METHOD FOR SEARCHING UNDERGROUND STRUCTURE BY ELECTROMAGNETIC WAVE

摘要

PURPOSE:To more accurately determine an underground structure, by measuring the specific resistances up to several ms - several kms and the dielectric constants up to several ten ms in the ground by utilizing an electromagnetic wave of 7Hz - 1MHz. CONSTITUTION:An artificial oscillator 1 oscillates an electromagnetic wave of 7Hz - 1MHz and the AC of a single-phase generator 2 is boosted by a boosting transformer 3 and converted to DC by the rectifier in an oscillator main body 4. Each frequency is formed by cutting said DC by switching and a current is allowed to flow to the ground using a copper electrode 6. A receiver 7 is arranged so that electrodes 11 are respectively separated and a coil 10 for a magnetic field sensor is set so as to cross the receiver 7 at a right angle. The original wave form of a receiving wave is outputted as an effective value from the wide band of an MT (magnetotelluric) meter main body 9 and the wave form of selected frequency is outputted as an effective value from a narrow band. An oscilloscope 8 takes the wave forms of both components in a portable computer 12 from the terminal of the narrow band of the receiver 7 to measure specific resistances up to several ms - several kms and dielectric constants up to several ten m in the ground and an underground structure is elucidated.