HR: 11:50h
AN: GP32A-07    [Abstracts]
TI: Modification of three-dimensional magnetotelluric inversion WSINV3DMT to be applied to seafloor
AU: * Tada, N
EM: noriko@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Siripunvaraporn, W
EM: wsiripun@yahoo.com
AF: Department of Physics, Faculty of Science, Mahidol University, Rama 6 Rd., Rachatawee, Bangkok, 10400, Thailand
AU: Uyeshima, M
EM: uyeshima@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Baba, K
EM: kbaba@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Utada, H
EM: utada@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AB: In recent years, a number of seafloor electromagnetic (EM) experiments have been carried out by using Ocean Bottom Electromagnetometers (OBEMs). The density of marine Magnetotelluric (MT) data has been increasing so that imaging electrical conductivity structures under the seafloor in three dimensions is now feasible. WSINV3DMT (Siripunvaraporn et al., 2005) is known as a full three-dimension inversion code for land MT data, and is based on the data space approach. We try to modify this code so as to be able to invert marine MT data, by including bathymetry features and extending locations of observation sites (the output points) allowing on the seafloor as well as the Earthfs surface. As shown in a separate presentation by Utada et al. (2007, in this meeting), we deployed OBEMs in a two-dimensional array in the Philippine Sea. The aim of this code modification is to apply the modified code to the data set from this array experiment to image three-dimensional conductivity distribution in the deep mantle below. The accuracies of the forward modeling part in the modified WSINV3DMT have been verified with one- dimensional resistivity structures. Relative differences between of the MT impedances estimated by the modified WSINV3DMT and those analytically calculated for horizontal layered structures are all below 1%. It was also found that these differences depend on frequency. In this presentation, we will show the accuracy and reproducibility of the modified WSINV3DMT by using synthetic data for three-dimensional resistivity structures.
DE: 0560 Numerical solutions (4255)
DE: 0925 Magnetic and electrical methods (5109)
DE: 1515 Geomagnetic induction
DE: 3006 Marine electromagnetics
DE: 3060 Subduction zone processes (1031, 3613, 8170, 8413)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting