Geomorphic study on Wujiahe segment of Serteng piedmont fault, Inner Mongolia is made. Through analysis of the available data in combination with the results of predecessors studies it can be obtained that average ver...Geomorphic study on Wujiahe segment of Serteng piedmont fault, Inner Mongolia is made. Through analysis of the available data in combination with the results of predecessors studies it can be obtained that average vertical displacement rate is 0.48~0.75 mm/a along the Wujiahe segment since the late Pleistocene (14.450~22.340 ka BP) and 0.56~0.88 mm/a since the early-middle Holocene (5.570~8.830 ka BP). Analyzing paleoseismic phenomena revealed in the excavated 5 trenches in combination with the results of predecessors studies of paleoearthquakes on the fault, we determine five paleoseismic events on the Wujiahe segment of Serteng piedmont fault since 27.0 ka BP and the recurrence interval to be about 4.300~4.400 ka. A cluster of paleoearthquakes occurred probably during 8.000~9.000 ka BP and two paleoseismic events in 10.000~20.000 ka BP may be missed. A comparison between height of fault scarps and sum of displacement caused by paleoseismic events revealed in trenches, and recurrence interval of paleoseismic events obtained from average displacement rate along the fault and the disloca-tion by one event suggest that three paleoseismic events are absent in Alagaitu trench. Two paleoseismic events may be absent on the whole active fault segment.展开更多
Based on remote sensing data, field investigation and trench measurement along the piedmont fault (Wujumengkou Dongfengcun) of Mt. Serteng, the vertical displacement rate has been found to be 0 88～1 83mm/a since the ...Based on remote sensing data, field investigation and trench measurement along the piedmont fault (Wujumengkou Dongfengcun) of Mt. Serteng, the vertical displacement rate has been found to be 0 88～1 83mm/a since the late period of late Pleistocene and 0 89mm/a since the middle period of Holocene. Using the progressive constraining method,five paleoearthquake events have been distinguished from two large trenches since Holocene. They occurred 9000±1300a B.P., 6500±500a B.P., 5770a B.P., 4200±300a B.P. and 3250±250a B.P., respectively. From the late period of late Pleistocene to the beginning of Holocene, some paleoearthquake events may have been missed due to a variety of reasons. All of the paleoearthquake events displayed clustering characteristics to a certain extent. The first cluster was occurred around 8900a B.P., the second cluster occurred between 5700～6500a B.P. and the last cluster was occurred in 3250～4200 a B.P. The interval between the first cluster and the second cluster was about 2400a while that between the second cluster and the third cluster was only 1570a. No earthquake events have cut the ground surface along this active fault segment since 3250a B.P. The lapse time is more than the recurrence interval between two paleoearthquake clusters. Therefore, there is a potential risk for a recurring earthquake along this active fault segment.展开更多
基金State Key Basic Research Development and Programming Project Mechanism and Prediction of Continental Strong Earthquakes (G199804070) and Joint Earthquake Science Foundation of China (100068).
文摘Geomorphic study on Wujiahe segment of Serteng piedmont fault, Inner Mongolia is made. Through analysis of the available data in combination with the results of predecessors studies it can be obtained that average vertical displacement rate is 0.48~0.75 mm/a along the Wujiahe segment since the late Pleistocene (14.450~22.340 ka BP) and 0.56~0.88 mm/a since the early-middle Holocene (5.570~8.830 ka BP). Analyzing paleoseismic phenomena revealed in the excavated 5 trenches in combination with the results of predecessors studies of paleoearthquakes on the fault, we determine five paleoseismic events on the Wujiahe segment of Serteng piedmont fault since 27.0 ka BP and the recurrence interval to be about 4.300~4.400 ka. A cluster of paleoearthquakes occurred probably during 8.000~9.000 ka BP and two paleoseismic events in 10.000~20.000 ka BP may be missed. A comparison between height of fault scarps and sum of displacement caused by paleoseismic events revealed in trenches, and recurrence interval of paleoseismic events obtained from average displacement rate along the fault and the disloca-tion by one event suggest that three paleoseismic events are absent in Alagaitu trench. Two paleoseismic events may be absent on the whole active fault segment.
文摘Based on remote sensing data, field investigation and trench measurement along the piedmont fault (Wujumengkou Dongfengcun) of Mt. Serteng, the vertical displacement rate has been found to be 0 88～1 83mm/a since the late period of late Pleistocene and 0 89mm/a since the middle period of Holocene. Using the progressive constraining method,five paleoearthquake events have been distinguished from two large trenches since Holocene. They occurred 9000±1300a B.P., 6500±500a B.P., 5770a B.P., 4200±300a B.P. and 3250±250a B.P., respectively. From the late period of late Pleistocene to the beginning of Holocene, some paleoearthquake events may have been missed due to a variety of reasons. All of the paleoearthquake events displayed clustering characteristics to a certain extent. The first cluster was occurred around 8900a B.P., the second cluster occurred between 5700～6500a B.P. and the last cluster was occurred in 3250～4200 a B.P. The interval between the first cluster and the second cluster was about 2400a while that between the second cluster and the third cluster was only 1570a. No earthquake events have cut the ground surface along this active fault segment since 3250a B.P. The lapse time is more than the recurrence interval between two paleoearthquake clusters. Therefore, there is a potential risk for a recurring earthquake along this active fault segment.
