GNSS坐标时序异常情况讨论:以长宁地震为例

2019年6月17日四川省宜宾市长宁县发生MS6.0地震。在震前约60天,距离震中西南方约42 km处的筠连GNSS连续观测站(JUNL)坐标时间序列东方向开始出现异常变化,笔者所在工作组第一时间发现并落实了该异常,正式提交了异常核实报告。本文主要梳理了此次异常核实成功经验,为后续地震监测预报工作提供震例总结。异常出现后,工作组首先从原始时间序列、从多路径效应分析、天空残差视图对比分析等对JUNL站数据进行内业质量检测,排除数据质量问题。当天,工作组赶到台站进行现场异常核实,通过对仪器设备、观测室环境、观测场环境等进行检测,排除了仪器故障和环境干扰等因素。由于筠连站紧挨长宁珙县震群,且地震活动活跃,因此结合内、外业检测分析结果,工作组在震前22天作出筠连站异常与地质构造运动或断层活动有关的判断,为本次地震的预测预报工作提供了科学依据。

Discussion on the Anomaly of GNSS Coordinate Time Series:A case Study of the Changning Earthquake

The MS6.0 earthquake occurred in Changning,Yibin city on June 17th,2019.About 60 days before the event,an anomalous change began to appear in the eastern component of the coordinate time series of JUNL GNSS continuous observation station about 42 km south-west of the epicenter.The author's working group discovered and verified the anomaly in the first time,and formally submitted an anomaly verification report.The main purpose of this paper is to sort out the successful experience of this anomaly verification and provide a summary of earthquake cases for the follow-up earthquake monitoring and prediction work.When the anomalies are found,the data quality of JUNL station is checked from the original time series,multi-path effect and the comparative analysis of sky residual view to eliminate the factors of anomaly caused by poor data quality.Then,the working group immediately went to the station to verify the anomaly.Through the investigation of the GNSS instruments and equipment,the environment of the observation room and observation field and so on,the factors such as instrument failure and environmental interference were eliminated.Because JUNL station is close to the Changning-Gongxian,earthquake swarm having high active seismic movement.Combining with the results of internal and external inspection and analysis,the working group immediately(22 days before the event)made the judgment that JUNL station's anomaly is related to the movement of geological structure or fault activity,which provided a scientific basis for the Changning earthquake prediction.