Abstract: Taking five major, M≥7 earthquakes occurred in the northern section of South-north seismic zone, an inter-region between northeast Tibetan Plateau and North China block, during 360a from 1561 to 1920 as examples, the Coulomb failure stress changes (ΔCFS's) caused by the previous earthquakes are calculated on the rakes of fault surfaces of the later earthquakes to study earthquake triggering by building seismotectonic models, based on our knowledge about the seismogenic faults. The results suggest that, after the 1561 Luoshan M 7^1/4 earthquake happened, the next four events would occur in the stress triggering area (△CFS>0). △CFS's related to the Yunwushan fault, the Helanshan fault and the Haiyuan fault are larger than 0.2×10^5 Pa, surpassing the triggering threshold of 0.1×10 Pa. It means that the distribution of △CFS has a significant indication on the location of earthquakes in the future. According to △CFS and tectonic stress accumulation rate (δτ), the periods reduced by △CFS are calculated, which can be as large as 160a for the corresponding earthquakes. The triggering caused by the previous earthquake to the next shortens the accumulation time of earthquake re occurrence, which makes the earthquake happen ahead. It can cause that earthquake activity shows temporally the feature of quasi-cycle for a seismogenic fault and spatially the phenomenon of clustering for different seismogenic faults. This study contributes to our understandings about fault interaction, relationship among strong earthquakes even at different seismotectonic provinces and seismic risky areas in the future.
Publication Year: 2008
Publication Date: 2008-11-15
Language: en
Type: article
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