The Electrical Structure of Volcano Aso.

1986年以来，利用Schulumberger垂直测深、VLF-MT、ELF-MT和3分量地磁MT观测对ASO火山进行了电测深研究。研制了观测仪器。1)改进了使用普通录音带的高密度数据采集系统，用于地磁深探（10sec采样）。2)生产了10.2KHz OMEGA VLF MT接收机和3)便携式ELF-MT设备。观察结果如下。4)利用获得的202个观测点的VLF、ELF MT数据，绘制了ASO火山口的三维电阻率图。5) GDS在25个地点发现了九州中部的大型电结构。6) ASO破火山口的电结构分为低阻区（小于50 ω -m）、高阻区（大于500 ω -m）和中间区。7)极低阻带以温泉区和活火山为特征。8)诱导矢量（T>1000sec）在九州中部或北部指向西南方向，而模式计算显示为西南偏南方向。这种差异是由于东海东北部海底存在高导电性物质造成的。

Scince 1986, the study of the electric soundings of ASO Volcano have been conducted by use of Schulumberger vertical sounding, VLF-MT, ELF-MT and 3 component geomagnetic MT observations. Observing instruments were developed.1) High-density data acquisition system, using normal Audio casset tape, was improved for Geomagnetic Deep Sounding (10sec sampling). 2) 10.2KHz OMEGA VLF MT receivers and 3) Portable ELF-MT equipment were produced. Observed results descrived below. 4) 3 Dimensional maps of the electrical resistivities of the ASO Caldera were created using the VLF, ELF MT data obtained 202 observing points. 5) The 25 sites GDS discovered the large scale electrical structures of central KYUSYU. 6) The electric structures of ASO caldera were classified into low resistive zone (less 50 ohm-m), high resistive zone (greater 500 ohm-m) and middle zone. 7) The extremely low resistive zone characterized hot spring areas and active volcanic crater. 8) Whereas induction vector (T>1000sec) point out South-West direction at central or northern part of KYUSYU, model calculations shows SSW. This discrepancy were caused by existence of high conductive materials beneath the North-East part of East China Sea.