Abstract
Earthquakes are the result of strain build-up from without and erosion from within faults. A generic co-seismic condition includes merely three angles representing respectively fault geometry, fault strength and the ratio of fault coupling to lithostatic load. Correspondingly, gravity fluctuation, bridging effect, and granular material production/distribution form the earthquake triad. As a dynamic component of the gravity field, groundwater fluctuation is the nexus among the three intervened components and plays a pivotal role in regulating major earthquake irregularity: reducing natural (dry) inter-seismic periods and lowering magnitudes. It may act mechanical-directly (MD) through super-imposing a seismogenic lateral stress field thus aiding plate-coupling from without; or mechanical-indirectly (MI) by enhancing fault fatigue, hence weakening the fault from within. A minimum requirement for a working earthquake prediction system is stipulated and implemented into a well-vetted numerical model. This fatigue mechanism based modeling system is an important supplement to the canonical frictional theory of tectonic earthquakes. For collisional systems (e.g., peri-Tibetan Plateau regions), MD mechanism dominates, because the orographically-induced spatially highly biased precipitation is effectively channeled into deeper depth by the prevalence of through-cut faults. Droughts elsewhere also are seismogenic but likely through MI effects. For example, ENSO, as the dominant player for regional precipitation, has strong influence on the gravity field over Andes. Major earthquakes, although bearing the same 4 - 7 years occurrence frequency as ENSO, have a significant hiatus, tracing gravity fluctuations. That granular channels left behind by seamounts foster major earthquakes further aver the relevance of MI over Andes. Similarly, the stability of the Cascadia fault is found remotely affected by Californian droughts (2011-15), which created a 0.15 kPa/km stress gradient along the Pacific range, which also is the wave guide.
Highlights
Tectonic earthquakes are frictional phenomena between contacting plates (Scholz, 1998; Wang & Hu, 2006; Wang & He, 1999)
The mechanisms we identified after sedulous essays using the singular SEGMENT model and remote sensing data are whetted against 73 historical cases, all within the reanalyses period with quality precipitation data
Earthquake occurs when the plate-coupling stress determined repose angle reaches the sum of two angles representing respectively fault geometry and fault strength
Summary
Tectonic earthquakes are frictional phenomena between contacting plates (Scholz, 1998; Wang & Hu, 2006; Wang & He, 1999). Θ is the slope of the fault zone, determined by the geometry of the plate interface, and θ f is the maximum static friction angle corresponding to fault strength. With fault strength set as constant, fault geometry and plate-coupling stress determine a natural (limiting) earthquake occurrence frequency. In addition to the parameterizations of material rheology (visco-elastic mantle, granular debris as produced by seismic events of all kinds, and the brittle elastic crust), Section 3 is dedicated to the setting of the fault-following model grids, static geologic properties (e.g., plate interface geometry and physical property of each layer of medium)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
