汶川震区震后地质灾害发育分布及演化特征统计分析

Geological Hazards after Earthquake in Wenchuan Earthquake Area:Distribution and Evolvement Features

汶川地震是21世纪以来中国发生震级最大的地震。为了分析汶川震区震后地质灾害发育分布,根据三大数据库及新闻稿的数据,以滑坡和泥石流为例,从规模、烈度及时间3个方面对汶川震后9a来地质灾害演化特征及差异性进行了初步统计分析,并预测了2018—2025年滑坡和泥石流的演化趋势。结果表明:①滑坡数量与规模呈反比,与烈度也呈反比,且滑坡主要集中在7—9月份;②泥石流规模特征较均匀,高烈度区泥石流数量大于低烈度区,且主要集中在7—9月份;③滑坡在震后初期数量较少,泥石流则在震后初期数量较多;④初步分析汶川震后滑坡和泥石流演化特征差异的原因是这2种灾害的产生条件不同;⑤预测滑坡在短期内呈震荡式衰减趋势,高峰周期为3~5a,泥石流呈水平波动趋势,高峰周期为3~5a。

Wenchuan earthquake is the largest earthquake in China since the 21st century.From the aspects of scale,intensity and time,we made a preliminary statistical analysis on the characteristics and differences of geological disasters(landslide and debris flow in this paper)evolved nine years after the Wenchuan earthquake,and predicted the evolution trend of landslide and debris flow during 2018-2025.Results demonstrated that:(1)The number of landslide is inversely proportional to the scale and intensity of earthquake,and landslides mainly happened in July-September.(2)The scale of debris flow is more uniform,and the number of debris flow is approximately proportional to the intensity of earthquake,and debris flow mainly concentrated in July-September.(3)In the early stage after the earthquake,landslide was small in number while debris flow was large.(4)The difference in the evolvement characteristics between landslide and debris flow after the Wenchuan earthquake lies in the formation conditions.(5)According to prediction,landslide will decrease in an oscillating manner in a short period of time,with a cycle of 3-5 years,whereas debris flow will fluctuate horizontally,also with a cycle of 3-5 years.