MT Impedance Estimates at the Kilahuea Volcano Site
Abstract
In 1998 a MT survey was carried out at the Kilahuea volcano site, Hawaii to investigate the electrical structures. High noise levels, insufficient sites and the lack of adequate data processing tools resulted in a very poor quality conductivity interpretation.. In an effort to evaluate the possibility to record good quality MT data, a MT feasibility study was performed at the same site, as a collaborative effort between Lawrence Berkeley National Laboratory, Sandia National Laboratories, Electromagnetic Instruments and the USGS Hawaiian Volcano Observatory. High noise levels where systematically encountered at five different reoccupied sites on the 0.1 to 10 Hz band. The observed low signal to noise ratios are due to abnormal signal levels on the electric components, rather than the expected lack of strength on the natural electromagnetic spectrum on the dead band. As a result, heavily biased MT estimates where obtained when processing the data using traditional least squares stacking, and although the noise on the electric field measurements appears to be incoherent across different stations, the resulting sounding curves are still biased when using a multiple station robust processing technique. This last approach could be tailored by down weighting the electric measurement, which removed the biased and recovered the MT sounding curves.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFMGP51A0987C
- Keywords:
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- 0910 Data processing;
- 0925 Magnetic and electrical methods;
- 1515 Geomagnetic induction