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| | Abstract | | The seismic ACROSS (Accurately Controlled and Routinely Operated Signal System) using rotation of an eccentric mass is controlled source designed to obtain ultra stable signal for long duration as several years. This system is placed at a fixed location. The authors have developed mobile seismic source using electro-magnetic vibration. To modify our system to stable seismic source for long duration, we have begun to make system similar to the ACROSS. We used 10 MHz signal obtained by the GPS clock to obtain accurately frequency. The sweep is 10-50Hz during 100 seconds and 5 second rest time. One hour time frame is composed of 34 sweeps. Division of receiving seismic records and 420 seconds of source signal, we can obtain the transfer function. The experiment in Tochigi Prefecture showed nice P and S arrivals and indicated effectiveness of this source. We will continue to improve the system to obtain stabilities for long operation. |
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