NOTES ON A LONG-PERIOD SEISMOGRAPH SYSTEM WITH RC NETWORK

NOTES ON A LONG-PERIOD SEISMOGRAPH SYSTEM WITH RC NETWORKTakeshi MIKUMOAbstractCharacteristics of a long-period seismograph system with RC network are described. Thesystem consists of an electromagnetic seismograph of Press-Ewing type, resistance-capacitancedouhle integrating network, DC amplifiers, and a rectilinear ink-writing galvanometer with a long-duration recorder. This study includes theoretical evaluation of the behavior of a condenser-shunted pendulum, the transfer characteristics of the RC network and of the overall systemresponse. Experimental procedure by applying a calibration signal with steady state or stepfunction current to an auxially coil leads to determination of the amplitude and phase responsesof the system to the ground acceleration and hence the ground displacement. The impulseresponse of the system and theoretical waveforms for the incidence of impulsive P and SV wavesat the base of the crust, are computed for later discussions. Examples of the seismograms from adistant earthquake and aftershock sequences are also presented.NOTES ON A LONG-PERIOD SEISMOGRAPH SYSTEM WITH RC NETWORKTakeshi MIKUMOAbstractCharacteristics of a long-period seismograph system with RC network are described. Thesystem consists of an electromagnetic seismograph of Press-Ewing type, resistance-capacitancedouhle integrating network, DC amplifiers, and a rectilinear ink-writing galvanometer with a long-duration recorder. This study includes theoretical evaluation of the behavior of a condenser-shunted pendulum, the transfer characteristics of the RC network and of the overall systemresponse. Experimental procedure by applying a calibration signal with steady state or stepfunction current to an auxially coil leads to determination of the amplitude and phase responsesof the system to the ground acceleration and hence the ground displacement. The impulseresponse of the system and theoretical waveforms for the incidence of impulsive P and SV wavesat the base of the crust, are computed for later discussions. Examples of the seismograms from adistant earthquake and aftershock sequences are also presented