The Holocene paleoseismicity of the North Zhongtiaoshan Faults in Shanxi Province, China

摘要

The late Pleistocene and Holocene sediment along the North Zhongtiaoshan Faults (NZF) in Shanxi Province north China provided excellent records of events and displacing rate of the Holocene paleoearthquakes.We conducted a paleoseismological studywith the geomorphologicalmapping and trenching along the 137-km normal faults trending NE-NEE. Identified from the results of trenching along the NZF, the first rupturing event in the Holocene was between 10,420 ± 145 and 11,245 ± 55 Cal a BP, the second event was between 7860 ± 80 and 8100 ± 90 Cal a BP, the third event was between 4540 ± 110 and 4695 ± 125 Cal a BP and the fourth event was between 465 ± 45 and 675 ± 45 Cal a BP. The average interval of the four events interpreted was 3370 yr. The trending of the vertical displacements of four events and of the estimated magnitudes of the paleoearthquakes shows a decelerating faulting pattern of the NZF in the Holocene. The paleoseismic events went stronger from the northeast segment to the southwest segment along the NZF and themost active faulting around 465 ± 45 Cal a BP was in the Hanyang Segment.