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Widespread initiation, reactivation, and acceleration of landslides in the northern California Coast Ranges due to extreme rainfall

Handwerger, Alexander L. and Fielding, Eric J. and Huang, Mong-Han and Bennett, Georgina L. and Liang, Cunren and Schulz, William H. (2019) Widespread initiation, reactivation, and acceleration of landslides in the northern California Coast Ranges due to extreme rainfall. Journal of Geophysical Research. Earth Surface, 124 (7). pp. 1782-1797. ISSN 2169-9003. doi:10.1029/2019JF005035.

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Episodically to continuously active slow‐moving landslides are driven by precipitation. Climate change, which is altering both the frequency and magnitude of precipitation worldwide, is therefore predicted to have a major impact on landslides. Here we examine the behavior of hundreds of slow‐moving landslides in northern California in response to large changes in annual precipitation that occurred between 2016 and 2018. We quantify the landslide displacement using repeat‐pass radar interferometry and pixel offset tracking techniques on a novel data set from the airborne NASA/JPL Uninhabited Aerial Vehicle Synthetic Aperture Radar. We found that 312 landslides were moving due to extreme rainfall during 2017, compared to 119 during 2016, which was the final year of a historic multiyear drought. However, with a return to below to average rainfall in 2018, only 146 landslides remained in motion. The increased number of landslides during 2017 was primarily accommodated by landslides that were smaller than the landslides that remained active between 2016 and 2018. Furthermore, by examining a subset of 51 landslides, we found that 49 had increased velocities during 2017 when compared to 2016. Our results show that slow‐moving landslides are sensitive to large changes in annual precipitation, particularly the smaller and thinner landslides that likely experience larger basal pore‐water pressure changes. Based on climate model predictions for the next century in California, which include increases in average annual precipitation and increases in the frequency of dry‐to‐wet extremes, we hypothesize that there will be an overall increase in landslide activity.

Item Type:Article
Related URLs:
URLURL TypeDescription
Handwerger, Alexander L.0000-0001-9235-3871
Fielding, Eric J.0000-0002-6648-8067
Huang, Mong-Han0000-0003-2331-3766
Bennett, Georgina L.0000-0002-4812-8180
Liang, Cunren0000-0003-3938-426X
Schulz, William H.0000-0001-9980-3580
Additional Information:© 2019 American Geophysical Union. Received 13 FEB 2019; Accepted 11 JUN 2019; Accepted article online 19 JUN 2019;Published online 10 JUL 2019. We thank Ben Mackey for sharing mapped landslide polygons. We thank Joshua Roering for discussions on the Eel River landslides. We thank Chris Milliner and Odin Marc for discussions on frequency‐magnitude relationships. We thank Yang Zheng and the UAVSAR flight and data processing teams for their help with acquiring and processing the data. We thank Jon Perkins, Harvey Kelsey, Jeff Coe, Amy East, and one anonymous reviewer for constructive reviews. Part of this research was sponsored by the NASA Earth Surface and Interior focus area and performed at the Jet Propulsion Laboratory, California Institute of Technology. A. L. H.'s research was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by Universities Space Research Association under contract with NASA. The precipitation data are provided by the PRISM Climate Group and may be downloaded online ( The PDSI data are provided by the WestWide Drought Tracker and may be downloaded through their website ( Lidar digital elevation models are provided by OpenTopography and may be downloaded online ( OpenTopography lidar data acquisition and processing was completed by the National Center for Airborne Laser Mapping (NCALM; NCALM funding was provided by NSF's Division of Earth Sciences, Instrumentation and Facilities Program EAR‐1043051. Topographic data are also provided by the German Aerospace Center (DLR) under data proposal DEM GEOL1478 awarded to A. L. H. To acquire these data, proposals may be submitted to the DLR online ( NASA/JPL UAVSAR data used in this study may be downloaded through their website ( The California geologic map is provided by the U.S. Geological Survey ( Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Group:Seismological Laboratory
Funding AgencyGrant Number
NASA Postdoctoral ProgramUNSPECIFIED
Subject Keywords:landslides; precipitation; climate; InSAR; California
Issue or Number:7
Record Number:CaltechAUTHORS:20190619-094141508
Persistent URL:
Official Citation:Handwerger, A. L., Fielding, E. J., Huang, M.‐H., Bennett, G. L., Liang, C., & Schulz, W. H. (2019). Widespread initiation, reactivation, and acceleration of landslides in the northern California Coast Ranges due to extreme rainfall. Journal Geophysical Research: Earth Surface, 124. 1782–1797
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96521
Deposited By: Tony Diaz
Deposited On:19 Jun 2019 17:14
Last Modified:16 Nov 2021 17:21

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