Moderate-magnitude seismicity remotely triggered in the Taiwan region by large earthquakes around the Philippine Sea plate

Abstract

Seismicity in the Taiwan region was studied before and after the 12 largest seismic events with body-wave magnitudes exceeding 6.5, occurring around the Philippine Sea plate in the 1973 to 1994 period. The total local seismicity rate involving events with magnitudes as small as 2.0 was not affected by remote large events. However, the number of local earthquakes with magnitude ML ≧ 4.5 in the 15 days following a large event exceeded the number before it in 9 out of 12 cases studied. When earthquakes with ML ≧ 4.0 were considered, then 10 cases showed an increase in seismic activity after the big event. This suggests a 75 to 83% probability of remote triggering.

Dynamically triggered seismicity on a tectonic scale: A review

“…The 2014 South Napa, California, M w 6.0 earthquake immediately triggered some tremors, and it was also found that some tremors had a certain time delay, with the largest tremor occurring 12 h after the main seismic surface wave passed through (Peng et al, 2015). In addition, delayed triggering also occurs in Taiwan, China (Beresnev & Wen, 1995; Wen et al, 1996), Gulf of Mexico (Singh et al, 1998), and other places.The phenomenon of delayed dynamic stress triggering of seismic events is common, and the reasons may be as follows: First, the stress in the triggered area may be in a subcritical state, and the dynamic Coulomb stress generated by strong seismic surface waves has not accumulated to the level of rock shear strength in the triggered area, so further stress accumulation is required. Second, according to the principle of subcritical crack propagation, the strain band at the crack tip weakens under the action of environmental media (such as water, air, etc.…”

“…The 2014 South Napa, California, M w 6.0 earthquake immediately triggered some tremors, and it was also found that some tremors had a certain time delay, with the largest tremor occurring 12 h after the main seismic surface wave passed through (Peng et al, 2015). In addition, delayed triggering also occurs in Taiwan, China (Beresnev & Wen, 1995; Wen et al, 1996), Gulf of Mexico (Singh et al, 1998), and other places.…”