Deep structure beneath the southwestern section of the Longmenshan fault zone and seimogenetic context of the 4.20 Lushan MS7.0 earthquakeReport as inadecuate




Deep structure beneath the southwestern section of the Longmenshan fault zone and seimogenetic context of the 4.20 Lushan MS7.0 earthquake - Download this document for free, or read online. Document in PDF available to download.

Chinese Science Bulletin

, Volume 58, Issue 28–29, pp 3467–3474

First Online: 14 August 2013Received: 09 June 2013Accepted: 05 July 2013DOI: 10.1007-s11434-013-6013-x

Cite this article as: Zhan, Y., Zhao, G., Unsworth, M. et al. Chin. Sci. Bull. 2013 58: 3467. doi:10.1007-s11434-013-6013-x

Abstract

Magnetotelluric measurements were carried out along two profiles across the middle and southwestern sections of the Longmenshan fault zone LMSf from 2009 to 2011, after the 2008 Wenchuan MW7.9 earthquake. The former profile crosses the Wenchuan event epicenter and the latter one crosses 2013 Lushan MS7.0 event epicenter. The data were analyzed using advanced processing techniques, including phase tensor and two-dimensional inversion methods, in order to obtain reliable 2-D profiles of the electrical structure in the vicinity of the two earthquakes. A comparison of the two profiles indicates both similarities and differences in the deep crustal structure of the LMSf. West of the southwestern section, a crustal high conductivity layer HCL is present at about 10 km depth below the Songpan-Garzê block; this is about 10 km shallower than that under the middle section of the LMSf. A high resistivity body HRB is observed beneath the southwestern section, extending from the near surface to the top of upper mantle. It has a smaller size than the HRB observed below the middle section. In the middle section, there is a local area of decreased resistivity within the HRB but there is absence of this area. The 2013 Lushan earthquake occurred close to the eastern boundary of HRB and the Shuangshi-Dachuan fault, of which the seismogenic context has both common and different features in comparison with the 2008 Wenchuan event. On a large scale, the 2013 Lushan earthquake is associated with the HCL and deformation in the crust including HCL of the eastern Tibetan Plateau. In order to assess seismic risk, it is important to consider both the stress state and the detailed crustal structure in different parts of the LMSf.

KeywordsLongmenshan fault Lushan earthquake deep structure seismogenetic context This article is published with open access at Springerlink.com

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Author: Yan Zhan - GuoZe Zhao - Martyn Unsworth - LiFeng Wang - XiaoBin Chen - Tao Li - QiBin Xiao - JiJun Wang - Ji Tang - JunTa

Source: https://link.springer.com/







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