基于钻探的马袅-铺前断裂西段活动性探讨

Activity Discussion of the Western Segment of the Maniaopuqian Fault Revealed by Drilling

采用地球物理勘探和钻孔联合剖面探测相结合的方法,在海口市疏港公路沿线展开探测,通过分析断层的上断点、断错地层序列和盖层年龄,获得了马袅-铺前断裂西段的活动特征。钻探结果显示:马袅-铺前断裂西段为北倾正断层,最新活动时代推测为中更新世。该断裂段累计垂直位移量约为5 m,根据地层年代结果,初步估算出该段的垂直位移速率约为0.006±0.002 mm/a,说明断裂中更新世以来活动相对较弱。研究结果对正确评价海口市地震危险性,服务于经济建设和防震减灾规划具有重要现实意义。

In this paper combining with, geophysical exploration and composite drilling section exploration,respectively along Shugang road at Wenjia villiage, and activity characteristics of the western segment of the Maniao-puqian fault are obtained through the analysis of the depth of upper breaking point, faulted strata sequence and stratigraphic age. The composite drilling section reveals that the fault is a normal, inactive fault with north dipping, and its latest active age is the middle Pleistocene. The cumulative vertical displacement of the fault section is about 5 m revealed by drilling. According to the result of the stratigraphic age, it is preliminarily estimated that the vertical displacement rate of the segment is about 0.006±0.002 mm/a, indicating that the activity of the fault is relatively weak since Pleistocene. The research results have important practical significance for correctly evaluating Haikou earthquake risk and serving for economic construction and earthquake disaster prevention.