抄録
The seismic activity in the Kanto-Tokai districts was examined by introducing a new monitoring procedure based on composition of statistical parameters. The parameters selected were b-value, υ-value (the parameter representing an earthquake occurrence pattern), and averaged P- and T-axis directions. These parameters, all of which can be derived directly from seismic data, have specific characteristics, and are considered to represent the state of local crustal activity. The entire Kanto-Tokai area was partitioned into 57 small regions, and each parameter was calculated for every region from the period of March 1986 to October 1989, with use of a seismic database of the National Research Institute for Earth Science and Disaster Prevention. By setting appropriate threshold values to variations for each parameter, anomalous periods were sought. The final result is represented by a weighted summation of anomalous periods. Although each parameter may have its own particular statistical fluctuation, the synthesis of all the parameters should present a statistically reliable measure of anomalous seismic activity. We recognized several anomalous periods which corresponded well with occurrences of moderate sized earthquakes. The result suggests this monitoring may be used in application to earthquake prediction.
