Large accelerations and tectonic setting of the May 1993 Shumagin Islands earthquake sequence

Author:

Abers Geoffrey A.1,Beavan John1,Horton Steven1,Jaumé Steven1,Triep Enrique1

Affiliation:

1. Lamont-Doherty Earth Observatory of Columbia University Palisades New York

Abstract

Abstract Variability of earthquake rupture can lead to large disparities between expected and observed ground motion. To better understand the range of ground motions generated by subduction zone earthquakes, we examine teleseismic and nearsource strong-motion records from an interplate thrust earthquake sequence that occurred near the Shumagin Islands, Alaska Peninsula, in May 1993. The two largest events show source depths of 36 km (May 13) and 42 km (May 25) from inversion of teleseismic waveforms, which place them in the deepest part of the interplate thrust zone. This inference is verified by single-station epicenter estimates, derived from P-wave polarization and S-P times, and by the focal mechanisms. The 13 May 1993 mainshock (MS 6.9) shows peak accelerations of 0.7 to 1.4 m · sec−2 within 75 km of the epicenter, consistent with scaling relations observed elsewhere. The largest aftershock, 25 May (MW 6.1), shows peak acceleration near 8 m · sec−2 at a station 25 km away. The 8 m · sec−2 acceleration is far larger than expected for an earthquake of this size and depth and is perhaps the largest recorded in Alaska. Simple explanations such as site effects and rupture directivity cannot fully account for the anomalous accelerations. The short rupture time of the 25 May event (∼2.8 sec) contributes to high accelerations but cannot explain the factor of 12 variability observed in peak acceleration near the epicenter. Unusual focusing effects and rupture patterns are suspected but cannot be confirmed. Whatever the cause, the unusually high accelerations demonstrate that deep and moderate-sized earthquakes can occasionally produce significant ground motions in subduction zones.

Publisher

Seismological Society of America (SSA)

Subject

Geochemistry and Petrology,Geophysics

Cited by 3 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3