Precisely and actively seismic monitoring
精密主动地震监测

It is a dream for seismologists to explore crustal structures and monitor its temporal variation with artificial seismic sources. The Precisely and Actively Seismic Monitoring(PASM) system introduced in this paper may supply an approach to this dream. It is based on Controlled Accurate Seismic Source(CASS) that generates seismic signal by the rotation of two eccentric masses, while their rotation is accurately controlled by GPS synchronized electronic system, the signal radiated by the source is precise and highly repeatable. This kind of signal is suitable for surveying crustal structures, especially for monitoring the temporal variation of crustal media characteristics. The operation of the source has no harms on the surrounding medium as the energy intensity radiated by it is quite small, it may be operated continuously for long time. The useful data may be obtained at the sites more than 150 km away from source by PASM system which is based on the source, includes highly sensitive digital seismic observation system, special data processing method, and signal to noise ratio improvement method. The accurate travel time temporal variation may be calculated by the cross-correlation of phase waveform group at the accuracy of 10-4~10-5 with the data. In this way, the accurate temporal velocity variation and media parameters may be dynamically monitored. It is a new and prospective technology for seismology.