Spatial variations in fault friction related to lithology from rupture and afterslip of the 2014 South Napa, California, earthquake

Michael Floyd; Richard Walters; John Elliot; Gareth J. Funning; Jerry L. Svarc; Jessica R. Murray; Andy Hooper; Yngvar Larsen; Petar Marinkovic; Roland Bürgmann; Ingrid A. Johanson; Tim Wright

doi:10.1002/2016GL069428

Spatial variations in fault friction related to lithology from rupture and afterslip of the 2014 South Napa, California, earthquake

Geophysical Research Letters

By: Michael Floyd, Richard Walters, John Elliot, Gareth J. Funning, Jerry L. Svarc, Jessica R. Murray, Andy Hooper, Yngvar Larsen, Petar Marinkovic, Roland Bürgmann, Ingrid A. Johanson, and Tim Wright

https://doi.org/10.1002/2016GL069428

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Abstract

Following earthquakes, faults are often observed to continue slipping aseismically. It has been proposed that this afterslip occurs on parts of the fault with rate-strengthening friction that are stressed by the mainshock, but our understanding has been limited by a lack of immediate, high-resolution observations. Here we show that the behavior of afterslip following the 2014 South Napa earthquake varied over distances of only a few kilometers. This variability cannot be explained by coseismic stress changes alone. We present daily positions from continuous and survey GPS sites that we re-measured within 12 hours of the mainshock, and surface displacements from the new Sentinel-1 radar mission. This unique geodetic data set constrains the distribution and evolution of coseismic and postseismic fault slip with exceptional resolution in space and time. We suggest that the observed heterogeneity in behavior is caused by lithological controls on the frictional properties of the fault plane.

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Additional publication details
Publication type	Article
Publication Subtype	Journal Article
Title	Spatial variations in fault friction related to lithology from rupture and afterslip of the 2014 South Napa, California, earthquake
Series title	Geophysical Research Letters
DOI	10.1002/2016GL069428
Volume	43
Issue	13
Year Published	2016
Language	English
Publisher	American Geophysical Union
Contributing office(s)	Earthquake Science Center
Description	9 p.
First page	6808
Last page	6816
Country	United States
State	California
City	San Francisco
Other Geospatial	South Napa
Online Only (Y/N)	N
Additional Online Files (Y/N)	N
Google Analytic Metrics	Metrics page