ABSTRACT: One-dimensional robust inversion of MT
data applied for interpretation of
CSAMT far-field data in Merapi volcano, Indonesia
Enjang Jaenal Mustopa1,
Supriadi Supriadi2, Doddy
Sutarno3, and
Keisuke Ushijima4
(1) Exploration Geophysics Laboratory Dept. of
Earth Resources System Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku,
Fukuoka, 812-8581, Japan, phone: +81-92-6423643, fax: +81- 92-6423614, [email protected]
(2) Physics Department, Semarang State
University (UNNES), Jl. Raya Sekaran, Gunung Pati, Semarang
(3) Physics
Department, Bandung Institute of Technology, Jl. Gannesha 10, Bandung, 40132
(4)Exploration Geophysics Laboratory, Department of Earth Resources System
Engineering, Kyushu University, Fukuoka, 812-8581, Japan
In the past time, some authors have published papers
about 1-D inversion method
of
Magnetotelluric
(
MT
) data through least-square (LS)
method
.
Ls
method
assumes simple Gaussian statistic. However estimation procedure based on LS
would not be statistically optional, as outliers (abnormal data) are frequently
superimposed on a normal ambient
MT
noise field which is approximately Gaussian. In this
situation can be seriously misleading.
This paper introduces an inversion method
by a robust procedure, which is commonly
based on the least square (LS) approach, by minimizing the separation between observed
data and computed apparent resistivity of the parameter model involved in the inversion
problem. Huber hybrid
method
, one of technique for getting weighting factor, is used in
this robust procedure. The first solution in the iterative
method
involves LS procedure.
Singular Value Decomposition (SVD) is also used in which produces significant improvement
in computational precision. Nevertheless, inversion technique does not result a unique
solution.
This procedure is applied to interpret Controlled Source Audio frequency (CSAMT) far-field data from Merapi volcano which the final result is determination of resistivity upper structure of Merapi Volcano.
AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia