EXPERIMENTAL-STUDY OF A VAN NETWORK IN THE FRENCH ALPS

In 1989, a telluric and magnetotelluric network was installed in the n orthern part of the French Alps by the Laboratoire de Detection et de Geophysique (LDG). The purpose of this experiment was to check the app licability of the Greek VAN method to earthquake prediction in a diffe rent geotectonic and seismic context from the Greek one. The sites wer e selected according to several criteria for geology and potential noi se sources. A complete station consists of six telluric non-polarisabl e dipoles of Petiau type, 2 magnetometers of Mosnier type and an acqui sition unit run by solar energy. The interesting signals are not corre lated with the geomagnetic field variations. Anthropogenic noise, elec trochemical variations and atmospheric storms are not listed. Syntheti c graphs sum up the seismic and telluric activities during 3 months an d 2 weeks. For the correlation between earthquakes and potential tellu ric precursors, we consider first the multiple epicentres, then the ne ar-field ones and finally the most significant events. Some encouragin g results are presented. This experiment must be continued over a long er period and the network completed with low-frequency radio-electric receiving stations.