Monsoonal control on a delayed response of sedimentation to the 2008 Wenchuan earthquake

Date

2019-06-12

Authors

Zhang, Fei
Jin, Zhangdong
West, A. Joshua
An, Zhisheng
Hilton, Robert
Wang, Jin
Li, Gen
Densmore, Alexander L.
Yu, Jimin
Qiang, Xiaoke

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Publisher

American Association for the Advancement of Science

Abstract

Infrequent extreme events such as large earthquakes pose hazards and have lasting impacts on landscapes and biogeochemical cycles. Sediments provide valuable records of past events, but unambiguously identifying event deposits is challenging because of nonlinear sediment transport processes and poor age control. Here, we have been able to directly track the propagation of a tectonic signal into stratigraphy using reservoir sediments from before and after the 2008 Wenchuan earthquake. Cycles in magnetic susceptibility allow us to define a precise annual chronology and identify the timing and nature of the earthquake’s sedimentary record. The grain size and Rb/Sr ratio of the sediments responded immediately to the earthquake. However, the changes were muted until 2 years after the event, when intense monsoonal runoff drove accumulation of coarser grains and lower Rb/Sr sediments. The delayed response provides insight into how climatic and tectonic agents interact to control sediment transfer and depositional processes.

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Source

Science Advances

Type

Journal article

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Access Statement

Open Access

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Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).

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