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A blind thrust and overlying folding earthquake of the 2016 M (sub w) 6.0 Hutubi earthquake in northern Tien Shan fold-and-thrust belts, China

Yang Yinghui, Jyr-Ching Hu, Chen Qiang, Wang Zegen and Min-Chien Tsai
A blind thrust and overlying folding earthquake of the 2016 M (sub w) 6.0 Hutubi earthquake in northern Tien Shan fold-and-thrust belts, China
Bulletin of the Seismological Society of America (January 2019) 109 (2): 770-779

Abstract

The 2016 M (sub w) 6.0 Hutubi earthquake occurred in the northern Tien Shan fold-and-thrust belts, China. However, the coseismic fault rupture model and the seismotectonics of the 2016 Hutubi earthquake remain uncertain up to the present due to the small magnitude, deep hypocenter, and no surface rupture caused by the seismogenic fault. Here, we show the evidence that the 2016 Hutubi earthquake occurred on a deep (15-20km) blind-thrust fault, and the rupture of the blind fault triggers the slip of a shallow overlying fold. Ascending and descending Interferometric Synthetic Aperture Radar (InSAR) observations captured by Sentinel-1A/1B satellites are used to construct the seismogenic structure of the 2016 Hutubi earthquake. It is found that a single fault fails to provide a good fit to the observed Sentinel-1 ascending and descending InSAR deformation. A shallow fault-bend fold with strike along the surface trace of the Qigu Anticline and a varying dip angle along the down-dip direction is proposed in this study based on the geodetic observations, which significantly improves the model fit to the InSAR observations. The estimated faulting model shows that the 2016 Hutubi earthquake occurred on a deep blind fault with 264.4 strike and 28.8 dip, and significant fault slip is located at the depth of 13-18km with a peak slip of approximately 10.0cm. The triggered shallow fault-bend fold has a listric surface with slight predominant thrust slip. The static Coulomb stress change from the mainshock on the shallow fold structure is negative, which indicates the dynamic stress may play a more important role than the static stress in the triggering of the shallow fault-bend fold in this case. The result of this study suggests that a moderate earthquake with a deep hypocenter has the potential to trigger the rupture of the shallow overlying fault-bend fold in this zone.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 109
Serial Issue: 2
Title: A blind thrust and overlying folding earthquake of the 2016 M (sub w) 6.0 Hutubi earthquake in northern Tien Shan fold-and-thrust belts, China
Affiliation: Southwest Petroleum University, Department of Remote Sensing and Surveying Engineering, Chengdu, China
Pages: 770-779
Published: 20190129
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 40
Accession Number: 2019-014758
Categories: Structural geologySeismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., sketch maps
N43°00'00" - N46°00'00", E84°00'00" - E88°00'00"
Secondary Affiliation: National Taiwan University, TWN, TaiwanSouthwest Jiaotong University, CHN, ChinaCentral Weather Bureau, TWN, Taiwan
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201910
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