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Seismotectonics of the 2017-2018 Songyuan earthquake sequence, northeastern China; passive bookshelf faulting and block rotation in the Songliao Basin

Su Zhe, Xu Xiwei, Liang Shanshan and Wang Erchie
Seismotectonics of the 2017-2018 Songyuan earthquake sequence, northeastern China; passive bookshelf faulting and block rotation in the Songliao Basin
Seismological Research Letters (March 2020) 91 (3): 1593-1605

Abstract

The high frequency of earthquake clusters generated by pure strike-slip faulting over the past 3 yr (beginning in 2017 in the Songliao basin, northeastern China) has motivated us to consider why lateral strike slip and not extension determines the seismic activity within the Songliao basin. Precise location and characterization of relocated aftershocks, forward modeling of the coseismic displacement field, and Global Positioning System (GPS) monitoring data are combined to detect the possible seismogenic structures of the Songyuan earthquake sequence. The 2017 ML 5.3 aftershock cluster coincided with the northeast-striking Fuyu-Zhaodong fault (FZF), and the 2018 aftershock swarm followed the linear trend (N42 degrees W) of the Songhuajiang fault (SHF). In addition, the forward modeling results indicate that during the earthquakes, right-lateral and left-lateral strike-slip displacements occurred simultaneously along the FZF and SHF, respectively. These two strike-slip faults joined to accommodate the intervening crustal blocks' asymmetrical east-west convergence and a single northward extrusion. We also utilize 5 yr of GPS data to construct the regional strain-rate map for the basin. The measurements show that right-lateral transform motion along the immense northeast-striking right-lateral strike-slip faults, for example, the Tanlu fault zone and the FZF, impose a northeast-striking simple shear across the Songliao basin. This simple shear not only caused left-lateral movement on the minor northwest-striking left-lateral strike-slip faults such as the SHF but also rotated them approximately 14 degrees clockwise into their present orientations. The results of the proposed bookshelf faulting model in which the predominant northeast-striking parallel faults are initiated are consistent with the observed lineament orientations, focal mechanisms, and earthquake distributions. The sharp shift in the subduction direction of the Pacific plate seems to have had a considerable influence on the intracontinental deformation in China, at least throughout northeastern China.


ISSN: 0895-0695
EISSN: 1938-2057
Serial Title: Seismological Research Letters
Serial Volume: 91
Serial Issue: 3
Title: Seismotectonics of the 2017-2018 Songyuan earthquake sequence, northeastern China; passive bookshelf faulting and block rotation in the Songliao Basin
Affiliation: China Earthquake Administration, Laboratory of Crustal Dynamics, Beijing, China
Pages: 1593-1605
Published: 20200311
Text Language: English
Publisher: Seismological Society of America, El Cerrito, CA, United States
References: 90
Accession Number: 2020-034452
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch maps
N42°30'00" - N47°30'00", E122°00'00" - E127°00'00"
Secondary Affiliation: China Earthquake Networks Center, CHN, ChinaChinese Academy of Sciences, Institute of Geology and Geophysics, CHN, China
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202022
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