particularly encourage comparative studies across different regions that may help us to better understand the volcanic processes that are active in the Fagradalsfjall eruption.

Topics may include, for example: physical volcanology of eruptive products and eruptive behavior; lava flow modeling; acoustic studies; petrology; geochemistry and interaction with groundwater; studies of volcanic gases; crustal deformation; seismology; volcano monitoring; social effects; health effects; hazard mitigation; tectonic implications; volcano-tectonic interactions; atmosphere-climate interactions, etc.

Over the past few years, major technological advances significantly increased both the spatial coverage and frequency bandwidth of multi-disciplinary observations at active volcanoes. Networks of instruments, both ground- and satellite-based, now allow for the quantitative measurement of geophysical responses, geological features and geochemical emissions, permitting an unprecedented, multi-parameter vision of the surface manifestations of mass transport beneath volcanoes. Furthermore, new models and processing techniques have led to innovative paradigms for inverting observational data to image the structures and interpret the dynamics of volcanoes. In particular, machine learning, a type of AI in which computers learn from data, is gaining importance in volcanology, not only for monitoring purposes (i.e., in real-time) but also for later hazards analysis (e.g. modelling tools).

Within this context, this session aims to bring together a multidisciplinary audience to discuss the most recent innovations in volcano imaging and monitoring, and to present observations, methods and models that increase our understanding of volcanic processes.
We welcome contributions (1) related to methodological and instrumental advances in geophysical, geological and geochemical imaging of volcanoes, (2) to explore new knowledge provided by these studies on the internal structure and physical processes of volcanic systems, and (3) to investigate the potential of machine learning techniques to process multispectral satellite data for developing a better understanding of volcanic hazards.

We invite contributors from all geophysical, geological and geochemical disciplines: seismology, electromagnetics, geoelectrics, gravimetry, magnetics, muon tomography, volatile measurements and analysis. The session will include in-situ monitoring and high- resolution remote sensing studies that resolve volcanic systems ranging from near-surface hydrothermal activity to deep magma migration.

Volcanic islands are simultaneously some of the tallest and fastest-forming geological features on Earth and constitute the site of significant geohazards ranging from volcanic eruptions, earthquakes, landslides, and tsunamis. Ocean island volcanoes are also some of the most enigmatic features in our planet, as their genesis is still not satisfactorily explained by conventional plate tectonics. The scientific community faces several challenges in studying volcanic islands, particularly in what regards processes taking place at depth. There is still a need to densify seismic networks in volcanic islands, using both land- and seafloor-based stations, to record the signals associated with volcanic and tectonic processes and automatically or manually detect and classify those signals. 3D images from the shallow crust to the deep mantle are crucial to unravel the geodynamic processes behind the generation of volcanism. More accurate quantification of temporal changes in the volcanic systems will help in the forecasting of potential eruptions and the monitoring of existing ones. On top of that, the presence of geothermal systems and induced seismicity from industrial exploration are also critical challenges in volcanic islands due to the system's complexity.
Considering the enormous diversity of interactions in volcanic islands, we welcome contributions from a wide range of studies including: seismo-volcanic monitoring and tracking of magma movements; characterization and location of volcanic tremor; 3D and 4D seismic imaging, including attenuation tomography; seismic ambient noise monitoring; machine learning to detect and classify volcanic earthquakes; active source studies to characterize volcanic flanks and landslides; induced and triggered seismicity in geothermal systems; and seismic sources.

This session is devoted to the most recent eruption of the Cumbre Vieja volcano, which started on Sept. 19, 2021, on the island of La Palma after 50 years of repose. Volcanic unrest was recorded in Oct. 2017, when a seismic swarm was located at more than 20 km depths. Nine additional swarms followed, the last one was recorded in June 2021. Geochemical anomalies followed this increased seismicity indicating a magmatic recharge at depth. On Sept. 11, 2021, a new seismic swarm was observed at shallower depths (10-12 km), indicating a possible magmatic intrusion. This was confirmed when geodetic monitoring networks on the island started showing clear signs of inflation. The seismicity increased in frequency and intensity with many felt earthquakes. Seismic activity accelerated in the morning of Sept. 19 when a strong shallow earthquake was widely felt on the western part of the island. This was the precursor of the eruption, which started at about 14:10 UTC on the same day. A series of vents opened along a fissure close to Los Llanos on the western flank of Cumbre Vieja volcano. The eruption displayed vigorous lava fountaining and powerful Strombolian explosions while lava effusion produced a compound Aa flow field. The eruption has destroyed hundreds of buildings, plantations as well as cutting vital transport routes.
This session is open to contributions aimed at geological, geophysical, geochemical and volcanological studies of the eruption and its precursors and, more in general, to studies that can help better understanding the eruptive dynamics. We also welcome contributions focused on the management of scientific communication during this crisis and the management of the volcanic emergency.

Volcanoes are inherently complex and dynamic geological system, acting as the source of diverse sediment types and as a control on varied sediment transport processes within surrounding environments, both during and after their life. This can manifest as an accumulation of thick primary volcaniclastic sequences from pyroclastic (e.g. pyroclastic density currents, tephra falls), laharic and flank instability processes, secondary volcaniclastic sequences from the reworking/redeposition (or both) of primary deposits and their interaction with non-volcanic sedimentary processes, or deposits from the weathering of lava flows. The diversity of processes that may be involved in the generation of volcaniclastic sequences makes often difficult to describe and interpret them. As the comprehension of the generation, transportation and accumulation mechanisms of volcaniclastic sequences is of extreme importance for natural hazard and economic perspectives, to reduce uncertainties and move forward in the identification of volcano-sedimentary processes and potential effects, modern and ancient volcaniclastic sequences must be studied and interpreted hand in hand. Thus, the proposed session aims to bring together studies that explore the volcaniclastic record of modern and ancient environments. Contributions are welcomed in areas including, but not limited to, the identification of volcanic features in ancient sedimentary records, multidisciplinary (e.g., stratigraphic, petrographic, geophysical) approaches to the study of modern subaerial and submarine volcaniclastic sequences as analogue sites, and examples of the modification of sedimentary systems across syn- and inter-eruptive periods.

Debris flows are among the most dangerous natural hazards that threaten people and infrastructures in both mountainous and volcanic areas. The study of the initiation and dynamics of debris flows, along with the characterization of the associated erosion/deposition processes, is of paramount importance for hazard assessment, land-use planning and design of mitigation measures, including early warning systems. In addition, the impacts of climate change on debris-flow activity must be considered and carefully analysed, as the number of mountain areas prone to these events may increase in future.
A growing number of scientists with diverse backgrounds are studying debris flows and lahars. The difficulties in measuring parameters related to their initiation and propagation have progressively prompted research into a wide variety of laboratory experiments and monitoring studies. However, there is a need of improving the quality of instrumental observations that would provide knowledge for more accurate hazards maps and modeling. Nowadays, the combination of distributed sensor networks and remote sensing techniques represents a unique opportunity to gather direct observations of debris flows to better constrain their physical properties.
Scientists working in the field of debris flows are invited to present their recent advancements. In addition, contributions from practitioners and decision makers are also welcome. Topics of the session include: field studies and documentation, mechanics of debris-flow initiation and propagation, laboratory experiments, modeling, monitoring, impacts of climate change on debris-flow activity, hazard and risk assessment and mapping, early warning, and alarm systems.