Paleoearthquake History Along the Southern Segment of the Daliangshan Fault Zone in the Southeastern Tibetan Plateau. Issue 7 (4th July 2019)

• Record Type: Journal Article
• Authors: Sun, Haoyue; He, Honglin; Ikeda, Yasutaka; Wei, Zhanyu; Chen, Changyun; Xu, Yueren; Shi, Feng; Bi, Lisi; Shirahama, Yoshiki; Okada, Shinsuke; Echigo, Tomoo
• Is Part Of: Tectonics. Volume 38:Issue 7(2019)
• Page Start: 2208
• Page End: 2231
• Publication Date: 2019-07-04
• Subjects: paleoearthquake -- Daliangshan fault zone -- southeastern Tibetan Plateau; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1029/2018TC005009
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: Assessing the seismic hazard of a fault is usually based on its record of strong earthquakes. Earthquake records with long periods of quiescence for active faults can lead to underestimates of seismic hazards, such as for the Longmenshan fault zone which produced the unanticipated 2008 M w 7.9 Wenchuan earthquake. The Daliangshan fault zone has a low slip rate and has not produced any strong earthquakes in history. As a result, little is known about its paleoearthquake history, including the behavior of any strong earthquakes it might produce and the seismic hazards posed by the Daliangshan fault zone. To solve this problem, we excavated four trenches across the Jiaojihe and Butuo faults along the southern segment of the Daliangshan fault zone. The paleoseismic investigations revealed six paleoearthquakes on the Jiaojihe fault in ~20, 000 years and determined another seven rupturing events on the Butuo fault in ~42, 000 years. The strong earthquake history of the Jiaojihe fault has evidence of temporal clustering, while the Butuo fault exhibits a relatively periodic recurrence pattern with intervals of 1, 710–2, 460 years. Based on its surface rupture length and the magnitude of observed displacement, the southern segment of the Daliangshan fault zone is capable of producing M > 6.5 earthquakes. Furthermore, based on their respective slip rates and the elapsed times since the most recent events along the Jiaojihe and Butuo faults, they have accumulated seismic energy equivalent to M ~ 7.6, suggesting they pose a significant seismic hazard to the southeastern Tibetan Plateau. Key Points: We develop a ~42, 000‐year paleoearthquake history of the southern segment of the Daliangshan fault zone The Jiaojihe and Butuo faults are capable of producing M > 6.5 earthquakes, and latest events were 1, 400 and 2, 400 years ago, respectively The southern segment of the Daliangshan fault zone poses a high seismic hazard for its region