中文摘要：

应用双差定位方法（hypodd）对北美Loma Prieta地区的分属于3个地震丛集的47个地震进行了精确定位．采用交叉谱法精确求取信号的走时差；同时采用人机联做方式在时域调整、修正按自动方式无法准确提取时差的信号，确保每个事件对的走时差精度．重定位后，在几百米的范围内，原来相互重叠的震源位置聚集为三个明显分离的丛集；水平方向的相对位置平均误差为8．5米，震源深度方向的平均误差为23．4m．

英文摘要：

We use the Double-Difference （1313） method to relocate 47 earthquakes from Loma Prieta, California. The events chosen in this study have previously been well identified as members of three multiplets, each made up of a cluster of nearly identical microearthquakes （magnitudes from 0.9 to 2.0）. Prior to the relocation, each of these overlapping clusters each had a radius measuring 200m or larger. The relocation reduces the cluster radii by approximately an order of magnitude, resulting in three well-separated micro-clusters. The estimated relative epicentral error of the relocated events is 8. 5 m while the corresponding depth error is 23.4 m.