Improvement of precision of waveform of the coherent seismic wave tomography method

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We have developed an active seismic underground tomography system based on a new-brand idea. In 1999 fiscal year, we designed and manufactured an advanced model of rotary seismic source that has much more capability than the old one. We had planed to deploy the new source in a test field in 2000 fiscal year ; it appeared soon that this deployment needs a lot of budget fund, though, because the experience of another trial of a rotary seismic source done by Nagoya University revealed that the continuity between the source and the supporting ground required a careful introduction of the anchorage devices. Fortunately, another research plan that aimed the deployment was accepted elsewhere and we could submit the present fund to the original target, improvement of the ability of the system.(1) Phased array of sources that realizes the coherent wave field requires not only the control of its velocity but also the control of its position. We realized this position control through a combination of an optical sensor and the encoder of the motor.(2) We carried out a laboratory experiment of scattering of elastic wave in rock specimens. The objective of this experiment was to provide materials to construction of models of scattering of elastic wave through stress concentration in the ground ; good scattering models are supposed to support inversion calculations.(3) We also analyzed mathematically the elastic wave in layered ground and established a formula that described the transformation to the emitted elastic wave energy from the electromagnetic energy submitted into the motor.