Precursory Anomaly Detection of Jiuzhaigou M7.0 Earthquake Based on ARIMA Model

This paper used the time series method of ARIMA to detect the precursory anomalies from the low frequency electromagnetic average data recorded by 14 AETA stations within the range of 500 km from the epicentre 15 days before the Jiuzhaigou M7.0 earthquake. The results show that within 15 days before the earthquake, 9 AETA stations within 500 km from the epicenter appear anomalies. From the thermodynamic map of 14 stations' data anomalies, it can be seen that the abnormal phenomena of 4 stations lasted for more than 9 days, in particular, the Songpan seismic station experienced significant anomalies at 3~5 d before the earthquake. From the geographic distribution of abnormal stations, it can be seen that the abnormal phenomena of 4 stations lasted for more than 9 days. The 9 stations with obvious anomalies in the 14 stations are located near the first-level plate boundary of the mainland of China.