Abstract:Through the deep processing of the original station displacement time series data of 43 GNSS continuous stations in Yunnan from January 2011 to December 2018, based on the calculation of the strain parameter grid time series, the surface strain/maximum shear strain short-term anomaly indicators suitable for the short-term and imminent prediction of M≥5.0 earthquakes in Yunnan area are extracted respectively. Based on 27 earthquakes with M≥5.0 that occurred during the period, we use the R value scoring method to evaluate the predictive efficiency of the anomaly indicators. The results show that: 1) Two anomaly indicators have a good indication of the occurrence time of M≥5.0 earthquakes in Yunnan area. 2) When the forecast window length is set to 30 or 60 days, the prediction accuracy of the short-term and impending anomaly index of the maximum shear strain is higher than that of the surface strain under the same prediction window length. 3) Through the comparison of different prediction window lengths on the same anomaly index, we find that the best prediction window length of the surface strain short-term and imminent anomaly index is 90 days (for 27 earthquakes, 23 were reported correctly and 4 were missed. The predictive accuracy rate is 85.19%), and the best prediction window length of the short-term impending abnormality index of the maximum shear strain is 60 days (23 correct reports, 4 missing reports, and the predictive accuracy rate is 85.19%).
YANG Jianwen,YE Beng,CHEN Jia et al. GNSS Continuous Observation Short-Term Anomaly Index Extraction and Effectiveness Evaluation in Yunnan Area[J]. jgg, 2021, 41(9): 973-978.