Foreword. 9This report consists of three papers. The data used are mainly surface wave recordinqs from the VLP -station in Yonasbera, Norway. This station is one of the 10 broad band hiqh qain installations presently in operation throughout the World. -i9 2 PART I PHASE REVERSAL AND TIME DELAY OF EXPLOSION-GENERATED SURFACE WAVES. EIVIND RYC ABSTRACT A phase shift of 1800 has been found between the Rayleigh wave trains of two closely located Eastern Kazakh explosions The Rayleigh waves from one

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... of the explosions were delayed by about 4 sec relative to the Rayleigh waves from the other explosion. The event generating the delayed Rayleigh waves excited relatively strong Love waves, but these waves were not delayed. Various causes for the anomalies have been discussed -explosion-collapse pairs -depth differences and spallation. It seems that the Love waves of the anomalous event have been generated very near the source at the time of the detonation while the Rayleigh waves have been generated by a secondary event, -collapse-or by spall] closure above the explosion. I KONGSBERG VLP-SYSTEM SVEIN VAAGE and EIVIND RYGG ABSTRACT Epicenter locaticons 1bave been estimated for a number of unidentified events using the VLP-recordings of Kongsberg, Ncrway. The epicenters grouped along the active seismic zones of the Mid Atlantic ridge. Events north of Iceland radiated very weak Love waves compared to the Rayleigh. waves.