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An operation test of EM-ACROSS (Accurately Controlled Routinely Operated Signal System with an artificial electromagnetic source) has been carried out by Tono Geoscience Center, Japan Nuclear Cycle Development Institute, toward an electromagnetic active monitoring of the crustal structure and dynamics at Tokai area, Japan. The purpose of this experiment is to develop the system and evaluate the performance of the EM-ACROSS equipments. Through this experiment, we intend to understand the propagation feature of the EM-ACROSS signals, and to obtain transfer functions having high signal-to-noise ratios (SNR) suppressing natural and artificial noise and eliminate human errors. An electromagnetic signal that consists of a set of sinusoidal components is transmitted with current dipoles of 100m installed at Tono mine, and the electric and magnetic fields have been observed at five observatories at distances from 1 to 50km from the source. The received signals are stacked with an optimum weighted stacking method in order to increase the SNR as much as possible. In this operation experiment, the EM-ACROSS signals at ~1Hz are detected at the observatory 40km away from the source with SNR larger than 2 by 30days stacking. The source and the three nearest receivers are located in the Toki Granite formation, and the resistivity of the formation is estimated to be ~100Ohm-m assuming a two-layered half-space model for the underground electrical conductivity structure.
Note. Abstracts are published in author's edition
Last update: 06-Jul-2012 (11:44:54)