Postseismic afterslip 30 years after the 1978 Tabas-e-Golshan (Iran) earthquake: observations and implications for the geological evolution of thrust belts

Copley, Alex (2014) Postseismic afterslip 30 years after the 1978 Tabas-e-Golshan (Iran) earthquake: observations and implications for the geological evolution of thrust belts. Geophysical Journal International, 197 (2). pp. 665-679. ISSN ISSN: 0956-540X, ESSN: 1365-246X DOI 10.1093/gji/ggu023

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Official URL: http://gji.oxfordjournals.org/content/197/2/665

Abstract

This paper presents InSAR observations of postseismic afterslip occurring up to 30 yr after the Mw7.3 1978 Tabas-e-Golshan thrust-faulting earthquake in eastern Iran. Comparison of the surface motion from 1996 to 1999 with that from 2003 to 2010, along with information provided by the Quaternary-averaged slip rates of faults in the region, suggests that the imaged slip is transient and decaying through time. Models of the surface deformation field imply slip on faults dipping at 55 ± 10°, reaching from the surface to depths of 4–5 km, and slipping at 5 ± 1 mm yr-1. These faults outcrop on the margins of low anticlinal hills composed of actively uplifting Neogene deposits. When compared with the previously studied main shock focal parameters (slip on a plane dipping at 16 ± 5° with a centroid depth of \~9 km), and the aftershock distribution (a band at \~6–14 km), the InSAR results imply postseismic slip on a high-angle thrust ramp connecting the surface anticlines to the coseismic low-angle fault plane at depth. In one location, both a thrust ramp and also a backthrust are postseismically active. The InSAR observations demonstrate the role of postseismic afterslip in the growth of these commonly observed thrust belt geometries, and highlight that deformation throughout the seismic cycle can contribute to the geological evolution of regions of active faultin

Item Type: Article
Additional Information: The SAR data were provided by the European Space Agency. This article has been accepted for publication in Geophysical Journal International © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society.All rights reserved.
Uncontrolled Keywords: 2014AREP; IA68;
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
07 - Gold Open Access
Journal or Publication Title: Geophysical Journal International
Volume: 197
Page Range: pp. 665-679
Identification Number: 10.1093/gji/ggu023
Depositing User: Sarah Humbert
Date Deposited: 25 Aug 2014 22:49
Last Modified: 30 Aug 2015 02:30
URI: http://eprints.esc.cam.ac.uk/id/eprint/3097

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