Experimental investigation of strong ground motion due to thrust fault earthquakes
Experimental investigation of strong ground motion due to thrust fault earthquakes
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逆冲断层地震强地震动实验研究
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
D. Oglesby
中科院分区：
文献类型：
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作者：
V. Gabuchian;A. Rosakis;N. Lapusta;D. Oglesby
逆冲断层地震是在以前用于研究模拟走滑地震事件的实验室地震装置中研究的。动态模式II破裂产生沿着预先存在的故障在模拟材料，Homalite H-100，和他们的相互作用与自由表面进行了研究的亚瑞利和超剪切破裂速度。高速数字摄影和激光测速仪诊断协同使用，以识别和研究由所产生的破裂的各种特征引起的地面速度特征。获得的亚瑞利和超剪切破裂的表面法向运动显示出上盘和下盘之间的显著不对称性，上盘经历了更大的速度振幅。不同台站的表面速度迹线的主要特征可以通过计算的各种波和锋的到达来解释-马赫锥、P波和S波以及亚瑞利特征。在亚瑞利和超剪切的情况下，破裂尖端的到来产生一个突出的瑞利波沿沿着模拟地球表面。超剪切地震具有较大的地震动剖面振幅。地表运动记录中的所有特征都随着距断层迹线距离的增加而衰减和加宽。对应于马赫阵面到达的信号随距离衰减的速率比亚瑞利破裂的慢。上倾超剪切破裂到达自由表面时，产生了具有马赫锥的下倾传播滑移特征。这些附加的马赫锋进一步放大了悬挂壁和下盘的地面震动。
Thrust fault earthquakes are studied in a laboratory earthquake setup previously used to investigate analog strike‐slip seismic events. Dynamic mode II ruptures are generated along preexisting faults in an analog material, Homalite H‐100, and their interaction with the free surface is studied for both sub‐Rayleigh and supershear rupture speeds. High‐speed digital photography and laser velocimeter diagnostics are used synergistically to identify and study the ground velocity signatures caused by the various features of the generated ruptures. The obtained surface‐normal motions of both sub‐Rayleigh and supershear ruptures show substantial asymmetry between the hanging and footwall, with the hanging wall experiencing much larger velocity amplitudes. The main features of the surface velocity traces at various stations can be explained by the calculated arrivals of various waves and fronts—Mach cones, Pand S waves, and sub‐Rayleigh features. In both the sub‐Rayleigh and supershear cases, the arrival of the rupture tip generates a prominent Rayleigh wave traveling along the simulated Earth's surface. Supershear events feature larger amplitudes of ground shaking profiles. All signatures in the surface motion records attenuate and broaden with increasing distance from the fault trace. The signatures corresponding to the arrival of the Mach fronts attenuate with distance at a slower rate than those from sub‐Rayleigh ruptures. The arrival of the updip supershear rupture at the free surface creates a downdip propagating slip feature with its own Mach cone. These additional Mach fronts further amplify ground shaking on the hanging and footwalls.