【作者】 余怀忠；

【导师】 沈正康；

【作者基本信息】 中国地震局地质研究所 ， 地质学， 2006， 博士

【摘要】 地震是一种严重的自然灾害,正确预测地震具有重要的意义。本课题通过以下研究,揭示地震孕育演化的物理机制,提高地震中短期预测水平。1)改进发展加卸载响应比理论(Load Unload Response Ratio)利用震前库仑应力增加区域取代传统圆形临界区域计算LURR,提高LURR临界敏感性。震前库仑应力场采用地震断层反向滑移模型计算。对近20年来美国南加州6.5级以上地震分析结果表明将LURR与震前应力触发模型相结合,能够明显提高LURR地震预测能力。建立地震预测概率模型量化LURR的预测结果。按照这一模型,未来地震的触发几率可通过LURR随机分布以概率的形式表现。对中国大陆、美国南加州、日本关东地区发生的40个震例的统计分析表明,地震发生率与LURR置信概率变化呈线性相关。这一结论表明本概率模型可能是量化预测未来大地震发生的重要方法。2)可可西里地震前的慢滑移事件定位研究使用“包络线相关法”对2001年11月14日中国青海可可西里7.8级大地震震前产生脉动信号的滑移进行定位。37个事件的定位结果显示慢滑移活动集中分布于可可西里地震震源区附近,深度为10 ~ 40公里。研究表明,慢滑移源可能发生于东昆仑断裂带内锁定层与蠕滑层间的转换层,慢滑移活动将部分应力负载转移至位于转换层上部的锁定层导致震源区相当范围内库仑应力快速增加,触发可可西里大地震。更多还原

【Abstract】 Strong earthquakes can be catastrophic to society, and precise prediction of large earthquakes is very important for seismic hazard reduction. In this study, we try to develop methods to quantify physical parameters associated with seismogenic processes, and use that to experiment enhancing the power of short-to-intermediate-term earthquake prediction. Specific works are the following.1)Improvement on Load/Unload Response Ratio methodWe replace the circular critical region usually adopted in LURR practices with an area within which the Coulomb stress change would affect the potential seismogenic fault of a future large event the most, to enhance the sensitivity of the LURR method. The Coulomb stress change before a hypothetical earthquake is calculated based on a simple back-slip dislocation model of the event. The results given by applying the approach to the Mw > 6.5 earthquakes occurred in California over the last twenty years suggest that the predictive power of the LURR method can be enhanced significantly by combining the LURR method with our choice of identified area with increased Coulomb stress.We develop a probabilistic approach for assessing earthquake potential based on the LURR method. In the approach, the triggering probability of a future earthquake given the confidence level of an anomalous LURR is quantitatively evaluated associated with stochastic distribution of LURR. By applying the approach to 40 large earthquakes occurred in the Chinese Mainland, southern California, and the Kato region in Japan, we find a linear increase of earthquake potential along with the confidence level of precursory LURR anomaly. The research results indicate that our probabilistic approach can provide a useful tool to quantitatively evaluate the possibilities of critical triggering of the future earthquakes.更多还原