日本地震前兆研究概况日本地震预报的研究和观测,最早只有大地测量、验潮、重力、地磁、地震活动、地形变等项目.日本地震预报第二个计划(1969-1973年),尤其是第三个计划(1974-1978年)期间,观测项目有很多增加(表1).地震观测分三类,即全国性观测、指定地区的强化观测和集中观测.在预报地震方面,又将地震前兆分为长期、中期和短临三个阶段,并以此把地 Japan earthquake precursory research overview Japan earthquake prediction research and observation, earliest only geodesy, tide, gravity, geomagnetic, seismic activity, terrain deformation and other projects.Japan earthquake prediction second plan (1969-1973), especially the first During the three plans (1974-1978), there were many observations (Table 1). There are three types of earthquakes, that is, nationwide observation and intensive observation in designated areas, and centralized observation. In the prediction of earthquakes, earthquake precursors Divided into long-term, medium-term and short-term three stages, and thus to the ground