統計研究1999-2017年環太平洋地區電離層地震前兆，分析9個地區：北美洲、中美洲、南美洲、日本、東海地區、台灣、菲律賓、印尼、紐西蘭共11363筆地震。首先透過全球電離層圖(Global Ionospheric Map, GIM)之全電子含量(Total Electron Content, TEC)判定電離層異常，並藉由Z檢定尋找各區域地震前兆出現之時間與異常特性，其後利用接受者操作特徵曲線(Receiver Operating Characteristic curve, ROC curve)評估Z檢定所選時間預警地震之可行性。統計結果顯示北美洲、日本、菲律賓、紐西蘭皆為正異常地震前兆，其中北美洲前兆為前24-26天2000-2300UT，紐西蘭為前10天內1800-2300UT，日本為前1-3天0600-1200UT，菲律賓為前4-6天；台灣、印尼則為負異常地震前兆，台灣地震前兆發生時間多為當地時間下午時段，印尼為前10天內負異常；中美洲、南美洲、東海地區地震前兆正、負異常皆存在，前兆出現時間皆無特定特性。ROC曲線分析結果證實隨著規模愈大，地震預警能力隨之增加，且環太平洋各區地震規模達到6.5以上會有顯著之地震前兆。

The statistical analyses are implemented on seismo-ionospheric precursors (SIPs)with the total electron content (TEC) of the global ionosphere map (GIM) associated with 11363 earthquakes in the circum-Pacific seismic belt including North America, Central America, South America, Japan, East Sea, Taiwan, Philippines, Indonesia and New Zealand during 1999-2017. The Z-test is applied to determine the criteria and characteristics of TEC anomalies related to earthquakes. The Receiver Operating Characteristic (ROC) Curve is further used to estimate the accuracy of SIPs. The results indicate that precursors above North America, Japan, Philippines, and New Zealand are all positive anomalies. In North America, the positive anomalies occur between 2000-2300UT within 24-26 days before earthquakes. In New Zealand, the positive anomalies occur between 1800-2300UT within 10days before earthquakes. In Japan, the positive anomalies occur between 0600-1200UT 1-3 days before earthquakes. In Philippines, the positive anomalies occur in 4-6 days. The SIPs with negative anomalies can been
found in Taiwan during afternoon (local time) and in Indonesia within 10 days. In addition, both positive and negative anomalies occur in Central America, South America, and East Sea. The results of ROC curve shows that the SIPs will be more accurate with the massive earthquakes. Once the magnitude of earthquakes are larger than M6.5 we can have significant SIPs in the circum-Pacific seismic belt.

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