The space and time distribution characteristics of the shear stress field for the sequence of the Wuding earthquake |
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| Authors: | JIA-ZHENG QIN XIAO-DONG QIAN JUN-WEI ZHANG QING-YIN XIE |
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| Institution: | Seismological Bureau of Yunnan Province, Kunming 650041, China |
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| Abstract: | Follow Chen and Duda’s model of spectral fall-off of ω3, the dependence of peak parameters of ground motion, peak displacement d
m, peak velocity v
m and peak acceleration a
m, upon the environment stress τ
0-values are studied using near source seismic digital recordings for the sequence of the Wuding, Yunnan, M=6.5 earthquake, in which, as a new thought, the peak parameters are assumed to be related to the medium Q-value. Three formulae for estimating the environment stress τ
0-values by the peak parameters of three types of ground motions are derived. Using these formulae, the environment stress
τ
0-values are calculated for the sequence of the Wuding earthquake. The result show that τ
0-values calculated by the three formulae are constant largely, the averages of τ
0 are in the range of 5.0–35 MPa for most earthquakes. It belongs to the high-stress earthquakes sequence: the high-stress
values are restricted to the relatively small area closely near to the epicenter of the main shock. The fine distribution
structure for the contours of the environment stress τ
0-values is related closely to the strong aftershocks. The analysis of spatial and temporal feature of τ
0-values suggests that the earthquakes sequence in a rupture process generated at the specific intersection zone of seismo-tectonics
under high-stress background.
This study is supported by the Chinese Joint Seismological Science Foundation and the key project during Ninth Five-Year Plan
from China Seismological Bureau. |
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| Keywords: | digital seismogram peak parameters of ground motion near-source environment stress char acteristics seismic sequence of Wuding earthquake |
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