2020年云南巧家5.0级地震烈度评定及房屋震害特征

Intensity assessment and characteristics of buildings’damage in the afflicted area of 2020 Qiaojia MS5.0 earthquake in Yunnan

2020年5月18日巧家县发生5.0级地震,结合震区背景信息和现场调查,详细阐述此次地震烈度分布和房屋震害特征,并计算各类结构房屋的震害指数和破坏比。调查发现,本次地震的最高烈度为Ⅵ度,长轴呈NW向,与灾区地震地质构造背景、仪器烈度分布具有较好的一致性。对比分析本次地震与昭通地区、云南其他地区近年来大小相近的历史地震Ⅵ度区震害指数,结果表明,本次地震房屋震害指数相较于昭通其他地区明显偏低,但比云南其他地区偏高。分析认为,近年来巧家县各项房屋改造工程切实提高了当地房屋抗震水平,但仍需加强房屋改造建设,尤其是加快推进老旧房屋拆除及新房建设工作,进一步提升房屋抗震能力。

On May 18 th, 2020, an MS 5.0 earthquake struck Qiaojia county in Yunnan Province. Based on the seismotectonic settings and field investigations in the disaster area, we studied the seismic intensity distribution and the characteristics of the buildings’ damage caused by the earthquake. Then we calculated the damage indexes and damage ratios of the buildings. The maximal intensity in the meizoseismal area is Ⅵ and the shapes of isoseismic lines are oval with the long axis in NW direction, which is in good accordance with the strike of the seismogenic fault and the instrumental intensity. After comparing damage indexes in the Qiaojia earthquake area with that from other earthquakes with similar magnitudes in Zhaotong and other places in Yunnan Province, we found that the damage indexes of the Qiaojia earthquake are obviously lower than that of the earthquakes in Zhaotong city, yet higher than that in other places in Yunnan Province. It is clear that the seismic performance of the buildings in Qiaojia has been substantially improved after implementing the housing renovation project. To further upgrade the aseismic capacity of the buildings in Qiaojia, the local government should carry on the housing renovation project and, what’s more, speed up demolishing the old houses and building the new houses.