基于Newmark模型的积石山6.2级地震滑坡快速评估

Rapid assessment of landslides induced by the Jishishan M_(S)6.2 earthquake based on Newmark model

2023年12月18日甘肃临夏回族自治州积石山县发生6.2级地震,引发大量的滑坡和崩塌等地质灾害。基于黄土高原强震数据库中2013年岷县—漳县6.6级地震的地震动记录回归分析所得的Newmark位移预测模型,利用震前精度为30 m分辨率地形以及1∶250万地质图等数据,考虑竖向地震加速度以及冬灌的影响,对距震中扩展100 km范围内的地区进行滑坡危险性快速评估,并与震前地质灾害分布以及震后遥感解译和实地调查结果进行对比。研究结果显示:静态安全系数较低的区域更容易发生地质灾害;滑坡危险区主要位于距震中27 km的范围内,危险区内河道和分水岭发育,地层以新近系和第四系为主,与已有研究结果的重合度较高。研究表明,Newmark位移法适用于积石山区域内的震后滑坡危险性评价,但其并未考虑土体液化的情况,低估了液化灾害发生的危险程度。

On December 18,2023,an M_(S)6.2 earthquake hit Jishishan County,Linxia Hui Autonomous Prefecture,Gansu Province.This phenomenon induced numerous geological disasters,such as landslides and collapses.The Newmark displacement prediction model was first derived from the regression analysis of ground motion records of the 2013 Minxian-Zhangxian M S6.6 earthquake in the strong earthquake database of the Loess Plateau.Therefore,considering the vertical seismic acceleration and the influence of winter irrigation,a rapid assessment of landslide risk in the area within 100 km from the epicenter was conducted using 30-m resolution topography and a 1:2.5 million geological map before the earthquake.Assessment results were compared with the distribution of geological disasters before the earthquake and the results of remote sensing interpretation and field investigation after the earthquake.The comparative results reveal that areas with low static safety factors are prone to geological disasters.The landslide risk area is mainly located within 27 km from the epicenter,where the channels and watersheds are highly developed,and the strata mainly comprise Neogene and Quaternary formations,demonstrating high similarity to the existing research results.The study demonstrates that the Newmark displacement method is appropriate for assessing post-earthquake landslide risk in the Jishishan area.However,the Newmark displacement method overlooks soil liquefaction,thereby underestimating the degree of danger of liquefaction.