Geophysical methods have a great potential for characterizing subsurface properties and couple THM processes to inform geological, reservoir, hydrological, and (bio)geochemical studies. In these contexts, the classically used geophysical tools only provide indirect information about subsurface heterogeneities, reservoir rocks characteristics, thermo-hydro-mechanical coupling, and associated processes (e.g. flow, transport, bio-geochemical reactions). Rock physics relationships hence have to be developed to provide links between physical properties (e.g. electrical conductivity, seismic velocity or attenuation) and the intrinsic parameters of interest (e.g. fluid content, hydraulic properties, coupled processes). In addition, geophysical methods are increasingly deployed as time-lapse, or even continuous, and distributed monitoring tools on more and more complex environments. Here again, there is a great need for accurate and efficient physical relationships such that geophysical data can be correctly interpreted (e.g. included in fully coupled inversions). Establishing such models requires multidisciplinary approaches since involved theoretical frameworks differ. Each physical property has its intrinsic dependence to pore-scale interfacial, geometrical, and (bio)geochemical properties or to external condition (such as pressure or temperature). Each associated geophysical method has its specific investigation depth and spatial resolution which adds a significant level of complexity in combining and scaling theoretical developments with laboratory studies/validations and/or with field experiments. This session consequently invites contributions from various communities to share their models, their experiments, or their field tests and data in order to discuss about multidisciplinary ways to improve our knowledge on reservoir and near surface environment.

Rock deformation at different stress levels in the brittle regime and across the brittle-ductile transition is controlled by damage processes occurring on different spatial scales, from grain scale to fractured rock masse. These lead to a progressive increase of micro- and meso-crack intensity in the rock matrix and to the growth of inherited macro-fractures at rock mass scale. Coalescence of these fractures forms large-scale structures such as brittle fault zones and deep-seated rock slide shear zones. Diffuse or localized rock damage have a primary influence on rock properties (strength, elastic moduli, hydraulic and electric properties) and their evolution across multiple temporal scales spanning from geological times to highly dynamic phenomena as earthquakes, volcanic eruptions and landslides. In subcritical stress conditions, damage accumulation results in brittle creep processes key to the long-term evolution of geophysical, geomorphological and geo-engineering systems.

Damage and progressive failure processes must be considered to understand the time-dependent hydro-mechanical behaviour of faults (e.g. stick-slip vs asesismic creep), volcanic systems and slopes (e.g. slow rock slope deformation vs catastrophic rock slides), as well as the response of rock masses to stress perturbations induced by artificial excavations (tunnels, mines) and static or dynamic loadings. At the same time, damage processes control the brittle behaviour of the upper crust and are strongly influenced by intrinsic rock properties (strength, fabric, porosity, anisotropy), geological structures and their inherited damage, as well as by the evolving pressure-temperature with increasing depth and by fluid pressure, transport properties and chemistry. However, many complex relationships between these factors and rock damage are yet to be understood.

In this session we will bring together researchers from different communities interested in a better understanding of rock damage processes and consequence. We welcome innovative contributions on experimental studies (both in the laboratory and in situ), continuum / micromechanical analytical and numerical modelling, and applications to fault zones, reservoirs, slope instability and landscape evolution, and engineering applications. Studies adopting novel approaches and combined methodologies are particularly welcome.

Invited speakers:
- Brian Collins  (U.S. Geological Survey)
-  Jérôme Aubry  (Ecole Normale Supérieure de Paris)

Since 2004, there have been a number of large subduction earthquakes whose unexpected rupture features contributed to the generation of devastating tsunamis. The impact that these events have had on human society highlights the need to improve our knowledge of the key mechanisms behind their origin. Advances in these areas have led to progress in our understanding of the most important parameters affecting tsunamigenesis.

With increasing geophysical data, new descriptions of faulting and rupture complexity are being hypothesized (e.g., spatial and temporal seismic rupture heterogeneity, fault roughness, geometry and sediment type, interseismic coupling, etc.). Rock physicists have proposed new constitutive laws and parameters based on a new generation of laboratory experiments, which simulate close to natural seismic deformation conditions on natural fault samples. In addition, advances in numerical modelling now allow scientists to test how new geophysical observations, e.g. ocean drilling projects and laboratory analyses, influence subduction zone processes over a range of temporal and spatial scales (i.e., geodynamic, seismic cycling, earthquake rupture, wave propagation modelling).

In light of these advances, this session has a twofold mission: i) to integrate recent results from different fields to foster a comprehensive understanding of the key parameters controlling the physics of large subduction earthquakes over a range of spatial and temporal scales; ii) to identify how tsunami hazard analysis can benefit from using a multi-disciplinary approach.

We invite abstracts that enhance interdisciplinary collaboration and integrate observations, rock physics experiments, analog- and numerical modeling, and tsunami hazard.

This session covers the broad field of earthquake source processes, and
includes the topics of imaging the rupture kinematics and simulating
earthquake dynamics using numerical methods, to develop a deeper
understanding of earthquake source physics. We also invite presentation
that link novel laboratory experiments to earthquake dynamics, and
studies on earthquake scaling properties.

Earthquake sources are imaged using seismic data and surface deformation
measurements (e.g.GPS and InSAR) to estimate rupture properties on
faults and fault systems. Each data set and each method has its strength
and limitations in the context of the source-inversion problem, but the
uncertainties are often not well quantified and the robustness of the
source models not well known.
The session invites contributions that address the source-inversion
problem and provide new methods, innovative applications, and
thought-provoking new ideas. Contributions are welcome that make use of modern
computing paradigms and infrastructure to tackle large-scale forward
simulation of earthquake process, but also inverse modeling to retrieve
the rupture process with proper uncertainty quantification.

Earthquake source imaging, numerical modeling of rupture dynamics, and
source-scaling relations help to understand earthquake source processes.
Furthermore, new numerical modeling approaches for multi-scale
earthquake physics, including earthquake-cycle simulations, may include
fault-zone evolution and even target seismic hazard assessment. The
question that these lines of research are targeting are profound and of
first-order socio-economic relevance:

Which first-order physical processes control, at a given space-time
scale, the macroscopic evolution of dynamic rupture and its seismic
radiation? Is the physics of fault rupture the same for large and small
earthquakes? How can modern earthquake hazard assessment profit from a
deeper understanding of rupture dynamics? Which source processes need to
be considered to better understand, and then model, tsunami generation,
triggering phenomena, induced seismicity and earthquake cycles?

Within this framework our session also provides a forum to discuss case
studies of kinematic or dynamic source modeling of recent significant
earthquakes.

Numerous cases of induced/triggered seismicity have been reported in the last decades, directly or indirectly related to anthropogenic activity for the geo-resources exploration. Induced earthquakes felt by local population can often negatively affect public perception of geo-energies and may lead to the cancellation of important projects. Furthermore, large earthquakes may jeopardize wellbore stability and damage surface infrastructure. Thus, monitoring and modeling processes leading to fault reactivation, (seismic or aseismic) are critical to develop effective and reliable forecasting methodologies during deep underground exploitation. The complex interaction between injected fluids, subsurface geology, stress interactions, and resulting induced seismicity requires an interdisciplinary approach that accounts for coupled thermo-hydro-mechanical-chemical processes to understand the triggering mechanisms.
In this session, we invite contributions from research aimed at investigating the interaction of the above processes during exploitation of underground resources, including hydrocarbon extraction, wastewater disposal, geothermal-energy exploitation, hydraulic fracturing, gas storage and production, mining, and reservoir impoundment for hydro-energy. We particularly encourage novel contributions based on laboratory and underground near-fault experiments, numerical modeling, the spatio-temporal relationship between seismic properties, injection/extraction parameters, and/or geology, and fieldwork. Contributions covering both theoretical and experimental aspects of induced and triggered seismicity at multiple spatial and temporal scales are welcome.

The deformation energy budget describes how energy is stored and consumed within crustal systems. Energy stored as uplift against gravity, off-fault deformation and/or mineralogic changes can be released in the creation of new fractures, frictional heating along faults and/or radiated seismic energy. Innovative field measurements, numerical modeling and experimental approaches are providing new constraints on the energy budget within deforming crustal systems. The energy budget framework allows comparison of the energetic importance of diverse deformational processes operating in crustal systems. This framework enables tracking the evolution of the energy budget throughout time, and comparing energy budget partitioning in any tectonic system as individual fault segments propagate, interact and perhaps link. Moreover, the energy budget framework governs the rupture style and slip distribution during an individual earthquake, and is key in understanding multi-fault ruptures. Evidence suggests that new faults develop in order to optimize the overall efficiency of the system. Thus, constraining which processes dominate the budget in various tectonic systems and moments in time may help predict the timing and geometry of fault and rupture propagation and interaction. For this session, we encourage contributions that provide estimates of the evolving components of the energy budget using diverse methods, including numerical models, scaled physical analog experiments, deformation experiments on natural rock, and geophysical and field observations. Interdisciplinary work that combines several of these techniques are particularly encouraged.

Earthquake mechanics is controlled by a spectrum of processes covering a wide range of length scales, from tens of kilometres down to few nanometres. While the geometry of the fault/fracture network and its physical properties control the global stress distribution and the propagation/arrest of the seismic rupture, earthquake nucleation and fault weakening is governed by frictional processes occurring within extremely localized sub-planar slipping zones. The co-seismic rheology of the slipping zones themselves depends on deformation mechanisms and dissipative processes active at the scale of the grain or asperity. The study of such complex multiscale systems requires an interdisciplinary approach spanning from structural geology to seismology, geophysics, petrology, rupture modelling and experimental rock deformation. In this session we aim to convene contributions dealing with different aspects of earthquake mechanics at various depths and scales such as:

· the thermo-hydro-mechanical processes associated with co-seismic fault weakening based on rock deformation experiments, numerical simulations and microstructural studies of fault rocks;
· the study of natural and experimental fault rocks to investigate the nucleation mechanisms of intermediate and deep earthquakes in comparison to their shallow counterparts;
· the elastic, frictional and transport properties of fault rocks from the field (geophysical and hydrogeological data) to the laboratory scale (petrophysical and rock deformation studies);
· the internal architecture of seismogenic fault zones from field structural survey and geophysical investigations;
· the modeling of earthquake ruptures, off-fault dynamic stress fields and long-term mechanical evolution of realistic fault networks;
· the earthquake source energy budget and partitioning between fracture, friction and elastic wave radiation from seismological, theoretical and field observations.
· the interplay between fault geometry and earthquake rupture characteristics from seismological, geodetic, remote sensed or field observations;

We particularly welcome novel observations or innovative approaches to the study of earthquake faulting. Contributions from early career scientists are solicited.

Geological and geophysical data sets are in essence the output of physical processes governing the Earth’s evolution. Such data sets are widely varied and range from the internal structure of the Earth (e.g. seismic tomography), plate kinematics (e.g. GPS), composition of geomaterials (e.g. petrography), estimation of physical conditions and dating of key geological events (e.g. thermobarometry), thermal state of the Earth (e.g heat-flow measurements) to more shallow processes such as natural and “engineered” reservoir dynamics and waste sequestration in the subsurface (e.g. seismic imaging).

Combining the abundant data to process-based numerical models fosters our understanding of the dynamical Earth. Process-based models are powerful tools to predict the evolution of complex natural systems resolving the feedbacks among various physical processes. Integrating high-quality data into direct numerical simulations leads to a constructive workflow to further constrain the key parameters within the models. Innovative inversion strategies, linking forward dynamic models with observables, are topics triggering a growing interest within the community.

The complexity of geological systems arises from their multi-physics nature, as they combine hydrological, thermal, chemical and mechanical. Multi-physics couplings are prone to nonlinear interactions ultimately leading to spontaneous localisation of flow and deformation. Understanding the couplings among those processes requires the development of appropriate tools to capture spontaneous localisation and represents a challenging though essential research direction.

We invite contributions from the following two complementary themes:

#1 Computational advances associated with
- alternative spatial and/or temporal discretisation for existing forward/inverse models
- scalable HPC implementations of new and existing methodologies (GPUs / multi-core)
- solver and preconditioner developments
- AI / Machine learning-based approaches
- code and methodology comparisons (“benchmarks”)
- open source implementations for the community

#2 Physics advances associated with
- development of partial differential equations to describe geological processes
- inversion strategies and adjoint-based modelling
- numerical model validation through comparison with observables (data)
- scientific discovery enabled by 2D and 3D modelling
- utilisation of coupled models to explore nonlinear interactions

With an increasing demand for low-carbon energy solutions, the need of geothermal resources utilization is accelerating. Geothermal energy can be extracted from various, often complex geological settings, e.g. fractured crystalline rock, magmatic systems or sedimentary basins. Current advancements also target unconventional systems (e.g., Enhanced Geothermal Systems, super-hot, pressurized and co-produced, super-critical systems) besides conventional hydrothermal systems. Optimizing investments leads to the development of associated resources such as lithium, rare earths and hydrogen. This requires a joint effort for monitoring, understanding and modelling geological systems that are specific to each resource.
A sustainable use of geothermal resources requires advanced understanding of the properties of the entire system during exploration as well as monitoring, including geophysical properties, thermo-/petro-physical conditions, fluid composition; structural and hydrological features; and engineering challenges. Challenges faced are, among others, exploration of blind systems, reservoir stimulation, induced seismicity or related to multiphase fluid and scaling processes.

The integration of analogue field studies with real-life production data, from industrial as well as research sites, and their organization and the combination with numerical models, are a hot topic worldwide. With this session we aim to gather field, laboratory and numerical experts who focus their research on geothermal sites, to stimulate discussion in this multi-disciplinary applied research field. We seek for contributions from all disciplines, ranging from field data acquirements and analysis to laboratory experiments, e.g. geophysical surveys or geochemical experiments, and from the management and organization of information to numerical models as well as from (hydro)geologists, geochemists, (geo)physicists, surface and subsurface engineers.

Fractures are discontinuities in rocks that are present in almost all geological settings and at any scale. They may represent small-scale fissures or build up large scale faults. Fractures are extreme forms of heterogeneities, often with a small extension but huge impact.
The presence of fractures modifies the bulk physical properties of the original media by many orders of magnitudes, and they often introduce a strongly nonlinear behavior. This refers in particular to the mechanical properties via reduction of strength and stiffness. Fractures also provide the main flow and transport pathways in hard rock aquifers, dominating over the permeability of the rock matrix, as well as creating anisotropic flow fields and transport. Understanding their hydraulic and mechanical properties of fractures and fracture networks thus are crucial for predicting the movement of any fluid such as of water, air, hydrocarbons, or CO2. Consequently, fractures are of great importance in various disciplines such as hydrogeology, hydrocarbon reservoir management, and geothermal reservoir engineering.
The geologist toolbox to explore and model fractured rocks is getting more and more extended. This session is dedicated to novel ideas and concepts on treating the challenges related to the generic understanding, the characterization and the modelling of fractured geological media.
Contributions are welcome from the following topics
• Exploration methods for mechanical and/or hydraulic characterization of fractured media
• Structural construction of fractured media by deterministic or stochastic approaches,
• Representation of static hydraulic and/or mechanical characteristics of fractured media involving continuous or discontinuous methods,
• Simulation of dynamic processes and the hydraulic and/or mechanical behavior of fractured media,
• Theoretical studies and field applications in fractured geological formations,
• Concepts of accounting for fractured properties specifically in groundwater, petroleum or geothermal management applications.

Many regions of the Earth, from crust to core, exhibit anisotropic fabrics which can reveal much about geodynamic processes in the subsurface. These fabrics can exist at a variety of scales, from crystallographic orientations to regional structure alignments. In the past few decades, a tremendous body of multidisciplinary research has been dedicated to characterizing anisotropy in the solid Earth and understanding its geodynamical implications. This has included work in fields such as: (1) geophysics, to make in situ observations and construct models of anisotropic properties at a range of depths; (2) mineral physics, to explain the cause of some of these observations; and (3) numerical modelling, to relate the inferred fabrics to regional stress and flow regimes and, thus, geodynamic processes in the Earth. The study of anisotropy in the Solid Earth encompasses topics so diverse that it often appears fragmented according to regions of interest, e.g., the upper or lower crust, oceanic lithosphere, continental lithosphere, cratons, subduction zones, D'', or the inner core. The aim of this session is to bring together scientists working on different aspects of anisotropy to provide a comprehensive overview of the field. We encourage contributions from all disciplines of the earth sciences (including mineral physics, seismology, magnetotellurics, geodynamic modelling) focused on anisotropy at all scales and depths within the Earth.

The goal of this session is to reconcile short-time/small-scale and long-time/large-scale observations, including geodynamic processes such as subduction, collision, rifting or mantle lithosphere interactions. Despite the remarkable advances in experimental rock mechanics, the implications of rock-mechanics data for large temporal and spatial scale tectonic processes are still not straightforward, since the latter are strongly controlled by local lithological stratification of the lithosphere, its thermal structure, fluid content, tectonic heritage, metamorphic reactions and deformation rates.

Mineral reactions have mechanical effects that may result in the development of pressure variations and thus are critical for interpreting microstructural and mineral composition observations. Such effects may fundamentally influence element transport properties and rheological behavior.
Here, we encourage presentations focused on the interplay between metamorphic processes and deformation on all scales, on the rheological behavior of crustal and mantle rocks and time scales of metamorphic reactions in order to discuss
(1) how and when up to GPa-level differential stress and pressure variations can be built and maintained at geological timescales and modelling of such systems,
(2) deviations from lithostatic pressure during metamorphism: fact or fiction?,
(3) the impact of deviations from lithostatic pressure on geodynamic reconstructions.
(4) the effect of porous fluid and partial melting on the long-term strength.
We therefore invite the researchers from different domains (rock mechanics, petrographic observations, geodynamic and thermo-mechanical modelling) to share their views on the way forward for improving our knowledge of the long-term rheology and chemo-thermo-mechanical behavior of the lithosphere and mantle.

This session concerns about the interrelation between microstructures and geologic processes. One the one hand, microstructures (fabrics, textures, grain sizes, shapes, etc) can be used to identify or quantify, e.g., deformation, metamorphic, magmatic or diagenetic phenomena (to name a few). On the other hand, physical properties of geo-materials are governed by their microstructure, hence predicting a materials property is greatly enhanced by understanding of how certain processes result in a specific microstructure.

All these mechanisms are likely to cause modification on the rheological, elastic, and thermal properties of these rocks, providing key information on the evolution of the lithosphere.
In this session, we invite contributions from field observations, laboratory experiments, and numerical modelling that relate microstructures to rheology, strain localization or mineral reactions, that use microstructures to tackle general problems in structural, metamorphic, magmatic or economic geology as well as studies quantifying physical and mechanical properties of rocks based on their microstructural and textural properties using well established or novel methods.

Dynamic processes shape the Earth and other planets throughout their history. Geochemical observations place major constraints on dynamical processes that operated throughout Earth’s history while seismic imaging gives a snapshot of today’s mantle. Knowledge of physical properties and rheology from mineral physics is key to quantify processes in the mantle, and is undergoing constant advances (e.g. related to the iron spin transition or the thermal conductivity of the core). Magma ocean crystallisation established the initial conditions for subsequent long-term Earth evolution but is not well understood and typically not considered in models of long-term evolution. Modern-day plate tectonics may not have operated in the past; there is active debate about what tectonic mode(s) may have preceded it and their geological and geochemical signatures.

This session aims to provide a multidisciplinary view of the dynamics and evolution of the Earth, including its mantle, lithosphere, core and atmosphere. We welcome contributions that address aspects of this problem including geochemical observations and their interpretation, new mineral physics findings, geodynamical modelling, and seismological observations, on temporal scales ranging from the present day to billions of years, and on spatial scales ranging from microscopic mineralogical samples to global models. Contributions that take a multidisciplinary approach are particularly welcome.

Invited speaker: Matthew Jackson, Saskia Goes, Lorenzo Colli, Paula Koelemeijer