城市地震风险精细化评估--以北京海淀区为例

ASSESSING THE SEISMIC RISK OF CITIES AT FINE-SCALE:A CASE STUDY OF HAIDIAN DISTRICT IN BEIJING,CHINA

地震风险评估需充分考虑到地震风险的时空差异,选择合理的时空间尺度进行研究,才能给政府防灾减灾规划、政策的落实和应急救援等提供具有可操作性、切实有效的信息。为此,基于辨识城市地震风险时空格局差异以及抗震救灾组织2个方面的综合考虑,本研究选择在500m×500m格网尺度上进行昼夜2个不同时段的地震风险评估研究,建立了昼夜人口分布与土地利用的对应关系,以及建筑物损毁与人员伤亡之间的关系,提出了昼夜地震风险精细化评估的方法。并以北京市海淀区为例,在500m×500m格网尺度上进行了地震风险的模拟评估,估算了海淀区总体及格网在相应的地震烈度下可能的建筑物损毁面积、房屋损失以及人员伤亡数。结果表明,海淀区年期望建筑物损毁总面积为18.5万m2,房屋总损失为3.25亿元(不包括屋内财产),白天死亡总人数3158人,受伤总人数12071人,夜晚死亡总人数2037人,受伤总人数7790人;空间上,建筑物损毁面积和房屋损失比较大的地区集中在南部城市中心区和东部产业园区,白天和夜晚伤亡人数自东南向西北呈现出显著的"城市核心区—城市边缘区—城市影响区—乡村腹地"的衰减模式,白天伤亡人口有几个显著的高值区,夜晚伤亡人口则分布相对分散。文中的分析结果识别了昼夜精细化尺度地震风险的高值区域,为进一步确定防震减灾、震后应急救援以及各种救灾物资分配的重点地区提供了决策依据。

In order to provide practical and useful information for the disaster prevention and relief actions,it is necessary to take into account spatial differences and temporal changes of seismic risk in evaluating seismic risk at a proper temporal and spatial scale. From the perspectives of identifying spatial difference of seismic risk within the city and performing disaster relief operations, the evaluation of urban seismic risk is done in this paper at the spatial scale of 500m＊ 500 m grids for day time and night time separately. For this purpose,this paper proposes the methods for the assessment of seismic risk,establishing the correspondence relations between the population and land use,and between the floor area of buildings destroyed and casualties at more reasonable spatial and temporal scales. Taking a case study of Haidian District in Beijing using these methods,we estimate the floor area and the value of buildings destroyed and the casualties at daytime and nighttime separately at the500 m grid scale. Results show that： a total of 185,000m2 of areas is expected to be destroyed annually in Haidian District,and the total loss of the houses is 325 million Yuan（ excluding properties within the houses）. During the day（ night） time,3 159（ 2 037） victims are expected to be killed and12 071（ 7 790） injured. Destruction of buildings and loss of houses is spatially concentrated in the downtowns in the south and the industrial parks in the east. The casualties inflicted during the day and night descend from southeast to northwest,i.e. from urban core areas,urban fringes,urban outskirts,to village. Several regions suffer heavy casualties during the day,but nighttime casualties are scattered across different regions. The conclusions in this paper efficiently identify the spatial distribution of areas at the level of high and the very high seismic risk,which provides reliable decision support for identifying priority areas for pre-disaster prevention and mitigation, emergency rescue and the distribution of various relief supplies.