The 2013 Mw 6.2 Khaki‐Shonbe (Iran) Earthquake: Insights into seismic and aseismic shortening of the Zagros sedimentary cover

Earth and Space Science

J. R. Elliott⁷  E. A. Bergman²  A. C. Copley¹  A. R. Ghods⁵  E. K. Nissen⁶  B. Oveisi³  M. Tatar⁸  R. J. Walters⁴ 

[1] COMET+, Department of Earth Sciences, Bullard Laboratories, Cambridge, UK;Center for Imaging the Earth's Interior, Department of Physics, University of Colorado Boulder, Boulder, Colorado, USA;Seismotectonics Department, Geological Survey of Iran, Tehran, Iran;COMET+, School of Earth and Environment, University of Leeds, Leeds, UK;Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences, Zanjan, Iran;Department of Geophysics, Colorado School of Mines, Golden, Colorado, USA;COMET+, Department of Earth Sciences, University of Oxford, Oxford, UK;International Institute of Earthquake Engineering and Seismology, Tehran, Iran

关键词: earthquake;    faulting;    folding;    insar;    aftershocks;    shortening;   

DOI  :  10.1002/2015EA000098

来源: Wiley

【 摘 要 】

Abstract

Determining the relationship between folding and faulting in fold and thrust belts is important for understanding the growth of geological structures, the depth extent of seismic slip, and consequently, the potential earthquake hazard. The 2013 M_w 6.2 Khaki-Shonbe earthquake occurred in the Simply Folded Belt of the Zagros Mountains, Iran. We combine seismological solutions, aftershock relocations, satellite interferometry, and field observations to determine fault geometry and its relationship with the structure, stratigraphy, and tectonics of the central Zagros. We find reverse slip on two along-strike, southwest dipping fault segments. The main shock rupture initiated at the lower northern end of the larger northwest segment. Based upon the hypocenter and rupture duration, slip on the smaller southern segment is likely aseismic. Both faults verge away from the foreland, toward the high-range interior, contrary to the fault geometries depicted in many structural cross sections of the Zagros. The modeled slip occurred over two mutually exclusive depth ranges above 10 km, resulting in long (∼16 km), narrow rupture segments (∼7 km). Aftershocks cluster in the depth range 3–14 km. This indicates reverse slip and coseismic shortening occurred mostly or exclusively in the sedimentary cover, with slip distributions likely to be lithologically controlled in depth by the Hormuz salt at the base of the sedimentary cover (∼10–12 km), and the Kazhdumi Formation mudrocks at upper levels (∼4–5 km). Our findings suggest lithology plays a significant role in the depth extent of slip found in reverse faults in folded belts, providing an important control on the potential size of earthquakes.

【 授权许可】

CC BY   
©2015. The Authors.

Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.