MSGID: 1:317/3 646ee46e   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    'Segment-jumping' ridgecrest earthquakes explored in new study    
    Seismologists use supercomputer to reveal complex dynamics of multi-fault   
   earthquake systems    
      
     Date:   
         May 24, 2023   
     Source:   
         University of California - San Diego   
     Summary:   
         Seismologists used a powerful supercomputer that incorporated data-   
         infused and physics-based models to identify the link between the   
         2019 Ridgecrest earthquakes.   
      
      
         Facebook Twitter Pinterest LinkedIN Email   
      
   ==========================================================================   
   FULL STORY   
   ==========================================================================   
   On the morning of July 4, 2019, a magnitude 6.4 earthquake struck the   
   Searles Valley in California's Mojave Desert, with impacts felt across   
   Southern California. About 34 hours later on July 5, the nearby city   
   of Ridgecrest was struck by a magnitude 7.1 earthquake, a jolt felt   
   by millions across the state of California and throughout neighboring   
   communities in Arizona, Nevada, and even Baja California, Mexico.   
      
   Known as the Ridgecrest earthquakes -- the biggest earthquakes to   
   hit California in more than 20 years -- these seismic events resulted   
   in extensive structural damage, power outages, and injuries. The M6.4   
   event in Searles Valley was later deemed to be the foreshock to the M7.1   
   event in Ridgecrest, which is now considered to be the mainshock. Both   
   earthquakes were followed by a multitude of aftershocks.   
      
   Researchers were baffled by the sequence of seismic activity. 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?   
   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. The team used a   
   powerful supercomputer that incorporated data-infused and physics-based   
   models to identify the link between the earthquakes.   
      
   Scripps Oceanography seismologist Alice Gabriel, who previously worked   
   at LMU, led the study along with her former PhD student at LMU, Taufiq   
   Taufiqurrahman, and several co-authors. Their findings were published   
   May 24 in the journal Natureonline, and will appear in the print edition   
   June 8.   
      
   "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. "High-performance computing   
   has allowed us to understand the driving factors of these large events,   
   which can help inform seismic hazard assessment and preparedness."   
   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. For example, the Turkey-Syria   
   earthquake doublet that occurred on Feb. 6, 2023, resulted in significant   
   loss of life and widespread damage. This event was characterized by   
   two separate earthquakes that occurred only nine hours apart, with both   
   breaking across multiple faults.   
      
   During the 2019 Ridgecrest earthquakes, which originated in the   
   Eastern California Shear Zone along a strike-slip fault system, the   
   two sides of each fault moved mainly in a horizontal direction, with no   
   vertical motion. The earthquake sequence cascaded across interlaced and   
   previously unknown "antithetic" faults, minor or secondary faults that   
   move at high (close to 90 degrees) angles to the major fault. Within the   
   seismological community, there remains an ongoing debate on which fault   
   segments actively slipped, and what conditions promote the occurrence   
   of cascading earthquakes.   
      
   The new study presents the first multi-fault model that unifies   
   seismograms, tectonic data, field mapping, satellite data, and other   
   space-based geodetic datasets with earthquake physics, whereas previous   
   models on this type of earthquake have been purely data-driven.   
      
   "Through the lens of data-infused modeling, enhanced by the capabilities   
   of supercomputing, we unravel the intricacies of multi-fault conjugate   
   earthquakes, shedding light on the physics governing cascading rupture   
   dynamics," said Taufiqurrahman.   
      
   Using the supercomputer SuperMUC-NG at the Leibniz Supercomputing Centre   
   (LRZ) in Germany, the researchers revealed that the Searles Valley and   
   Ridgecrest events were indeed connected. The earthquakes interacted   
   across a statically strong yet dynamically weak fault system driven by   
   complex fault geometries and low dynamic friction.   
      
   The team's 3-D rupture simulation illustrates how the faults considered   
   strong prior to an earthquake can become very weak as soon as there is   
   fast earthquake movement and explain the dynamics of how multiple faults   
   can rupture together.   
      
   "When fault systems are rupturing, we see unexpected interactions. For   
   example, earthquake cascades, which can jump from segment to segment,   
   or one earthquake causing the next one to take an unusual path. The   
   earthquake may become much larger than what we would've expected," said   
   Gabriel. "This is something that is challenging to build into seismic   
   hazard assessments."  According to the authors, their models have the   
   potential to have a "transformative impact" on the field of seismology   
   by improving the assessment of seismic hazards in active multi-fault   
   systems that are often underestimated.   
      
   "Our findings suggest that similar kinds of models could incorporate   
   more physics into seismic hazard assessment and preparedness," said   
   Gabriel. "With the help of supercomputers and physics, we have unraveled   
   arguably the most detailed data set of a complex earthquake rupture   
   pattern."  The study was supported by the European Union's Horizon 2020   
   Research and Innovation Programme, Horizon Europe, the National Science   
   Foundation, the German Research Foundation, and the Southern California   
   Earthquake Center.   
      
   In addition to Gabriel and Taufiqurrahman, the study was co-authored   
   by Duo Li, Thomas Ulrich, Bo Li, and Sara Carena of Ludwig Maximilian   
   University of Munich, Germany; Alessandro Verdecchia with McGill   
   University in Montreal, Canada, and Ruhr-University Bochum in Germany;   
   and Frantisek Gallovic of Charles University in Prague, Czech Republic.   
      
       * RELATED_TOPICS   
             o Earth_&_Climate   
                   # Earthquakes # Natural_Disasters # Tsunamis   
             o Computers_&_Math   
                   # Computer_Modeling # Computers_and_Internet #   
                   Information_Technology   
             o Fossils_&_Ruins   
                   # Origin_of_Life # Evolution # Charles_Darwin   
       * RELATED_TERMS   
             o Moment_magnitude_scale o Seismometer o Air_engine o   
             Mathematical_model o Meteorology o Numerical_weather_prediction   
             o Quantum_mechanics o Scientific_visualization   
      
   ==========================================================================   
   Story Source: Materials provided by   
   University_of_California_-_San_Diego. Original written by Brittany   
   Hook. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Taufiq Taufiqurrahman, Alice-Agnes Gabriel, Duo Li, Thomas Ulrich,   
      Bo Li,   
         Sara Carena, Alessandro Verdecchia, Frantisek   
         Gallovič. Dynamics, interactions and delays of the   
         2019 Ridgecrest rupture sequence. Nature, 2023; DOI:   
         10.1038/s41586-023-05985-x   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230524181903.htm   
      
   --- up 1 year, 12 weeks, 2 days, 10 hours, 50 minutes   
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)   
   SEEN-BY: 15/0 106/201 114/705 123/120 153/7715 218/700 226/30 227/114   
   SEEN-BY: 229/110 112 113 307 317 400 426 428 470 664 700 291/111 292/854   
   SEEN-BY: 298/25 305/3 317/3 320/219 396/45   
   PATH: 317/3 229/426