Characterizing the Kathmandu Valley sediment response through strong motion recordings of the 2015 Gorkha earthquake sequence

S. Rajaure, D. Asimaki, E. M. Thompson, S. Hough, S. Martin, J. P. Ampuero, M. R. Dhital, A. Inbal, N. Takai, M. Shigefuji, S. Bijukchhen, M. Ichiyanagi, T. Sasatani, L. Paudel

研究成果: Contribution to journalArticle査読

17 被引用数 (Scopus)

抄録

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.

本文言語英語
ページ(範囲)146-157
ページ数12
ジャーナルTectonophysics
714-715
DOI
出版ステータス出版済み - 9 13 2017
外部発表はい

All Science Journal Classification (ASJC) codes

  • Earth-Surface Processes
  • Geophysics

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