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The Seismogenic Structure and Deformation Mechanism of the Lushan ( M w 6.6) Earthquake, Sichuan, China
Author(s) -
Rongjun ZHOU,
Yong LI,
Chongjian SHAO,
Jinrong SU,
Zhaokun YAN,
Liang YAN
Publication year - 2016
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12686
Subject(s) - seismology , aftershock , geology , fault (geology) , peak ground acceleration , foreshock , focal mechanism , hypocenter , magnitude (astronomy) , deformation (meteorology) , active fault , earthquake location , earthquake rupture , geodesy , induced seismicity , ground motion , oceanography , physics , astronomy
Abstract On April 20th, 2013, an earthquake of magnitude M w 6.6 occurred at Lushan of Sichuan on the southern segment of the Longmenshan fault zone, with no typical coseismic surface rupture. This work plotted an isoseismal map of the earthquake after repositioning over 400 post–earthquake macro‐damage survey points from peak ground acceleration (PGA) data recorded by the Sichuan Digital Strong Earthquake Network. This map indicates that the Lushan earthquake has a damage intensity of IX on the Liedu scale, and that the meizoseismal area displays an oblate ellipsoid shape, with its longitudinal axis in the NE direction. No obvious directivity was detected. Furthermore, the repositioning results of 3323 early aftershocks, seismic reflection profiles and focal mechanism solutions suggests that the major seismogenic structure of the earthquake was the Dayi Fault, which partly defines the eastern Mengshan Mountain. This earthquake resulted from the thrusting of the Dayi Fault, and caused shortening of the southern segment of the Longmenshan in the NW–SE direction. Coseismal rupture was also produced in the deep of the Xinkaidian Fault Based on the above seismogenic model and the presentation of coseismic surface deformation, it is speculated that there is a risk of more major earthquakes occurring in this region.