|Evaluation of the short-term earthquake prediction method (Kushida-Method) using FM radio waves|
Yoshino, C.; Nagao, T.; Uyeda, S. (1999). Evaluation of the short-term earthquake prediction method (Kushida-Method) using FM radio waves. Bull. Inst. Oceanic Res. & Develop., Tokai Univ. 20: 41-60
In: Bulletin of Institute of Oceanic Research and Development. Tokai University. Tokai University. Institute of Oceanic Research and Development: Shimizu. ISSN 0289-680X, more
|Authors|| || Top |
- Yoshino, C.
- Nagao, T.
- Uyeda, S.
Short-term earthquake (EQ) prediction research based on possible electromagnetic precursors in a wide frequency range has become active in recent years. In this paper, we examined the validity of Kushida's Ionosphere Monitoring Method. It is claimed that FM radio waves from stations beyond the line of sight can be received before EQ at Yatsugatake South Base Observatory when the epicenter is in a sensitive region determined by the location of the concerned FM station relative to the observatory, and that these anomalously received FM waves are back-scattered by temporary disturbance of the ionsphere above epicenters, as in the case of meteorite penetrating into the ionsphere. Based on this premise, most parts of Japan are covered by sensitive regions by tuning to various FM radio stations. This Ionosphere Monitoring Method has been conducted since the Januay 17, 1995 Hyogo-ken Nanbu EQ (magnitude, M: 7.2), i.e., the Kobe EQ and an EQ Precursor Detection Experiment was initiated in August, 1995, with the aim of predicting M>6 EQ. In this paper, after a brief introduction of the method, we report the results of its evaluation based on about 300 Observation Information Letters of the Earthquake Precursor Detection Experiment issued during the period of July 25, 1995 - Dec. 31, 1997. Prediction was judged successful when 1) the actual epicenter was in the predicted region, 2) the actual M was within 0.5 of the predicted M and 3) the time of occurrence was within the predicted time interval. The main results are:1) There was always detectable precursors for M>5 EQ and 90% of predictions predicting M>5 EQ were followed by some correlatable EQ activity.2) The success rate of predictions predicting M>5 EQ was 79% for epicenter, 34% for M and 47% for time.The overall success rate for the three factors was 11%.3) The alarm rate for M>5 EQ was 83% for epicenter, 17% for M and 39% for time. The overall alarm rate for the three factors was 9%.These results indicate that the Kushida method is the most effective for predicting epicenters, which may be naturally expected of this method which recognizes precursors in back-scattered waves from specific sensitive regions. Although the rates for M and time are lower, they are still good since the criteria for success are quite stringent. Information on whether or not a major EQ will hit a certain region within the immediate period of several days or a few weeks would undoubtedly be extremely useful for the general public. Strengthening of the observation system and clarification of the underlying physical mechanism of the concerned phenomena through multidisciplinary cooperation in the future would be highly desired.