多事件联合与双差地震定位方法研究：以朝鲜核试验定位为例

双差定位法（Double-difference Earthquake Location，简称DD）和多事件联合定位法（Joint Hypocenter Determination，简称JHD）是精确多事件定位中常用的两种方法.对震源机制相近的相邻事件，DD方法利用事件之间的相对到时精准地反演它们之间的相对位置，到时差数据能够利用波形互相关等方法直接测量，但是却无法准确地确定绝对位置；相比之下，JHD方法能够同时反演事件的绝对位置和台站走时校正值.结合两种方法的优点，本文提出一种混合定位方法，同时利用绝对到时数据和到时差数据准确地反演事件绝对位置和台站走时校正.本文利用模拟数据对该方法进行了验证并将其应用于朝鲜核试验定位，结果表明该方法能够有效减小走时计算误差所导致的定位误差.对于朝鲜核试验，相比单次事件+DD定位方法和JHD方法，相对Myers的定位结果定位偏差分别减小45.67%和40.00%.

The research of the joint hypocenter determination and double difference location: A case study on nuclear tests in North Korea

Both the double-difference event location (DD) and the joint hypocenter determination (JHD) algorithms are widely used approaches for accurate multiple events location. For a set of nearby events with similar focal mechanism, the DD method can precisely and accurately determine their relative locations by using differential arrival-time measurements at various stations directly measured through cross-correlation approach, nevertheless, it cannot precisely determine their absolute locations. In comparison, the JHD method simultaneously determines the absolute locations of the events cluster as well as station travel-time corrections. Combining the advantages of the two methods, in this paper a hybrid approach is presented to precisely determine the absolute locations of the events and station travel time corrections simultaneously by using both absolute arrival time and differential arrival-time measurements. The hybrid method is validated using simulated data and applied to North Korean nuclear tests. Results obtained show that this method can significantly reduce location errors caused by predicting errors of travel times. For North Korean nuclear tests, the overall location deviation relative to Myers is reduced by 45.67% and 40.00% compared with the single event + DD location method and JHD method, respectively.