Development of Strong-Motion Observation Network Adaptable to Earthquake Education for Citizens and Students

截至1991年2月下旬，在东京都内的9个地点共设置了11台SMAC-B2型强震仪。观察地点包括两所公立初中、三所私立高中、三所大学和一个社区中心。1987年的房总半岛九州岛海岸地震和1990年的伊豆-大岛地震等几次强震都是由该观测网观测到的。为了便于对观测网记录的强震加速度图进行模拟处理，我们研制了一套由微机和扫描数字化仪组成的半自动数据处理系统。处理包括1）加速度记录的数字化，2）数字化数据的校正，例如基线和弧校正，3）波形分析，例如RT转换和响应谱分析，以及4）分析结果的可视化输出。以一组40秒的纪录进行数码化及一系列分析所需的时间，最多约为一至两小时。该数字化系统比传统的数字化系统对模拟加速度记录进行数字化所需的时间要少得多，而且在多点采集加速度记录的情况下，数字化和分析的结果可以通过简单的指令反馈到学校和社区中心。另外。1)此外，还开展了中等地震时学校建筑物受损情况调查、2）制定学校疏散标准、3）地震动特性与初中地震受损情况关系调查、4）向教师讲授减轻地震灾害的相关知识等活动。强震观测和上述四项活动被认为是有益的地震教育。

As a strong motion observation network, eleven SMAC-B2 accelerographs have been installed at nine sites in the Tokyo Metropolitan area upto late February, 1991. The observation sites include two public junior high schools, three private high schools, three universities, and one community center. Several strong ground motions were observed by this observation network on the occasions of such as Kujukuri Coast of Boso Peninsula earthquake of 1987 and Near Izu-Ohshima Island earthquake of 1990.A semi-automatic data processing system consisting of a personal computer and a scanning digitizer has been developed in order to make it easy to digitize analog strong-motion accelerograms that are recorded from the observation network. The processing consists of 1) Digitization of accelerograms, 2) Corrections of the digitized data such as base-line and arc corrections, 3) Wave analyses such as RT conversion and response spectral analyses, and 4) Visual output of the analytical results. The time required for the digitization followed by a series of analyses on a set of 40-second record is about one to two hours at most. The time is much less than that required for digitization of an analog accelerogram by means of conventional digitization systems.When accelerograms are obtained at many sites, the digitized and analyzed results have been fed back to the schools and community center with simple instruction. In additions. 1) Investigation of damage to school buildings in moderate earthquakes, 2) Development of school evacuation criteria, 3) Investigation of relation between ground motion characteristics and earthquake damage to junior high schools, and 4) Lecture to teachers on earthquake disaster mitigation, were also conducted. The strong motion observation and the above four activities have been found to be useful for earthquake education.