High Resolution Seismic Imaging of the Santa Rita Fault, a Low-Angle Normal Fault Linked to Large-Magnitude Earthquakes

这项研究包括获取亚利桑那州图森附近的低角度圣丽塔正断层的中、高分辨率地震图像，以解决其与地表识别的更浅、更陡峭、潜在的地震活动断层的联系问题。伸展地体中大型（M=6或更大）正断层地震的震源机制表明，发震正断层的倾角在30至70度之间。与此同时，地质关系表明，大的、低角度的正断层（倾角小于30度）可能容纳了大规模的地壳伸展。这些不同的观测结果常常被以下观点所调和：低角度断层在地震中滑动，或者深层的低角度断层在地表旋转成高角度。本文将试图为后一种观点提供一个例子。这项研究是国家减少地震危害计划的一个组成部分。＊＊＊

9526862 Johnson This research involves the acquisition of medium and high- resolution seismic images of the low-angle Santa Rita normal fault, near Tucson, Arizona, to resolve the question of its connection to shallower, steeper, potentially seismogenically active faults identified at the surface. Focal mechanisms for large (M=6 or larger) normal-faulting earthquakes in extensional terranes suggest that seismogenic normal faults have dips that range from 30 to 70 degrees. At the same time, geologic relationships suggest that large, low-angle normal faults (dips of less than 30 degrees) may have accommodated large-scale crustal extension. These disparate observations are often reconciled by arguments that low-angle faults slip aseismically, or, low-angle faults at depth rotate to high angle at the surface. This work will attempt to provide an example of the latter argument. This research is a component of the National Earthquake Hazard Reduction Program. ***