Seismic imaging reveals a strain-partitioned sliver and nascent megathrust at an incipient subduction zone in the northeast Pacific

IF 11.7 1区综合性期刊 Q1 MULTIDISCIPLINARY SCIENCES

Science Advances Pub Date : 2025-07-18 DOI:10.1126/sciadv.adt3003

Collin C. Brandl, Lindsay L. Worthington, Emily C. Roland, Maureen A. L. Walton, Mladen R. Nedimović, Andrew C. Gase, Olumide Adedeji, Jose Castillo Castellanos, Benjamin J. Phrampus, Michael G. Bostock, Kelin Wang, Sarah Jaye Oliva

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Abstract

The Queen Charlotte plate boundary (QCPB), a transform separating the Pacific and North American plates, accommodates ~55 millimeters per year of motion, is a source of large earthquakes in the northeast Pacific, and may be a modern site of subduction initiation. The southern QCPB experiences oblique convergence, showcased by the 1949 magnitude (M) 8.1 strike-slip earthquake and the 2012 M7.8 tsunamigenic thrust earthquake, both offshore Haida Gwaii, British Columbia. We present seismic reflection images of the southern QCPB, which constrain the crustal structure in unprecedented detail. The Queen Charlotte Terrace is underthrust by oceanic crust topped by a throughgoing, low-angle plate-boundary thrust, which ruptured in the 2012 earthquake. The Queen Charlotte Terrace is analogous to strain-partitioned, thin-skinned forearc slivers seen at oblique subduction zones, captured between a localized plate-boundary thrust and a mature strike-slip fault. Our imaging suggests that the system rapidly evolved from distributed to partitioned strain and is currently an incipient subduction zone.

Abstract Image

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地震成像显示，在东北太平洋的一个早期俯冲带上，有一条应变分割的银条和新生的巨型逆冲构造

夏洛特女王板块边界（Queen Charlotte plate boundary， QCPB）是分隔太平洋板块和北美板块的一个变换，每年可容纳约55毫米的运动，是东北太平洋大地震的一个震源，可能是俯冲起始的一个现代地点。加拿大不列颠哥伦比亚省海达瓜伊海域发生了1949年8.1级走滑地震和2012年7.8级海啸性逆冲地震。我们提出了QCPB南部的地震反射图像，这些图像以前所未有的细节约束了地壳结构。夏洛特女王露台位于海洋地壳的下方，顶部是一个贯穿的低角度板块边界逆冲，在2012年的地震中破裂。夏洛特女王台地类似于在斜俯冲带看到的应变分割的薄皮前弧条，位于局部板块边界逆冲断层和成熟走滑断层之间。我们的成像表明，该系统从分布应变迅速演变为分区应变，目前是一个早期的俯冲带。

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来源期刊

Science Advances 综合性期刊-综合性期刊

CiteScore

21.40

自引率

1.50%

发文量

1937

审稿时长

29 weeks

期刊介绍： Science Advances, an open-access journal by AAAS, publishes impactful research in diverse scientific areas. It aims for fair, fast, and expert peer review, providing freely accessible research to readers. Led by distinguished scientists, the journal supports AAAS's mission by extending Science magazine's capacity to identify and promote significant advances. Evolving digital publishing technologies play a crucial role in advancing AAAS's global mission for science communication and benefitting humankind.