Could the abnormal seismicity increase triggered remotely by great earthquakes be used to judge the regional earthquake risk?
Abstract
We study the possible dynamic triggering effect in Northern China, including Tangshan area,
when the Japan Tohoku M_w 9.0 earthquake happened at March 11th, 2011(In short, Japan Tohoku earthquake).
We use Time-Space Epidemic Type Aftershock Sequence Model (Time-Space ETAS model) as the seismicity statistic model in this research,
using Stochastic Declustering method and Gauss Kernel function to get Time- Space background seismicity variation image on the target area.
Thus this research may find out whether the area with large co-seismic displacement would have sudden abnormal seismicity increase.
As a result, the Japan Tohoku earthquake has little effect on the total and background seismicity of Tangshan area, which means that the seismic structure of Tangshan area is fundamentally stable.
However, when we did research on the possible dynamic triggering effect in Southwestern China,
we found that seismicity on some place in Sichuan and Yunnan has sudden abnormally increased almost at the same time when 2004 Sumatra M_w 9.2 earthquake (In short, 2004 Sumatra earthquake) happened.
That is the statistic phenomenon which shows the existence of co-seismic dynamic triggering.
This research helps to find out the exact position of the high abnormal seismicity area in its time image.
Besides, this time image can also help to detect whether this high “abnormal” seismicity in the picture is really abnormal or is triggered by certain large earthquake or not.
