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Fault-zone controls on the spatial distribution of slow-moving landslides

Scheingross, Joel S. and Minchew, Brent M. and Mackey, Benjamin H. and Simons, Mark and Lamb, Michael P. and Hensley, Scott (2013) Fault-zone controls on the spatial distribution of slow-moving landslides. Geological Society of America Bulletin, 125 (3-4). pp. 473-489. ISSN 0016-7606. doi:10.1130/B30719.1.

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Slow-moving landslides (earthflows) can dominate hillslope sediment flux and landscape erosion in hilly terrain with mechanically weak, fine-grained rock. Controls on the occurrence of slow-moving landslides are poorly constrained and need to be understood for landscape evolution models, sediment budgets, and infrastructure and hazards planning. Here, we use airborne interferometric synthetic aperture radar (InSAR) and aerial photographs to document 150 previously unidentified active earthflows along the central, creeping portion of the San Andreas fault, California. The earthflows move seasonally in response to winter rainfall, occur on hillslopes at ∼20%–40% gradients (less than typically associated with rapid, catastrophic landslides), and have similar morphological characteristics to earthflows in different climatic and tectonic settings. Although our data extend up to 10 km from the fault trace, ∼75% of detected landslides occur within 2 km of the active fault. Topographic, precipitation, and rock type metrics alone are not enough to explain the observed spatial distribution of earthflows. Instead, we hypothesize that earthflows cluster near the creeping San Andreas fault because of a fault-induced zone of reduced bulk-rock strength that increases hillslope susceptibility to failure. In addition, similar lithology, topography, and climate exist north of the creeping section of the fault, yet earthflows there are rare. This may be due to large-magnitude earthquakes episodically triggering coseismic rapid landslides, which preferentially remove weak rock from the fault damage zone. Our analysis suggests that the necessary conditions for earthflow formation in central California include some combination of reduced rock strength, fine-grained sedimentary rock, threshold precipitation and relief, and possibly the absence of large-magnitude earthquakes. These conditions likely hold for earthflow development in other areas, and our work suggests that local variations in rock strength and seismicity, such as those associated with fault zones, need to be taken into account in order to accurately predict earthflow occurrence.

Item Type:Article
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URLURL TypeDescription
Scheingross, Joel S.0000-0002-7220-8084
Minchew, Brent M.0000-0002-5991-3926
Simons, Mark0000-0003-1412-6395
Lamb, Michael P.0000-0002-5701-0504
Additional Information:© 2013 Geological Society of America. Received 1 May 2012. Revision received 1 October 2012. Accepted 2 October 2012. Science editor: a. hope jahren Aassociate editor: shanaka de silva First published online January 11, 2013. We benefited from fruitful discussions with Jean- Philippe Avouac, Jean-Paul Ampuero, and Piyush Agram. Eric Fielding, Yang Zheng, and Brian Hawkins helped facilitate Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data access. The Keck Institute for Space Studies provided funding for this study through the Advanced Earth Surface Observation Project. Scheingross was partially supported by a National Science Foundation Graduate Research Fellowship. We thank three anonymous reviewers for insightful comments that improved the structure and clarity of this manuscript.
Group:Keck Institute for Space Studies
Funding AgencyGrant Number
Keck Institute for Space Studies (KISS)UNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Issue or Number:3-4
Record Number:CaltechAUTHORS:20130429-095854132
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Official Citation: Joel S. Scheingross, Brent M. Minchew, Benjamin H. Mackey, Mark Simons, Michael P. Lamb, and Scott Hensley Fault-zone controls on the spatial distribution of slow-moving landslides Geological Society of America Bulletin, March 2013, v. 125, no. 3-4, p. 473-489
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38150
Deposited By: Tony Diaz
Deposited On:15 May 2013 19:23
Last Modified:09 Nov 2021 23:33

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