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

Giovanni Martinelli^1*Fuqiong Huang²Caibo Hu³Yongsheng Zhou⁴Fabrizio Gherardi⁵

• ¹National Institute of Geophysics and Volcanology, Section of Palermo, Palermo, Italy
• ²China Earthquake Networks Center, Beijing, China
• ³University of the Chinese Academy of Sciences, Beijing, China
• ⁴China Earthquake Administration Institute of Geology, Beijing, China
• ⁵Istituto di Geoscienze e Georisorse Consiglio Nazionale delle Ricerche, Pisa, Italy

Goals and contents of this research topic "Faults and Earthquakes Viewed by Networks, Monitoring Systems and by Numerical Modelling Techniques" refer to recent research on earthquake processes which uses multidisciplinary approaches from geophysical, geochemical, geodetical, and geological parameters. Enhancing risk appraisal and prediction abilities is the most relevant disaster mitigation approach in seismically active locations. Multidisciplinary investigations of small-scale cracks in the lab and seismogenic features in field test locations have helped us comprehend earthquake processes from preparation to faulting in recent decades. Preearthquake observations, methods, and perspectives can enhance our understanding of the processes preceding earthquakes. Modeling, which can be used to set up earthquake forecasting experiments, verifies test site areas, large or small, worldwide. There are 13 articles collected for this Research Topic, involving geochemical and hydrogeological parameters in tectonically active areas (4 articles), ground deformations (2 articles), stress modeling (2 articles), source modeling (1 article), apparent resistivity of rocks (1 article), microsisms location (1 article), teleseismic location (1 article), ground motion measurements (1 article)2.1) High potential precursors of earthquakes from Geochemical and hydrogeological parameters A review paper by Li et al. (2024), examines the geochemical characteristics of fault zone gases and their implications for understanding fault activity and seismic events. The study underscores the importance of isotope tracing in deciphering fluid sources, migration pathways, and the evolution of fault zones. The original paper by et al (2024) assessed the sensitivity and validity of various geochemical parameters as monitoring and precursory parameters in Beijing, a key seismic monitoring area. Zhang et al. (2025) examined eight wells situated near the Longmenshan-Anninghe fault zone, which exhibit significant disparities in changes of groundwater level. The Authors quantified the observed changes using the Molchan diagram and investigated potential factors that may affect it using correlation analyses. Yang et al (2025) described five soil gas continuous stations to carry out observations of fault gas concentrations within the Yanqing Fault zone. The results show that the time series of the hydrogen (H2) gas concentration has a close relationship with local seismic activity and far-field strong earthquakes. Chen et al (2025) introduce a novel fault coseismic dislocation inversion method based on parallel elastic finite element simulations. The authors conducted inversion tests using various idealized fault models to validate their approach. With combining geodetic and seismological analysis, Lin et al (2024) found that afterslip is the dominant mechanism of near-to intermediate-field postseismic deformation and also likely represents the driving force that controls aftershock productivity and the spatiotemporal migration of seismicity The proposed model by Xu and Zeng (2024) reveals the relationships between differential stress, seismicity, brittle-ductile transition, and boundary depth of the upper and lower crust in the continental crust, and connects the multiple observations from geophysics and geology in southeastern Tibetan plateau. The obtained results of Lei et al (2024) suggest that the high Load/Unload response ratio value before its decline may mark the end of the rock medium's yielding phase, and Outgoing Longwave Radiation data can reflect, to some extent, the state of tectonic stress accumulating along active faults in a critical condition.2.4 Favoured model for source modeling de Lorenzo and Michele, using a proposed new technique, applied it to a small-magnitude earthquake (ML3.3) that occurred in central Italy, identified the most likely rupture models, and examined the issue of correlation among model parameters.For the investigated event, a circular crack model was resulted favored over a heterogeneous rupture model. Lei et al. (2024) provide a reference for earthquake precursor studies on how to quantitatively remove environmental interference in anisotropy and how to avoid areas with large local influences. The article by Wu et al (2024) proposes a high-precision location algorithm for 3D-Fast Sweeping Method seismic sources to develop a small-scale regional microseismic location model for coal mines. The paper by Yuan et al (2024) proposes a fully automatic approach by integrating the advantages of seismic scanning based on navigated automatic phase-picking, which can automatically detect and locate seismic events from continuous waveforms, and the depth-scanning algorithm, and determine the precuise focal depth of local and regional earthquakes by matching depth phases. The method can be used to establish high-quality teleseismic catalogues and depth-phase databases. Zhou et al ( 2025) deployed a seismic array in Gongquan town to observe seismic activities and analyzed the amplification effects in the area. The research results from weak-motion seismograms of aftershocks indicate significant seismic ground motion amplification in Gongquan town. The observed phenomenon reminds us to pay special attention to the risk of significant damage caused by the combined effects of extreme amplification in future earthquake defense efforts. The advancement of geosciences is grounded in modern observational methodologies. Utilizing extensive laboratory experimental methods, several scientists have shown that earthquakes may be preceded by potential precursors that might facilitate forecasting. The prolonged accumulation of previous events has provided insights into the mechanisms behind the preparation of significant earthquakes. This volume contains several unique concepts that can enhance the knowledge of earthquake mechanisms. This Research Topic emphasizes the complex nature of seismic activity and has favored submissions that employ geophysical, geochemical, and geodetic techniques to elucidate the earthquake process from nucleation to manifestation. The scope includes innovative research utilizing observation networks and sophisticated numerical modeling that synthesizes diverse data. A critical re-assessment of the suggested methodologies, along with cutting-edge and innovative insights, may clarify favored avenues for research. The primary objective is to present an updated overview of existing information about the processes that precede earthquake occurrence. This information may be utilized to establish earthquake forecasting experiments designed to assess their accuracy across various geophysical settings. GM: writing-original draft, writing-review and editing, conceptualization, and investigation. FH:writing-original draft and writing-review and editing. CH:writing-original draft and writing-review and editing-review and editing. YZ: writing-original draft and writing-review and editing. FG:writing-original draft and writing-review and editing.