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介绍了一种利用互相关和双差方法快速对新地震事件相对于过去已精确定位的事件进行高精度重定位的实时方法。本方法自动将新事件的波形记录与它附近发生过的已归档事件进行互相关,以精确测量震相到时的差分。利用双差算法将这些数据以及从到时拾取中计算出的延迟时间,转换成新事件与它相邻事件的相对位置向量。利用来自北加州地震台网(NCSN)和北加州地震数据中心近实时的数据,及当地储存的北加州地震台网地震档案的拷贝等数据,将这项新的监测技术应用于加州北部的地震记录。与加州北部高分辨率双差地震目录相关的新的事件将被进行近实时(几十秒内)自动重新定位。利用北加州已发生的事件进行逆向测试,结果显示实时双差定位结果水平向的分辨率平均为0.08km,深度方向为0.24km。研究发现,因为地震记录的密度会持续增加及数字地震档案的积累,利用本方法定位新事件的精度随着时间的推移将不断地得以改善。实时双差地震定位能以前所未有的分辨力来监测活动断层在孕震特征上的时空变化,因此它在快速评估及减轻地震灾害的过程中具有显著的社会和经济效应。
A real-time method of using the cross-correlation and double-difference methods to quickly relocate a new seismic event relative to the past precisely located event is presented. This method automatically correlates the waveform record of a new event with the archived events that occurred in the vicinity of it to accurately measure the difference between the phases of the arrival. These data, as well as the delay time calculated from the pick-to-pick, are converted into the relative position vectors of the new event and its neighbors using the double difference algorithm. Using this near-real-time data from the Northern California Seismological Network (NCSN) and the Northern California Seismic Data Center and copies of the locally stored North Sequoia seismic file, the new monitoring technique was applied to an earthquake in northern California recording. New events related to high-resolution double-difference seismic catalogs in Northern California will be automatically repositioned in near real-time (within tens of seconds). The reverse test was conducted using the events that occurred in Northern California. The results show that the average horizontal resolution of the real-time dual-difference positioning is 0.08km and the depth is 0.24km. The study found that as the density of seismic records continues to increase and the accumulation of digital seismic files, the accuracy of locating new events using this method will continue to improve over time. Real-time double-difference seismic positioning can detect the temporal-spatial variation of seismogenic features of active faults with unprecedented resolution, and therefore has significant social and economic effects in the rapid assessment and mitigation of earthquake disasters.