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

9526862约翰逊这项研究涉及获取亚利桑那州图森市附近的低角度圣丽塔正断层的中、高分辨率地震图像，以解决其与地表已发现的较浅、较陡、潜在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，孕震正断层的倾角从30度到70度不等。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)可能适应了大规模的地壳伸展。这些不同的观测结果经常被认为是低角度断层无震性滑动，或深部低角度断层在地表旋转成高角度的论点。这项工作将试图提供后一种论点的一个例子。这项研究是国家减少地震灾害计划的一部分。***

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. ***