9/3/2023 0 Comments A strike slip fault![]() ![]() 6, 2023, resulted in significant loss of life and widespread damage. ![]() For example, the Turkey–Syria earthquake doublet that occurred on Feb. Understanding the dynamics of multi-fault ruptures is important, said Gabriel, because these types of earthquakes are typically more powerful than those that occur on a single fault. “High-performance computing has allowed us to understand the driving factors of these large events, which can help inform seismic hazard assessment and preparedness.” “We used the largest computers that are available and perhaps the most advanced algorithms to try and understand this really puzzling sequence of earthquakes that happened in California in 2019,” said Gabriel, currently an associate professor at the Institute of Geophysics and Planetary Physics at Scripps Oceanography. Their findings were recently published in the journal Nature. student at LMU, Taufiq Taufiqurrahman, and several co-authors. Scripps Oceanography seismologist Alice Gabriel, who previously worked at LMU, led the study along with her former Ph.D. The team used a powerful supercomputer that incorporated data-infused and physics-based models to identify the link between the earthquakes. To address these questions, a team of seismologists at Scripps Institution of Oceanography at UC San Diego and Ludwig Maximilian University of Munich (LMU) led a new study focused on the relationship between the two big earthquakes, which occurred along a multi-fault system. Why did it take 34 hours for the foreshock to trigger the mainshock? How did these earthquakes “jump” from one segment of a geologic fault system to another? Can earthquakes “talk” to one another in a dynamic sense? Researchers were baffled by the sequence of seismic activity. The 6.4 magnitude event that took place in Searles Valley was later categorized as a foreshock to the M7.1 event in Ridgecrest, Each earthquake was followed by a multitude aftershocks. They led to widespread structural damage, power failures, and injuries. These earthquakes, collectively referred to as the Ridgecrest earthquakes, were the most powerful to affect California in over two decades. The shaking was so intense that it was experienced by millions across California and also in nearby locations like Arizona, Nevada, and Baja California, Mexico. Roughly 34 hours later, on July 5, Ridgecrest, a neighboring city, experienced a 7.1 magnitude earthquake. In the early hours of July 4, 2019, a 6.4 magnitude earthquake rattled Searles Valley in California’s Mojave Desert, causing tremors felt throughout Southern California. ![]() Credit: Greg Abram and Francesca Samsel (Texas Advanced Computing Center), and Alice Gabriel (UC San Diego/Ludwig Maximilian University of Munich) Scientists use a supercomputer to unveil the intricate dynamics of multi-fault earthquake systems. Visualization of 15 TB of simulation data on a supercomputer. The pore water overpressure is likely achieved by fault zone compaction and hydraulic barriers.Propagation of seismic waves and unzipping of faults during the Ridgecrest, California, earthquake. The presence of thermal springs in the Argentera area indicates that the pore fluid is water. A calculation based on a pore fluid factor-differential stress failure mode diagram shows that the required excess pressure is comprised between 7 and 26 MPa. A 2-D analysis with a static coefficient of friction of 0.4 (consistent with the presence of phyllosilicate-rich gouges at depth) shows that the N130☎ fault is unfavourably oriented and that its reactivation is possible only with pore fluid pressure excess in the hypocentral region (6-7 km below surface). Inversion shows that the axis of the maximum principal stress σ1 is oriented nearly horizontal and at 63° from the fault plane and that the intermediate principal stress σ2 is almost parallel to the fault plane. The regional stress tensor in the vicinity of the fault is determined by inversion of focal mechanisms of the 38 events with largest magnitudes of the 2003-2004 swarm. Its reactivation is examined by a 2-D frictional fault analysis. A crustal-scale N130☎ strike-slip fault in the Ubaye-Argentera area, southwestern French-Italian Alps, was the locus of a seismic swarm in 2003-2004. ![]()
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