山区孕灾环境下地震和极端天气气候对地质灾害的影响

Compound effects of earthquakes and extreme weathers on geo-hazards in mountains

开展多致灾因子耦合作用下的地质灾害研究对山区综合风险防范和可持续发展至关重要。在山区孕灾环境中,极端降水和地震是触发滑坡等地质灾害的主要因素。以往研究多在山地孕灾环境稳定的假设下,研究极端降水或强震单独导致的地质灾害过程,而对孕灾环境变化下的极端天气和地震致灾因子共同诱发地质灾害的关注不足。针对这一问题,梳理了国内外发生在山区的地震和极端降水共同导致滑坡等地质灾害的研究案例,系统总结了山区强震与极端降水引发滑坡等地质灾害的相互作用过程。现有研究已在地震和极端降水引发滑坡等地质灾害的问题上取得了以下认识:(1)山区地震可强烈改变孕灾环境,显著提升震后降水引发地质灾害的可能性,放大极端降水-滑坡灾害链;(2)地震对降水引发滑坡的影响随着震后时间的推移逐渐减弱,该现象可能受控于气候因素;(3)在全球气候变化背景下,极端天气气候事件增多,定量研究山区强震和极端天气气候二者“遭遇”下的地质灾害链将面临更多挑战。由于观测案例不足,针对山区地震与极端降水共同导致地质灾害的研究仍缺少定量分析,触发机理也需进一步明确。

Studying interplays among different geo-hazard triggers is crucial for mitigating integrated hazard risks and sustaining sustainability in mountain communities.Extreme precipitation and strong seismicity in mountain environment are major triggers for initiation of geo-hazards,such as landslides.Traditional studies on geo-hazards have been extensively carried out by treating them with single triggers,yet compound effects of earthquakes and extreme weathers on geo-hazards initiations have largely been ignored.Regional-scale geo-hazard cases that were jointly caused by earthquake and extreme weather have been reviewed to analyze the interplay between both triggers in initiating geo-hazards.Three major points can be drawn from existing literatures:1)strong mountain earthquakes can alter mountain environments,which could significantly increase the likelihood of geo-hazards’initiations and magnify its magnitude;2)this magnifying effect decays with time and may be controlled by climate;3)extreme weathers have been increasing under climate change and its coalition with strong earthquakes in tectonic mountains will lead to more complicated problems.Due to a lack of observations,joint triggering mechanism of extreme weathers and earthquakes on geo-hazard initiation remains elusive.