Rainfall triggers more deep-seated landslides than Cascadia earthquakes in the Oregon Coast Range, USA

Science Advances
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Abstract

The coastal Pacific Northwest USA hosts thousands of deep-seated landslides. Historic landslides have primarily been triggered by rainfall, but the region is also prone to large earthquakes on the 1100-km-long Cascadia Subduction Zone megathrust. Little is known about the number of landslides triggered by these earthquakes because the last magnitude 9 rupture occurred in 1700 CE. Here, we map 9938 deep-seated bedrock landslides in the Oregon Coast Range and use surface roughness dating to estimate that past earthquakes triggered fewer than half of the landslides in the past 1000 years. We find landslide frequency increases with mean annual precipitation but not with modeled peak ground acceleration or proximity to the megathrust. Our results agree with findings about other recent subduction zone earthquakes where relatively few deep-seated landslides were mapped and suggest that despite proximity to the megathrust, most deep-seated landslides in the Oregon Coast Range were triggered by rainfall.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Rainfall triggers more deep-seated landslides than Cascadia earthquakes in the Oregon Coast Range, USA
Series title Science Advances
DOI 10.1126/sciadv.aba6790
Volume 6
Issue 38
Year Published 2020
Language English
Publisher American Association for the Advancement of Science
Contributing office(s) Earthquake Science Center
Description eaba6790, 11 p.
Country United States
State Oregon
Other Geospatial Oregon Coast Range
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