基于时序遥感数据的九寨沟核心景区崩塌发育分布特征

Development and Distribution Characteristics of Jiuzhaigou Collapse Based on Time Series Remote Sensing Data

2017年“8·8”地震导致九寨沟核心景区发育数以千计的高位或极高位崩塌灾害,造成自然景观及旅游设施严重损毁,且震后三年来仍呈现较高活动性。为降低崩塌对震后重建与生态修复带来的威胁,基于地震前后5期高精度遥感数据,通过多年实地调查、遥感解译与核密度分析等方法,从时间和空间角度分析了崩塌的空间聚集趋势及发育分布特征。结果表明,地震前后的崩塌发育具有空间聚集效应,在0~5.6 km范围聚集显著,但震后三年总体聚集趋势变化不大。此外,崩塌显著分布于高程2800~3400 m与30°~55°的陡坡段,地震触发与震前重力诱发崩塌分布在北东-南的优势坡向,而岩性上则集中在石炭系与石炭二叠系的厚层坚硬碳酸盐岩地层。本文研究成果对九寨沟景区崩塌灾害防治与风险管控具有积极意义,亦可为震后地质灾害长期活动性研究提供基础数据。

The“8·8”earthquake in 2017 struck the Jiuzhaigou World Natural Heritage Park,and trigged abundant high-level or very high-level collapses.Three years after the earthquake,the collapse still showed high activity,which caused serious damage to natural landscapes and tourist facilities.In order to reduce the threat of collapse to reconstruction and ecological restoration,based on five periods of high-precision remote sensing data before and after the earthquake,continuous field investigation,high-precision remote sensing interpretation and nuclear density analysis were used to research the spatial aggregation trend and development distribution characteristics from the perspective of time and space.The result shows that the collapse development has a spatial aggregation effect,and the aggregation is significant in the range of 0~5.6 km,but the overall aggregation trend within three years after the earthquake has not changed much.In addition,collapses are significantly distributed in the steep slopes with elevations of 2800~3400 m and 30°~55°.Earthquake triggers and pre-earthquake gravity-induced collapses are mostly distributed in NE-S.And the lithologically is concentrated in the thick and hard carbonate formations of C and CP.The research results can have a certain significance for the prevention and risk management of Jiuzhaigou's collapse disasters,it can also provide basic data for the long-term activity study of post-earthquake geohazard.