摘要
通过对色尔腾山山前断裂带乌加河段断层地貌研究,并结合前人对断裂带断裂活动性的工作,分析得到乌加河活动断裂段晚更新世晚期(距今1.445～2.234万年)以来平均垂直位移速率是0.48～0.75 mm/a,全新世早中期以来(距今5 570～8 830年)平均垂直位移速率是0.56～ 0.88 mm/a.利用5个探槽中揭露的古地震现象,结合前人对该断裂带古地震的研究结果,分析确定出2.7万年以来,色尔腾山山前断裂乌加河段共揭露出5次古地震事件,重复间隔约为4 300～4 400年.距今8 000～9 000年之间可能为一个古地震丛,而距今1～2万年之间可能遗漏了两次古地震事件.对比断层陡坎的高度与探槽中揭示出古地震事件的位移和,以及由断层平均位移速率和一次事件的位移得到古地震的重复间隔,得到阿拉盖兔探槽中缺失了3次古地震事件,整个活动断裂段上可能缺失了两次古地震事件.
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 (14.45～22.34 ka BP) and 0.56～0.88 mm/a since the early-middle Holocene (5.57～8.83 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 4.3～4.4 ka. A cluster of paleoearthquakes occurred probably during 8～9 ka BP and two paleoseismic events in 10～20 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 dislocation 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.
出处
《地震学报》
CSCD
北大核心
2003年第1期62-71,共10页
Acta Seismologica Sinica
基金
国家重大基础研究发展规划项目<大陆强震机理与预测>(G199804070)
地震科学联合基金(100068)共同资助.
