10:45 AM - 11:00 AM
[SSS08-05] Quantitative study on dynamic triggering based on
seismicity changes over Japanese Islands associated with teleseismic earthquakes
Keywords:dynamic triggering , Japanese Islands, seismicity changes, triggering intensity
Dynamic triggering (far-field triggering) of earthquakes is a natural phenomenon in which large surface
waves from large earthquakes remotely trigger other earthquakes due to stress perturbations. The dynamic triggering of earthquakes due to many large earthquakes has been reported
by previous studies, but further investigation into quantitative analyses on seismicity changes associated with dynamic triggering is required to elucidate the triggering mechanism.
In this study, changes in the seismicity rate over the Japanese Islands associated with distant earthquakes
are quantitatively evaluated using the triggering intensity n (van der Elst & Brodsky, 2010).The period of analysing seismic activity is divided into 1997-2010 and 2012-2021. The n-value
indicates the fractional seismicity rate changes before and after the arrival of surface waves from distant
earthquakes, where n larger than 0 and n smaller than 0 mean the increase and decrease in seismicity
rate, respectively.We use teleseismic events(shallower than 30km, M6 or greater) from the ANSS Earthquake Catalogue and regional earthquakes in the Japanese Islands from the JMA earthquake catalog (shallower than 30 km in depth, considering Mc). The n-value for every grid area is calculated based on the method by van der Elst and Brodsky (2010). In addition, we examined the relationship between Peak Ground Velocity (PGV) and n-value.
Large n-values were found in regions that experienced significant earthquakes and volcanic eruptions, and geothermal regions. We found a high n-value for large PGV, however, dynamic triggering in the Japanese Islands is less likely to occur compared to southern California.
waves from large earthquakes remotely trigger other earthquakes due to stress perturbations. The dynamic triggering of earthquakes due to many large earthquakes has been reported
by previous studies, but further investigation into quantitative analyses on seismicity changes associated with dynamic triggering is required to elucidate the triggering mechanism.
In this study, changes in the seismicity rate over the Japanese Islands associated with distant earthquakes
are quantitatively evaluated using the triggering intensity n (van der Elst & Brodsky, 2010).The period of analysing seismic activity is divided into 1997-2010 and 2012-2021. The n-value
indicates the fractional seismicity rate changes before and after the arrival of surface waves from distant
earthquakes, where n larger than 0 and n smaller than 0 mean the increase and decrease in seismicity
rate, respectively.We use teleseismic events(shallower than 30km, M6 or greater) from the ANSS Earthquake Catalogue and regional earthquakes in the Japanese Islands from the JMA earthquake catalog (shallower than 30 km in depth, considering Mc). The n-value for every grid area is calculated based on the method by van der Elst and Brodsky (2010). In addition, we examined the relationship between Peak Ground Velocity (PGV) and n-value.
Large n-values were found in regions that experienced significant earthquakes and volcanic eruptions, and geothermal regions. We found a high n-value for large PGV, however, dynamic triggering in the Japanese Islands is less likely to occur compared to southern California.