Characterizing the Kathmandu Valley sediment response through strong motion recordings of the 2015 Gorkha earthquake sequence
Characterizing the Kathmandu Valley sediment response through strong motion recordings of the 2015 Gorkha earthquake sequence
复制标题
DOI：
10.1016/j.tecto.2016.09.030
复制
发表时间：
2017-09-13
期刊：
影响因子：
2.9
通讯作者：
Paudel, L.
中科院分区：
文献类型：
--
作者：
Rajaure, S.;Asimaki, D.;Paudel, L.
我们分析了强震记录和高速率GPS测量的M 7.8 Gorkha主震，M 7.3 Dolakha，和两个中等余震事件记录在四个站的加德满都盆地沉积物，一个岩石露头。所有四个事件的土壤记录显示，在0.1 - 2.5 Hz频率范围内的多个频率下，相对于岩石场地，有系统的放大作用，而在更高的频率（> 2.5 - 10 Hz）下，有去放大作用。M7.8和M7.3事件的土-岩放大率相对于两个中等事件的比率具有较低的振幅和频率峰值，这种效应可能暗示非线性场地响应。此外，与地面运动预测方程的比较表明，1）土壤和岩石主震记录都严重耗尽了高频，2）在余震中不存在高频的耗尽。这些观测结果表明，高频衰减还与简化的地面运动预测方程未捕获的源特性有关，并暗示正在修订的地震危险性分析模型-可能通过将孤立的高频辐射源与长周期分量分开处理，以捕获大震级近源事件，如2015年廓尔喀主震。(C)2016爱思唯尔B.V.保留所有权利。
We analyze strong motion records and high-rate GPS measurements of the M 7.8 Gorkha mainshock, M 7.3 Dolakha, and two moderate aftershock events recorded at four stations on the Kathmandu basin sediments, and one on rock-outcrop. Recordings on soil from all four events show systematic amplification relative to the rock site at multiple frequencies in the 0.1-2.5 Hz frequency range, and de-amplification of higher frequencies (>2.5-10 Hz). The soil-to-rock amplification ratios for the M 7.8 and M 7.3 events have lower amplitude and frequency peaks relative to the ratios of the two moderate events, effects that could be suggestive of nonlinear site response. Further, comparisons to ground motion prediction equations show that 1) both soil and rock mainshock recordings were severely depleted of high frequencies, and 2) the depletion at high frequencies is not present in the aftershocks. These observations indicate that the high frequency deamplification is additionally related to characteristics of the source that are not captured by simplified ground motion prediction equations, and allude to seismic hazard analysis models being revised - possibly by treating isolated high frequency radiation sources separately from long period components to capture large magnitude near-source events such as the 2015 Gorkha mainshock. (C) 2016 Elsevier B.V. All rights reserved.