Use of reflection phases on microearthquake seismograms to map an unusual discontinuity beneath the Rio Grande rift
Use of reflection phases on microearthquake seismograms to map an unusual discontinuity beneath the Rio Grande rift
复制标题
利用微地震地震图的反射相位来绘制里奥格兰德裂谷下方不寻常的不连续性图
DOI：
10.1785/bssa0636-12021
复制
发表时间：
1973
影响因子：
3
通讯作者：
T. Toppozada
中科院分区：
文献类型：
--
作者：
A. Sanford;Ö. Alptekin;T. Toppozada
位于新墨西哥州索科罗附近格兰德裂谷或毗邻该裂谷的台站记录的微震记录，在直接S之后经常有两个尖锐的脉冲震相。这些震相被确定为SxP和SxS反射，来自一个尖锐的不连续面，其深度在Socorro之下18公里，并以近6°的角度向北倾斜30公里。再往北，倾角变陡，因此在距离索科罗60公里的地方，深度约为30公里。SxP与SxS振幅之比结合平面波反射理论表明，在不连续面下存在一个非常低的刚性带。大的SxS幅度被认为是跨不连续面上大的速度差和断层机制的结果，该断层机制向下比从震源向外辐射更多的S波能量。
Microearthquake seismograms recorded by stations located in or bordering the Rio Grande rift near Socorro, New Mexico, frequently have two sharp impulsive phases following direct S. These phases have been identified as SxP and SxS reflections from a sharp discontinuity that has a depth beneath Socorro of 18 km and dips northward at an angle near 6° for a distance of 30 km. Farther north, the dip steepens so that at a distance of 60 km from Socorro the depth is about 30 km. Ratios of SxP to SxS amplitudes in conjunction with plane-wave reflection theory indicate a zone of very low rigidity beneath the discontinuity. Large SxS amplitudes are believed to be the result of the large velocity contrast across the discontinuity and a fault mechanism that radiates more S-wave energy downward than outward from the focus.