Coseismic landslides reveal near-surface rock strength in a high-relief tectonically active setting

Geology
University of Michigan
By: , and 

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Abstract

We present quantitative estimates of near-surface rock strength relevant to landscape evolution and landslide hazard assessment for 15 geologic map units of the Longmen Shan, China. Strength estimates are derived from a novel method that inverts earthquake peak ground acceleration models and coseismic landslide inventories to obtain material proper- ties and landslide thickness. Aggregate rock strength is determined by prescribing a friction angle of 30° and solving for effective cohesion. Effective cohesion ranges are from 70 kPa to 107 kPa for 15 geologic map units, and are approximately an order of magnitude less than typical laboratory measurements, probably because laboratory tests on hand-sized specimens do not incorporate the effects of heterogeneity and fracturing that likely control near-surface strength at the hillslope scale. We find that strength among the geologic map units studied varies by less than a factor of two. However, increased weakening of units with proximity to the range front, where precipitation and active fault density are the greatest, suggests that cli- matic and tectonic factors overwhelm lithologic differences in rock strength in this high-relief tectonically active setting.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Coseismic landslides reveal near-surface rock strength in a high-relief tectonically active setting
Series title Geology
DOI 10.1130/G36080.1
Volume 43
Issue 1
Year Published 2014
Language English
Publisher Geological Society of America
Publisher location Boulder, CO
Contributing office(s) Office of the AD Hazards
Description 4 p.
First page 11
Last page 14
Online Only (Y/N) N
Additional Online Files (Y/N) N
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