Classification and Semiquantitative Evaluation of Paleoearthquake Identification From Trenches on Normal Faults: A Case Study of Holocene Paleoearthquake Events From the Northern Margin of the Hetao Basin, China. Issue 1 (30th December 2022)

• Record Type: Journal Article
• Authors: Xu, Dongsheng; He, Zhongtai; Ma, Baoqi; Liang, Kuan; Long, Jianyu; Zhang, Hao
• Is Part Of: Tectonics. Volume 42:Issue 1(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-12-30
• Subjects: normal fault -- paleoearthquake -- trench -- semiquantitative evaluation -- Hetao basin; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1029/2022TC007443
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: Long paleoearthquake series are crucial for understanding the recurrence patterns of active faults and evaluating the seismic hazards of faults. In this study, the first semiquantitative evaluation of paleoearthquake events from trenches was applied to normal faults, and classification criteria for identifying paleoearthquakes in trenches on normal faults are proposed to demonstrate the feasibility of semiquantitative evaluations of paleoearthquake events on normal faults. In this study, 72 paleoearthquake trench sites on normal faults around the world were analyzed, and the main indicators for identifying paleoearthquakes on normal faults include the presence of vertical offset (VO), collapse wedge (CW), fissure (FIS), buried paleosol (BP), angular unconformity (AU), upward termination (UT), and sand liquefaction (LF) features. To describe and apply this semiquantitative evaluation method for paleoearthquake events on normal faults, 33 trenches for paleoearthquakes on a fault system in the northern margin of the Hetao Basin were comprehensively analyzed to determine Holocene paleoearthquake events on the Sertengshan, Wulashan, and Daqingshan piedmont faults, and the reliability of paleoearthquake events is discussed. The integrity of the paleoearthquake events obtained was tested by the displacement limit method. The Holocene paleoearthquake recurrence on the three faults was quasiperiodic; the coefficients of variation (COVs) were 0.44, 0.58, and 0.4. Plain Language Summary: In this study, 72 paleoearthquake trench sites on normal faults around the world are analyzed, and summarized the main indicators for identifying paleoearthquakes on normal faults. Classification criteria for identifying paleoearthquakes in trenches on normal faults are proposed. Using the faults of the northern margin of the Hetao Basin as an example, this study described a semiquantitative evaluation method for normal fault paleoearthquake events, and discussed the reliability of paleoearthquake events. The integrity of the paleoearthquake events obtained was tested by the displacement limit method. Combining with studies on the reliability and integrity of paleoearthquake events, we argue that it is feasible to apply semiquantitative evaluations of paleoearthquake events from trenches to paleoearthquake research on normal faults. Key Points: Semiquantitative evaluation of paleoearthquake identification from trenches to normal faults is applied for the first time Classification criteria are proposed for identifying paleoearthquakes in trenches on normal faults This study demonstrates the feasibility of semiquantitative evaluation of paleoearthquake events on normal faults