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MAGNETOTELLURIC MEASUREMENTS ON MILOS, GREECE; (A) A FEASIBILITY STUDY AND (B) GEOTHERMAL EXPLORATION IN AN ACTIVE VOLCANO-TECTONIC ENVIRONMENT.

Objective

A SMALL SCALE STUDY WILL FIRST BE UNDERTAKEN AND IF THE MT METHODS IS FEASIBLE A DENSE ARRAY OF SOUNDINGS WILL FOLLOW AND USED TO PROVIDE ELECTRICAL RESISTIVITY STRUCTURAL MODELS FOR THE UPPERMOST FEW KM. SPECIAL ATTENTION WILL BE PAID TO THE DETECTION OF FAULT ZONES, THE ASSESSMENT OF THE EFFECT OF THE ISLAND LOCATION AND CONSIDERATION OF AN OPTIMUM STRATEGY FOR GEOTHERMAL EXPLORATION.
A series of geophysical research projects was carried out on Milos (Greece) to test and improve the various exploration techniques and strategies on the known geothermal reservoir of the island. 8 research teams from 4 countries (France, United Kingdom, Greece and the Federal Republic of Germany) executed field experiments in joint efforts between 1984 and 1988. Magnetotelluric (MT) methods, audio megnetotelluric (AMT) methods and active audio magnetotelluric (AAMT) methods, electric selfpotential methods and seismological methods were applied to achieve a better understanding of the correspondence of the internal structure and goemetry of the geothermal reservoir with the change of relevant physical parameters.

The experimental phase is over and some of the final reports are available. There is a very close relation between the observed field parameters and the seismic activity with the contours of the geothermal reservoir of Milos.

Following the Travale Testsite experiments (1979 to 1983), the Milos Testsite projects within the Commission's third research and development programme is the second venture of this type. The results are in press as Special Issue of GEOTHERMICS, Pergamon Press.
AT A MEETING IN BRUSSELS IN JUNE 1985, THE ISLAND OF MILOS, GREECE WAS CHOOSEN AS THE LOCATION OF A TEST SITE FOR THE APPLICATION OF GEOPHYSICAL TECHNIQUE FOR THE 3RD EEC GEOTHERMAL PROGRAMME. PRIOR TO THE INCLUSION OF THE MAGNETOTELLURIC (MT) TECHNIQUE AS ONE OF THE GEOPHYSICAL METHODS TO BE DEPLOYED, IT WAS DECIDED THAT A FEASIBILITY STUDY BE UNDERTAKEN TO ESTIMATE THE EXTENT OF "NOISE" CONTAMINATION OF THE MAGNETOTELLURIC RESPONSES ON THIS ISLAND. SUCH CONTAMINATION WAS OBSERVED AT THE TRAVALE TEST SITE, ITALY AND HAS SINCE BEEN FOUND TO A MUCH GREATER EXTENT IN FIELD STUDIES IN OTHER REGIONS OF ITALY AND IN SWITZERLAND. THE SOURCE OF THESE NEAR-FIELD ARTIFICIAL SOURCES IN NOW UNDER ACTIVE STUDY. FOR A STUDY OF THE FEASIBILITY OF THE MT TECHNIQUE ON MILOS, IT IS PROPOSED THAT A SET OF APPROXIMATELY 10 SOUNDINGS BE MADE AT LOCATIONS WHICH COVER A LARGE PORTION OF THE ISLAND. IN THIS WAY, LOCALISATION OF POSSIBLE "NOISE" SOURCES AND ALSO PRELIMINARY INFORMATION RELEVANT TO THE MODELLING OF ISLAND MT DATA SHOULD BE OBTAINED. THE EDINBURGH S.P.A.M. MK II SYSTEM WILL BE USED FOR THE STUDY - THIS IS AN UPDATE OF THE S.P.A.M. MK I SYSTEM USED AT TRAVALE, AND INCORPORATES A FACILITY FOR ID DATA INVERSION IN THE FIELD. THUS WHILE THE PROPOSED SITE DISTRIBUTION IS AS FOLLOWS THIS MAY BE AMENDED ON THE BASIS OF THE IN-FIELD ANALYSIS :

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

University of Edinburgh
Address
Old College South Bridge
EH1 1HN Edinburgh
United Kingdom