Abstract: The three-dimensional structure of the ground fissure zone in the area of Datong Railway Bureau is studied in detail form the data of field investigation, geological trenching and shallow seismic prospecting, as well as analyis of its neotectonic background and underground water overextraction. The developing ground fissure zone has been propagating westwards at a rate of 260 ～ 520 m/a since 1983; Its differential movement rate across the zone reaches 22.1～24.4mm/a. The extensional rate of the main fissure is 1.11～11.6mm/a, vertical slip rate about 0.2～8.57mm/a, and left-lateral slip rate about 1.87～3.57mm/a. Its active behavior belongs to a brittle-plastic model. This ground fissure zone has been caused by the recent creep along the Baimacheng fault-aburied active fault. The local overextraction of the underground water has accelerated the development of the ground fissure zone. The formation of the ground fissures is an aseismic geologic hazard.

Key words: Shanxi Provence, Ground fissure, Slip rate, Geologic hazard

摘要： 通过实地考察、槽探和浅层地震探测等手段以及对地质构造和地下水超采环境的分析,详细地研究了大同铁路分局地裂缝带的三维构造特征,指出现今处于发展中的地裂缝带是由东向西扩展的,扩展速率为260～520m/a,地裂缝带两侧的差异升降运动速率达22.1～24.4mm/a,主地裂缝带的水平拉张速率约1.11～11.6mm/a,垂直错动速率0.2～8.57mm/a,左旋错动速率1.87～3.57mm/a.地裂缝带的活动方式为无震蠕滑型,扩展中的地裂缝是一种无震的地质灾害。

关键词: 山西, 地裂缝, 活动速率, 地质灾害