Regional Characteristics of Geomagnetic Variations Associated with Earthquakes in the Qilian Mountains

概要

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The transfer function of short periodical geomagnetic events (geomagnetic storms, bay and impulses) in the Qilian mountains, which are a seismically active region was analyzed to investigate the relationship between its temporal change and the local seismicity. The results for the Lanzhou observatory between 1975 and 1982 suggest that precursory anomalies occurred before the large and moderate earthquakes near the Lanzhou region. The coefficient A decreased before the earthquakes. Similarly, precursory anomalies of the transfer function also occurred in the results for Hexibao observatory before the local moderate earthquakes between 1980 and 1984. In that case earthquakes occurred after the decrease succeeded by the increase of A and B values. The truth rate for these two observatories cannot be explained by a random model of earthquake occurrence in the seismic active region near the Qilian mountains. The decrease in A can be explained by the decrease of amplitude in the vertical component of the geomagnetic field change before the earthquake.
独立行政法人防災科学技術研究所の論文
1993-03-29