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

我们基于一种全新的理念开发了一种有源地震地下层析成像系统。在1999财政年度，我们设计并制造了一种先进的旋转震源，其性能比旧的要大得多。我们曾计划在2000财年在试验田部署新的震源；但很快看来，这一部署需要大量预算资金，因为名古屋大学进行的另一次旋转地震源试验的经验表明，震源和支撑地面之间的连续性需要仔细引入锚定设备。幸运的是，另一项针对部署的研究计划被别处接受，我们可以将目前的资金提交给最初的目标，提高系统的能力。(1)实现相干波场的相控阵震源不仅需要控制其速度，还需要控制其位置。通过光学传感器和电机编码器的结合，实现了这种位置控制。(2)开展了弹性波在岩石试件中的散射实验。本实验的目的是为建立弹性波通过地面应力集中的散射模型提供材料；良好的散射模型应该支持反演计算。(3)对层状地基中的弹性波进行了数学分析，建立了描述进入电机的电磁能量向发射的弹性波能量转化的公式。

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.