近几年在日本和世界上发生了许多严重的地震灾害。事先没有预警而发生的较大地震仅几分钟就可夺去很多人的生命,并摧毀许多城市。生活在常发生较大地震国家里的人们盼望着有朝一日有可能预报出何时何地会发生较大地震,以便把损失减少到最低限度。位于环太平洋地震带的日本是世界上最易发生地震的国 In recent years, there have been many serious earthquakes in Japan and the world. The large earthquakes that occurred without warning in advance took many people’s lives and destroyed many cities in just a few minutes. People living in countries where major earthquakes often occur are looking forward to the day when it is possible to predict when a major earthquake will occur and where to minimize the damage. Japan, located in the Pacific Rim, is the most vulnerable country in the world