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Paleoearthquake History Along the Southern Segment of the Daliangshan Fault Zone in the Southeastern Tibetan Plateau
Author(s) -
Sun Haoyue,
He Honglin,
Ikeda Yasutaka,
Wei Zhanyu,
Chen Changyun,
Xu Yueren,
Shi Feng,
Bi Lisi,
Shirahama Yoshiki,
Okada Shinsuke,
Echigo Tomoo
Publication year - 2019
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2018tc005009
Subject(s) - seismology , geology , seismic gap , seismic hazard , fault (geology) , plateau (mathematics) , elastic rebound theory , active fault , slip (aerodynamics) , paleoseismology , mathematical analysis , physics , mathematics , thermodynamics
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.