Interpretation of long-offset transient electromagnetic data fromMount Merapi, Indonesia, using a three-dimensional optimizationapproach
In the years 1998, 2000, and 2001, long-offset transientelectromagnetic (LOTEM) surveys were carried out at the active volcanoMerapi in Central Java. The measurements investigated the conductivitystructure of the volcanic edifice. Our area of interest, which is belowthe summit and the upper flanks, was investigated using horizontal andvertical magnetic field time derivative data from seventransmitter-receiver setups. Because of topography and athree-dimensional (3-D) underground structure, a 3-D interpretation isused. The method optimizes few parameters of a 3-D model by a stableleast squares joint inversion of the data, providing sufficientresolution capability. Reasonable data fits are achieved with anonhorizontally layered model featuring a very conductive basement belowdepths of 1.5 km. While hydrothermal alteration is also considered, wetentatively explain the high conductivities by aqueous solutions withrelatively high salt contents. A large magma body or a small superficialreservoir below Merapi's central volcanic complex, as discussed by otherauthors, cannot be resolved by the LOTEM data.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE. Assistant Secretary for Energy Efficiency andRenewable Solar and Renewable Resource Technologies
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 926615
- Report Number(s):
- LBNL-63315; R&D Project: G32640; BnR: EB4005010
- Journal Information:
- Journal of Geophysical Research, Vol. 110; Related Information: Journal Publication Date: 2005
- Country of Publication:
- United States
- Language:
- English
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