近台资料对近震相对定位算法的影响

从地震定位的基本原理出发，分析认为近台资料可用于双差定位算法，但不能用于其他相对定位方法.在此基础上，通过分析和模拟计算表明，应用近台资料时，双差法有可能给出一定精度的地震绝对位置.但仅采用近台资料时，相对位置的误差会比使用远台资料时有所增加.近台和远台资料的联合使用，有利于得到较为精确的定位结果.当震源深度远小于震中距时，如果没有深度震相的参与，只能得到误差较小的震中相对分布，深度的相对位置仍有较大的误差.对2003年新疆伽师地震余震序列中部分余震的重新定位试验，验证了近台资料对双差定位算法的上述影响.

Effect of the data recorded at nearby stationson earthquake relative location

Based on the fundamental theory of earthquake location, it is found that the data recorded at nearby stations are applicable in double difference relocation algorithm, but not in other relative location algorithms. Equation derivation and simulated calculation demonstrate that double difference algorithm allows us to get the absolute locations of earthquakes with certain accuracy by using the nearby station phase arrivals. The errors of relative location become larger when using the nearby station records alone than that using the distant station records. Combining the nearby and distant station records, the best locations are obtained. In the case that hypocenter depth is far less than the epicenter distance without depth phases available, only the relative epicenter distribution could be obtained accurately by double difference method, the depth determined would be not stable. The relocation test of a part of aftershocks in Jiashi earthquake sequence verified the effect of nearby station records on the double difference algorithm mentioned above.