Strong motion observation by Earthquake Research Institute : attainment and future

Strong motion observation has been started in 1965 by strong motion seismograph observation center and was improved by Strong motion observation office in 1994. Author has been concerned with many strong motion observations by used of SMAC type and so on, maintains of observation stations and data archives of strong ground motion from 1970. When the digital seismometer replaced SMAC type, it was developed strong motion observation network in Izu Peninsula and around Suruga Bay in 1981 and strong motion observation network in Ashigara Plain in 1987. Many urgent aftershock observations and damage investigations has been carried out over 40 years in severe earthquake area. These strong motion observations are reviewed for next generation in this paper. And, a reorganized plan of strong motion observation network is introduced.＜総説＞通常投