香港地区晚更新世的构造活动性

The Late Pleistocene Tectonic Activity in Hong Kong

河沥背西北走向的断层最近期的构造活动发生于晚更新世时期,至全新世已经完全停止。晚更新世后期香港地区(如河沥背、黄竹洋、南山和贝澳)滑坡、泥石流和巨型滚石等重力地质事件频繁发生,而且还有原地重复的情况。按照地面地质破坏现象的分布范围、规模和数量等指针综合分析,在晚更新世后期香港地区可能曾经遭受过强烈地震的袭击,其烈度估计可达IX-X度,而且在数万年之内曾经多次发生。1万年以来,构造运动减弱,地震活动降低,地面运动的最大强度相应减小。

The most recent tectonic movement of the NW-trending fault at the Ho Lek Pui area was likely to have occurred during the late Pleistocene. The fault activity have ceased in the Holocene. Possible signs of mass wasting processes, including landslides, debris flows and displacement of very large boulders in the late Pleistocene have been identified in different parts of Hong Kong, such as the Ho Lek Pui, Wong Chuk Yeung, Nam Shan and Pui 0 areas. Some of the landslide debris lobes were found to be the products of multiple slope failures. Based on an integrated analysis of the distribution, scale and quantity of the potential evidence for neotectonic movement, it is suggested that Hong Kong may have been affected by intensive seismic shaking clustered within tens of thousands of years in the late Pleistocene, with intensity values of possibly between IX and X. It is found that in the recent 10 000 years, the tectonic activity and seismicity in the region have diminished, so that the intensity of ground motion has been reduced correspondingly.