Abstract
Physical laws governing friction on shallow faults in the Earth and spatial heterogeneity of parameters are critical to our understanding of earthquake physics and the assessment of earthquake hazards. Here we use a laboratory-derived fault-friction law and high-quality strong-motion seismic recordings of the 2020 Elazığ earthquake, Turkey, to reveal the complex rupture dynamics. We discover an initial Mw 5.8 rupture stage and explain how cascading behavior of the event, involving at least three episodes, each of M > 6, caused it to evolve into a large earthquake, contrarily to other M5+ events on this part of the East Anatolian Fault. Although the dynamic stress transfer during the rupture did not overcome the strength of the uppermost ~5 kilometers, surface ruptures during future earthquakes cannot be ruled out. We foresee that future, routine dynamic inversions will improve understanding of earthquake rupture parameters, an essential component of modern, physics-based earthquake hazard assessment.
Highlights
Physical laws governing friction on shallow faults in the Earth and spatial heterogeneity of parameters are critical to our understanding of earthquake physics and the assessment of earthquake hazards
Our Bayesian dynamic source inversion revealed information imprinted in the near-fault strong motion seismograms, suggesting the following picture of the Elazığ earthquake and its broader role in the fault evolution
The event occurred on the Pütürge segment of the East Anatolian Fault Zone (EAFZ), situated between strong earthquakes that happened 100–150 years ago, and, since that time, the segment remained with no Mw 6+ occurrence
Summary
Physical laws governing friction on shallow faults in the Earth and spatial heterogeneity of parameters are critical to our understanding of earthquake physics and the assessment of earthquake hazards. We foresee that future, routine dynamic inversions will improve understanding of earthquake rupture parameters, an essential component of modern, physics-based earthquake hazard assessment. The feasibility of dynamic rupture inversions was demonstrated in the 1990’s5,8,9, there are just a handful of realdata discoveries in coseismic dynamics, with none yet from the East Anatolian Fault Zone (EAFZ). Recent studies employing InSAR, GPS and creepmeter data report creep within a zone from surface to the seismogenic depth, along the segments to the north-east of Lake Hazar[21,22,23]. Based on seismic data of the Turkish networks, and using innovative methodology, we decipher stress and frictional parameters of the Elazığ earthquake fault rupture in a detail allowing new tectonic and mechanical interpretations. We explain why the recent earthquake did not produce surface faulting, and we show that moderate earthquakes of the interseismic period are undeveloped rudiments of potentially large events
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