摘要
震后快速产出的震动烈度分布是地震应急救援非常有效的依据,通常由烈度与地震动参数的经验关系给出.有台站的场点,地震动参数可以直接由台站数据给出确定性的结果;而无台站的场点,地震动参数只能由衰减关系给出估计值.目前我国台站覆盖有限,且难于实时获取,快速生成的地震动参数主要依赖于地震动衰减关系,再依据烈度与地震动参数的经验关系,输出确定性的震动烈度分布.由于衰减关系本身存在着不确定性,将其估计值用于生成确定性的震动烈度分布是不准确的.而且实践证明,震动烈度与实际调查烈度存在差异.鉴于此,从衰减关系模型中的ε出发,提出了场点(城镇)遭遇不同烈度的概率计算方法:利用衰减关系的估计值与衰减关系的标准差,构造峰值加速度(PGA)变化的对数正态分布,然后以烈度分档对应的PGA范围,计算震区各城镇遭遇不同烈度的概率及各城镇抗震设防烈度被超越的概率.具体以1966年3月8日河北邢台MS6.8地震为例,说明了此方法的可行性,认为以概率形式给出城镇可能遭遇的烈度在表述上更为合理,并建议将场点(城镇)遭遇烈度的概率表达方法用于震害快速评估.
Shaking intensity distribution immediately following an earthquake is valuable for emergency response. Such intensity distribution is usually derived from empirical relationship between seismic intensity and ground motion parameters. If there is a seismic station at the site, the ground motion parameter is quantified by the station record; if there is no seismic station, the ground motion parameter is just estimated from attenuation relationship. Due to the sparse seismic station coverage and the difficulty in real-time data acquisition in China, the rapid results of ground motion parameter, which will be changed into shaking intensity later according to empirical relationship between seismic intensity and ground motion parameter, are just estimated from attenuation relationship. However, there is uncertainty in attenuation relationship itself, the estimated ground motion parameter is dubious and is not suitable to be used for the output of the deterministic shaking intensity distribution. Therefore, we propose a method to compute the probability of shaking intensity for counties in seismic area by means of the stochastic variable ε in attenuation relationship. Specifically, we build the logarithmic normal distribution about peak ground acceleration, using the estimated value and the standard deviation of the attenuation relationship, to calculate the probability of every possible shaking intensity and the probability exceeding seismic fortification intensity for counties in seismic area. Then, the March 8 1966 Xingtai MS6.8 earthquake is taken for example to show the feasibility of this method. It is thought that the intensity displayed in a probability way is more reasonable than before. So, it is recommended that the intensity characterized by probability should be considered in emergency response and rapid earthquake damage assessment.
出处
《地震学报》
CSCD
北大核心
2013年第4期553-560,2,共8页
Acta Seismologica Sinica
基金
地震行业专项(201108002
201108014)
基本科研业务(DQJB11C26)共同资助
关键词
震动烈度
调查烈度
抗震设防烈度
衰减关系
发生概率
超越概率
shaking intensity
survey intensity
seismic fortification intensity
attenuation relationship
probability of occurrence
exceedance probability
