Basic data features and results from a spatially dense seismic array on the San Jacinto fault zone
Basic data features and results from a spatially dense seismic array on the San Jacinto fault zone
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DOI：
10.1093/gji/ggv142
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发表时间：
2015-07-01
影响因子：
2.8
通讯作者：
Barklage, Mitchell
中科院分区：
文献类型：
--
作者：
Ben-Zion, Yehuda;Vernon, Frank L.;Barklage, Mitchell
我们讨论了横跨南加州圣哈辛托断层损伤区的空间密集节点阵列在>；4周内记录的地震图的几个突出方面，以及一些实例结果。这些波形包含许多尖峰和爆发的高频波(高达记录的200赫兹)，部分是由地壳浅层的微小破裂事件产生的。该阵列的高空间密度便于在一天内探测到120次当地小地震，其中大部分没有被周围的ANZA和南加州区域网络探测到。波束形成结果确定了在1-10赫兹频率范围内占主导地位的可能正在进行的文化噪声源和在20-40赫兹频率范围内占主导地位的可能正在进行的地震源。地震记录的匹配场处理和反投影提供了交替的事件位置。实验期间不同站点的中值噪声水平、Betsy枪击产生的波以及附近地震产生的波场一致地指向断层上的几个结构单元。地震圈闭构造和局部沉积盆地产生了局部运动放大和比邻区更强的衰减。在近距离台站记录的高频噪声的交叉相关提供了跨断层带的地下物质的结构图像。高空间密度和宽频率范围的数据可用于额外的高分辨率研究浅层地壳的结构和震源性质。
We discuss several outstanding aspects of seismograms recorded during >4 weeks by a spatially dense Nodal array, straddling the damage zone of the San Jacinto fault in southern California, and some example results. The waveforms contain numerous spikes and bursts of high-frequency waves (up to the recorded 200 Hz) produced in part by minute failure events in the shallow crust. The high spatial density of the array facilitates the detection of 120 small local earthquakes in a single day, most of which not detected by the surrounding ANZA and regional southern California networks. Beamforming results identify likely ongoing cultural noise sources dominant in the frequency range 1-10 Hz and likely ongoing earthquake sources dominant in the frequency range 20-40 Hz. Matched-field processing and back-projection of seismograms provide alternate event location. The median noise levels during the experiment at different stations, waves generated by Betsy gunshots, and wavefields from nearby earthquakes point consistently to several structural units across the fault. Seismic trapping structure and local sedimentary basin produce localized motion amplification and stronger attenuation than adjacent regions. Cross correlations of high-frequency noise recorded at closely spaced stations provide a structural image of the subsurface material across the fault zone. The high spatial density and broad frequency range of the data can be used for additional high resolution studies of structure and source properties in the shallow crust.