【摘要】 加卸载响应比是一种中短期地震预测方法.按照该方法,通常在大地震发生之前加卸载响应比时间序列会出现明显的异常高值.早先的研究发现,震前临界区域的选择对加卸载响应比的计算有很大影响.我们发展了一种使用震前应力积累区域取代传统圆形区域计算加卸载响应比的算法,提高了加卸载响应比的地震预测能力,其震前库仑应力场分布采用地震断层位错模型将同震滑移量反向滑移的方法计算.美国南加州近20年来发生的4次M>6.5地震以及2008年中国汶川MS8.0地震的研究事实表明,使用库仑应力算法得到的加卸载响应比时间序列,前兆变化相对于圆形区域算法更为明显,且对目标地震的位置、震级预测更为明确.库仑应力算法的这一独特性质,使我们可以针对不同地区的活动构造特征对未来地震发生的地点和大小提供信息和约束.更多还原

【Abstract】 The load/unload response ratio (LURR) is a short-to-intermediate-term earthquake prediction method. Using this method,the LURR time series usually climb to an anomalously high peak prior to occurrence of a large earthquake. Previous studies have indicated that the size of critical seismogenic region selected for LURR measurements has great influence on the evaluation of LURR. We replace the circular region usually adopted in LURR practice with an area,within which the tectonic stress change would mostly affect the Coulomb stress on a potential seismogenic fault of a future event. This new algorithm is devised to improve the predictive power 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. Retrospective tests of this algorithm on four M>6.5 earthquakes occurred in California over the last two decades and the 2008 MS8.0 Wenchuan earthquake,show that the anomalies produced by the Coulomb stress algorithm look more prominent than the ones produced by the circular region algorithm. Moreover,The Coulomb stress algorithm seems to be more sensitive for detecting future earthquakes of particular magnitude range and location than the circular region algorithm. The unique feature of the Coulomb stress algorithm may provide information and constraints on forecasts of the size and location of future large events based on the regional tectonic activities.更多还原