Experimental study of a VAN network in the French Alps.

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Propagation of regional seismic phases in Western Europe

Rapport RADIOMANA Paris (France) contracts AFOSR-87-0331, PL*TR-91-2064, XFTR-91-2064,15 juillet 1987-14 juillet 1990, 77 ppThis report describes the main results achieve during the period July 1987 thru July 1990 for the following researches. - Propagation of regional phases in Western Europe.- Determination of QLg and Q coda in the I to 15 Hz frequency band. Geographical variations of Q are strongly correlated to the tectonical features and to other geophysical anomalies. This result correspond to the attenuation of Lg phases propagating through the positive Bouguer anomaly in the Western Alp. Those variations* in Q were, not only observed, but also modelized. - Far field effects due to the structure near the joint sources: numerical computations show variation of mb up to 0.25 at teleseismic distances induced by variations in the shape of the basement beneath a seismic event. - Source evalu:ition at teleseismic distance: we observed limitations in the relative magnitude determination of Eastern Kazakh events in using the French Seismic Ne-rwork. The source functions computed with this network are definitively differentfor events originating in the NE or in the SW of Shagan River

Detection of underwater explosion at very long-range

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