Faults and Earthquakes Viewed by Networks, Monitoring Systems and by Numerical Modelling Techniques

Rock rheology governs the deformation of rocks in reaction to forces within the Earth's interior. Rheology is the scientific study of material properties, specifically focusing on the relationship between stress (force per unit area) and strain rate (rate of deformation). With the emergence of plate tectonics, it has become clear that comprehending the movement of plates alone is not enough to properly explain the interaction between Earth's lithosphere and mantle convection, as well as other driving forces. This is apparent when analyzing the intricate deformation patterns of plate boundary zones, which can now be accurately traced using space geodetic methods. The rheology of rocks is influenced by various factors, such as mineralogy, geofluid composition and content, grain size of minerals, amount of melt present, temperature, pressure, and the circumstances of differential stress. The variation in mineralogical and chemical composition of rocks is vast, and our understanding of crucial factors such regional heat movement and tectonic pressures is expanding over time. The convective pattern in the upper mantle under the tectonic plates is not directly linked to the plate boundaries. Instead, it could be identified and studied by analyzing geophysical parameters like topography, gravity, S-wave dispersion, heat flux etc.

Nevertheless, earthquakes are now the sole means of directly observing motions occurring below the Earth's surface at depths exceeding a few kilometers. The correlation between the depths at which these earthquakes occur and the speeds at which subduction takes place indicates that the occurrence of seismic activity is influenced by various parameters like temperature. In this Research Topic we seek to comprehend the factors that differentiate the seismic movement of certain faults from the creeping movement of others. What are the first causes of faults and how do they progress into plate boundaries? The mapping of geofluids has allowed for the identification of areas that have experienced significant tectonic activity. Essentially, places with active tectonic activity and geofluids will continue to experience earthquakes until major global geodynamic events change the current state of tectonic activity.

This Research Topic attempts to present the most advanced studies on the mechanisms of earthquakes, using geophysical, geochemical, geodetic, and statistical methods. The focus is on understanding the entire process, from the initial nucleation to the occurrence of the earthquake. Recent meetings held by the Asia Oceania Geosciences Society, the European Geosciences Union, the American Geophysical Union etc. underlined the crucial importance of observatory networks of monitoring systems from space, ground and subsurface based on multiple kind of sensors, of potential anomalies related to the inter-seismic (pre-seismic), co-post-seismic processes and their spatial and temporal scales of advances in numerical modelling of the physical processes of nucleation, dynamic rupturing, and seismic wave propagating of earthquakes based on coupling of multiple disciplinary observation data and of possible further researches related to the occurrence of great earthquakes and of induced seismicity.

Keywords: brittle-ductile transition, deformation mechanisms, shear zone, crustal permeability, earthquake related phenomena, earthquake precursors, seismic hazard, heat flux, S-waves dispersion, viscosity, gas geochemistry, water geochemistry, poroelasticity, volcanoes

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