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Abstract

Monitoring the natural seismicity of Milos Island over a four month period has led to the conclusion that the microseismic activity is concentrated mainly in the central-eastern part of the island in the depth range from 5-8km. Tomographic inversion of 90 selected events has led to a refined velocity-depth distribution. The fluctuation of velocities appears to be depth-dependent; a remarkable horizontal change of velocities is found for the upper few kilometers of the crust, while at greater depth the crystal velocity is more homogeneous. Minima of the v(p)/v(s) ratio coincide with the locations of the production wells in the Zefyria Plain and close to Adamas, thus indicating higher temperatures in these areas. Faultplane solutions indicate that tensional stress in a NE-SW direction is the actual cause of the seismic activity. The frequency-magnitude relation indicates tectonic activities rather than volcanic. The polarisations of the leading shear-waves show alignments which in general are consistent at each station and at groups of stations. The crack distribution probably exists within only a few kilometers from the surface.

Additional information

Authors: WOHLENBERG J, RWTH Aachen (DE);OCHMANN N, RWTH Aachen (DE);HOLLNACK D, RWTH Aachen (DE);SCHLEPER S, RWTH Aachen (DE)
Bibliographic Reference: EUR 12450 DE (1990) 124 pp., MF, ECU 8
Availability: (2)
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