1. 中国地震局工程力学研究所 地震工程与工程振动重点实验室,黑龙江 哈尔滨 150080;2. 地震灾害防治应急管理部重点实验室,黑龙江 哈尔滨 150080
1. Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics,China Earthquake Administration, Harbin 150080, China; 2. Key Laboratory of Earthquake Disaster Mitigation, Ministry of Emergency Management, Harbin 150080, China.
2023 年 12 月 18 日甘肃省积石山县发生了 Ms6.2 地震，与以往同等级地震相比，其表现出“同震重灾”特征和 引发了特殊流滑地质灾害。通过现场震害调查、走访受灾群众和搜集地质资料及相关文献，重点探讨了本次地震 的发震背景和孕育地质条件，对比了宏观烈度分布特征及与仪器烈度差异，统计了不同民居房屋的典型震害特征 及所占比例，调查了造成人员伤亡的主要成因；踏勘了次生流滑灾害宏观特征，对揭示其成因与触发条件提出了若 干关键问题。结果表明：宏观与仪器烈度具有较为明显差异，原因主要为地形地质条件复杂、不同乡镇经济发展水 平与房屋抗震设防能力差异及烈度仪布设缺乏统一标准；强震观测记录地表加速度明显大于 2021 年漾濞 Ms6.4 地 震，烈度Ⅵ、Ⅶ、Ⅷ区面积分别为 2022 年芦山 Ms6.1 地震的 2.3、1.5、2.5 倍，为造成同级地震重灾的一个重要成因；泥 流掩埋摧毁房屋、炕头相连淋浴间隔墙倒塌及地震发生在深夜是造成本次地震人员伤亡重的重要因素。流滑区域 长约 3 km，前后高程差约 85 m，总面积约 39 万 m2，漫出地面约 3 m 高，塌陷区残留若干孤岛，其可能为长期农田灌 溉、地下水体富集、地震主振方向与泥流运动和天然沟谷方向相同等外在因素和黄土湿陷、土体液化等内在机理综 合诱发，具体成灾诱因、物理机制和触发条件需多种手段联合验证。调查证明，按照抗震设防标准进行房屋建设和 既有建筑加固，强化农村居民防震减灾意识和应急避难知识，是减轻地震造成人员伤亡的有效措施。
On December 18， 2023， an earthquake of magnitude Ms6.2 occurred in Jishishan County， Gansu Province， which showed the characteristics of "same?seismic level and heavy disaster" and trig? gered special flowslide geologic hazards compared with previous earthquakes of the same magnitude. Through the on?site seismic damage investigation， visiting the affected people and collecting geologi? cal data and related literature， we focused on the background and breeding geological conditions of this earthquake， compared the distribution differences between instrumental intensity and macro?intensity， counted the typical seismic damage characteristics of different residential houses and their proportion， and investigated the main causes of casualties； we also surveyed the macro features of secondary flow? slide disasters， and raised some key questions about their causes and triggering conditions. A number of key questions were raised to reveal its causes and triggering conditions. The results show that there are obvious differences between the instrumental and macroscopic intensities， which are mainly due to the complex topographic and geological conditions， the differences in the economic development level of different towns and townships， the differences in the seismic?resistant capability of houses， and the lack of a consistent standard for the deployment of the intensity instrumentation； the surface accelera? tion recorded in the strong?seismic observation is obviously greater than that in the 2021 Yangbi Ms6.4 earthquake， and the area of Intensity Zones VI， VII， and VIII is 2.3， 1.5， 2.5 times that of the 2022 Lushan Ms6.1 earthquake， respectively. which is an important cause of the same magnitude earthquake causing severe damage； the flowslide buried and destroyed the houses， the walls of the kangtou?connected showers collapsed， and the earthquake occurred in the middle of the night are the main factors of the heavy casualties of this earthquake. The flowslide area is about 3 km long， with a difference in elevation of about 85m between the front and back， covering an area of about 390，000m2 and spreading out to a height of about 3m above the ground， with a number of isolated islands remain? ing in the collapse area， which may be triggered by a combination of external factors such as long?term irrigation of farmland， enrichment of the underground water ， and the direction of the seismic main vi? bration being the same as that of the flowslide movement and the natural valley direction， and the in? trinsic mechanisms such as wet subsidence of loess and liquefaction of the soil， and so on， and the spe? cific causes of the disaster， the physical mechanisms， and the triggering conditions need to be verified jointly by various means. The survey proved that building and reinforcing existing buildings in accor? dance with earthquake?resistant standards and strengthening rural residents' awareness of earthquake prevention and mitigation and their knowledge of emergency evacuation are effective measures to re? duce the casualties caused by earthquakes.