The Locking Depth of the Cholame Section of the San Andreas Fault from ERS2-Envisat InSAR

Guillaume Bacques,Marcello De Michele,Hideo Aochi,Daniel Raucoules

doi:10.3390/rs10081244

Guillaume Bacques, Marcello De Michele + Show 2 more

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https://doi.org/10.3390/rs10081244

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Abstract

The Cholame section of the San Andreas Fault (SAF), which has been considered locked since 1857, has been little studied using geodetic methods. In this study, we propose to use Interferometric Synthetic Aperture Radar (InSAR) to contribute to the improvement of the knowledge of this section of the SAF. In particular, the objective of this work is to provide a description of the transition between the Parkfield and Cholame-Carrizo segments further southeast by producing an estimate of the locking depth of the Cholame segment by combining ERS2 (European Remote Sensing) and Envisat Advanced SAR (ASAR) satellites data. Our results indicate that the locking depth between the Parkfield and the Cholame-Carrizo segments deepens to the southeast. We then use these results as a hint to refine the tectonic loading on this section of the SAF.

Highlights

The Pacific Plate moves relative to the North American Plate at 3.5 cm/year
From the stack of interferograms (Figure 2), we notice that the transition between the Parkfield section and the Cholame section of the San Andreas Fault (SAF) is very marked, reflecting a behavioural difference between these two sections, after the 2004 Mw6 Parkfield earthquake
From the combination of ERS2 and Envisat Synthetic Aperture Radar (SAR) interferograms, we obtain a set of ground velocity profiles at a high spatial resolution

Summary

Introduction

The Pacific Plate moves relative to the North American Plate at 3.5 cm/year This displacement is partly accommodated at the borders of the two plates by strong earthquakes, partly through aseismic creep. The San Andreas Fault (SAF) is locked for most of its length, except for its central part in continuous slip, e.g. Titus et al [1]. It is responsible for strong earthquakes, some of which have marked the history of the United States of America (Fort Tejon 1857, San Francisco 1906, Long Beach 1933, County Kern 1952, Loma Prieta 1989). The Cholame-Carrizo section is positioned about 20 km southeast of the 2004 Parkfield earthquake epicenter (Figure 1)

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