Statistical Tests for Pre-earthquake Ionospheric Anomaly

1 Institute of Statistics, National Central University, Chung-Li, Taiwan, ROC 2 Institute of Space Science, National Central University, Chung-Li, Taiwan, ROC 3 Center for Remote Sensing and Space Researches, National Central University, Chung-Li, Taiwan, ROC 4 Institute of Geophysics, National Central University, Chung-Li, Taiwan, ROC * Corresponding author address: Dr. Yuh-Ing Chen, Institute of Statistics, National Central University, Chung-Li, Taiwan, ROC; E-mail: [email protected] The anomalous depression of the maximum plasma frequency in the ionosphere (foF2) appears significantly within 1-5 days before the M ≥ 5.0 earthquakes in the Taiwan area during 1994 1999 (Liu et al. 2003). In this paper, we propose two statistical tests against the foF2 anomaly as a candidate for a precursor of earthquakes based on criteria including the success rate, alarm rate, probability gain, and R score. One statistical test is conducted to investigate the significance of the observed foF2 anomalies related to the recorded M ≥ 5.0 earthquakes in the Taiwan area during 19941999. The other statistical test is designed to compare the foF2 anomalybased method with competitive alternatives for predicting the earthquakes under study. The involved alternatives are a naive prediction based on a coin-tossing experiment and a simple prediction method constructed from the current M ≥ 5.0 earthquakes catalog during 1994 1999. The simulation results indicate that, contrast to possible foF2 anomalies, the observed foF2 anomalies are significantly earthquake-related. Moreover, comparing with the alternative predictions under study, the foF2 anomaly remains valid for temporal alarming of the M ≥ 5.0 earthquakes in the Taiwan area during 1994 1999. (