HR: 16:45h
AN: NS34A-04 INVITED    [Abstracts]
TI: Advances in Grounded Electrical Source Airborn Transent EM(GREATEM) system
AU: * Mogi, T
EM: mogitisv@mail.sci.hokudai.ac.jp
AF: Hokkaido University, N10W8, Kita-ku, Sapporo, 060-0810, Japan
AU: Group, G R
EM: mogitisv@mail.sci.hokudai.ac.jp
AB: One of the important techniques to challenge on AEM survey is increasing penetration depth to apply for mineral explorations, environmental and disaster prevention issues. AEM systems usually carry a source and a receiver on the airplane and a size of source and/or a source-receiver distance are limited. We have developed the GREATEM system which uses long electric wire source on the ground and measure the induced field in the air at distance to guarantee deeper penetration depth. The penetration depth of the survey depends on how to gain long transient curves in time domain acquisition. We installed high performance magnetometer, A/D converter to obtain full wave of 3 components data and high accuracy fiber optic gyros to monitor motion of the sensor in the bird. We made a motion correction of observed magnetic field using a transformation between measured motion and variation of magnetic field for lower frequency perturbation. Unsteady state noises were suppressed by appropriate filter to delineate the transient curve at later time. We carried out the survey in Aso Volcano in southwest Japan to detect distribution of potential landslide area in an alteration zone and a water reservoir controlling phreatic eruption. The resistivity structures up to 1000m were detected in this survey under suitable conditions.
DE: 0600 ELECTROMAGNETICS
DE: 0900 EXPLORATION GEOPHYSICS
SC: Near-Surface Geophysics [NS]
MN: 2007 Fall Meeting