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On the study of high resolution electromagnetic prospecting using the wave field transfomation

波场变换高分辨率电磁勘探研究

基本信息

批准号：
06651098
负责人：
MOGI Tohru
金额：
$ 0.77万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06651098/
关键词：
wave field transform electromagnetic prospecting

项目摘要

The summary of results of the study is as follows ;1. I have studied the wave field transfomation with the spline approximation. I specially paid attention to number of terms and sampling interval in the spline approximation. A peculiar oscillation was sometimes appeared in initial part of the pseudo wave field after this transformation. It seems this was result in the numerical inverse Laplace transformation. The oscillation depends on the sampling interval in the approximation.2. I have computed transient vertical magnetic field for layred earth model and its pseudo wave field. The direct wave was detected in the wave field at the time expected from the wave theory. But, the refractive and reflective waves were not clearly detected at expected time because amplitude of these waves are much less than that of direct wave.3. A field test survey was carried out at Yuhuin area, Oita prefecture using the flux gate magnetometer attached with four sensors and the transmitter purchased by the grant. It was clear that this type of instrument was effective to detect the signal and reject of noise. The result was suggested that possibility of noise rejection using signal reference among the data at several sites. The result of survey showed that transient response of vertical magnetic field varied clearly at the Yufuin fault bounded by the Yufuin basin.

研究结果总结如下：1.本文研究了波场的样条逼近。特别注意样条逼近中的项数和采样间隔。在这种变换后，赝波场的初始部分有时会出现一种特殊的振荡。这似乎是数值逆拉普拉斯变换的结果。振荡依赖于近似中的采样间隔.计算了层状地球模型的瞬变垂直磁场及其伪波场。在波场中检测到的直达波的时间从波动理论预期。但是，由于折射波和反射波的振幅远小于直达波的振幅，在预期的时间内没有被清晰地探测到.在大分县的Yuhuin地区，使用附带四个传感器的磁通门磁力仪和赠款购买的发射机进行了现场试验调查。显然，这种仪器对于检测信号和抑制噪声是有效的。研究结果表明，在多个测点的数据中，利用信号参考进行噪声剔除是可行的。测量结果表明，在以汤布院盆地为界的汤布院断层处，垂直磁场的瞬态响应变化明显。