Evolution of 3D velocity structure before Dayao M=6.2 and M=6.1 earthquakes in 2003
Evolution of 3D velocity structure before Dayao M=6.2 and M=6.1 earthquakes in 2003
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DOI：
10.1007/s11589-007-0021-3
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发表时间：
2007
影响因子：
--
通讯作者：
Longwen Zhou;Jie Liu;Xiao-dong Zhang
中科院分区：
文献类型：
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作者：
Longwen Zhou;Jie Liu;Xiao-dong Zhang
本文对年尺度的地壳速度结构进行成像，以确定2003年大姚地震前三维速度结构的演化，并讨论了介质物理变化与地震发生原因之间的关系。棋盘分辨率测试表明，大窑周围15 km深度的空间分辨率约为0.6。误差分析表明，焦点区域的误差（约0.02 km/s）远小于速度变化幅度（约0.15 km/s）。研究结果表明，大姚地震前形成了一个北北西走向的高低速交接带，其走向与大姚地震余震分布及震源机制基本一致，震源位于交接带的高速侧。此外，大姚地震后震源下方存在低速体。速度结构的演化为讨论地震孕育和发生的环境提供了限制。
In this paper the crustal velocity structure are imaged at the annual scale for determining the evolution of 3D velocity structure before the Dayao earthquakes in 2003, and the relation between physical variation of medium and cause of earthquake occurrence is discussed. Checkerboard resolution tests show that the spatial resolution at 15 km depth is approximate 0.6 around Dayao. Error analyses show that the error (Approximate 0.02 km/s) at the focus area is far smaller than the magnitude (approximate 0.15 km/s) of velocity variation. Results of the studies show that a NNW-striking juncture zone of high-and low-velocity is formed before Dayao earthquake, whose strike is basically consistent with that of aftershock distribution of Dayao earthquakes and the focal mechanism, and the hypocenters lie on the high-velocity side of juncture zone. Furthermore, there is a low-velocity body under the hypocenters after Dayao earthquakes. The evolution of velocity structure provides restriction for discussing the circumstances of earthquake gestating and occurring.