福山大学で観測された地震動特性について : その2

概要

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Earthquake activity in Chugoku district is not so high that the number of felt earthquakes in a year seldom exceeds 10. The earthquake intensity rank of them are classified into slight or weak earthquakes. We have few information of real earthquakes in this area. To collect earthquake records for engineering use, since 1988 earthquake observation has been held at Fukuyama University using digital recording system with high precision and reliability. At the first stage of the observation, the accelerometers were located on the floor of a laboratory building, and the earthquake records may contain vibrational effect of the building. To avoid these effects the acceleometers were moved on the ground surface near the building. At the same time one accelerometer and one velocity transducer were added and three components of ground acceleration and one horizontal component of velocity were recorded when the system detected 1 gal or more acceleration. Six small earthquake records were obtained from the relocation of accelerometers. Although acceleration level of the observed earthquake motions are low, their vibrational characteristics are considered by the spectral analysis and some features of earthquakes in Chugoku district are poited out. The differrence between observed acceleration and velocity components of the same point is considered.