回転成分地震計の改良と観測された回転成分地震波の性質

概要

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We have developed rotation seismometer using four translation seismic sensors (L22d), which have the same amplitude and phase characteristics. A negative input impedance amplifier and band-pass filter have eliminated mechanical deviations of individual sensor and adjusted to have suitable characteristics. Temporal earthquake observations have executed using translation and rotation sensors, at three places, which have different surface geology. They were Mitsuishi (MUJ), Obihiro (OBI), and Usu volcano (SWZ) in Hokkaido. We demonstrate some seismograms of rotation and translation components. Between maximum amplitudes of rotation (Ar) and translation (At), an emprical formula; Log Ar=p Log At (1) has been found, and p takesdifferent value for each observing site. We have obtained p value to be 1.39 for MUJ, and 1.29 for OBI, from local earthquakes seismograms. At SWZ, we obtained 0.84 from volcanic swarm type seismograms, which contains some low frequency type.
2006-03-15