A Practical Prediction Method of Major Earthquakes

This chapter determined to use the data base of the Hi-net seismic observation network of National Research Institute for Earth Science and Disaster Resilience (NIED) which was developed to be used for development of methods of earthquake prediction.

The study tried to find a practical method of prediction of major earthquakes as life work (of Fujinawa) for more than 40 years to prevent huge disasters. Many countries, especially earthquake-prone countries have been involved to find practical methods more than half of a century. But there are still no practical methods despite great efforts. There spreads general pessimistic atmosphere against positive stance to the earthquake prediction with the result of decrease of number of scientists and engineers interested in the investigation. With the exception of two exceptional occurrences with the result of a generally pessimistic appraisal, attempts to create the prediction, one of the most effective ways based on current scientific method, have been made during the past fifty years. When compared to other phenomena, the study of seismic activity has been the one that has been approached the most. Especially foreshocks are investigated enough to provide many useful results, there is critical defect of unstable occurrence. On the other hands important progress is attained in the laboratory investigation of nucleation process providing important results. However, those result cannot be confirmed by field observation just before occurrence of major earthquakes. Earthquake-prone countries are recommended to have seismometer network having seismometers network as the High-net to record the high frequency tremors. At first simulation is recommended using small scale Hi-net in own country.

Here we make a special seismic catalog of high frequency tremors deduced anew from continuous seismic data of just before major earthquakes using the extensive network, High-net of Japan. Analysis of the catalogue for three big earthquakes and one slightly lesser one reveals three distinct precursory events, the first at around six weeks, the second at about four weeks, and the third right before the earthquake. And at each point of identifying those precursors, the three factors of prediction—time, place, and magnitude—can be distinguished precisely enough to guide actual disaster prevention actions.