Fault plane solutions of microearthquakes in the Loviisa region in south-eastern Finland

摘要

Fifteen microearthquakes have been recorded by a small seismic network in the Loviisa area from 1985 to 1988. Fault plane solutions of these events based on spectral amplitudes and polarities of vertical first motions are presented. In addition, multievent locations have been performed to define the geometry of the seismically active block boundaries. The study also deals with the possibilities to use modern data acquisition and analysis techniques as a tool for measuring slow block movements of the bedrock. The results are discussed with the framework of the previous seismic and seismotectonic interpretations obtained by more conventional methods. The small number of seismic stations available prevents in many cases definite conclusions. The seismic network only consisted of three stations. The seismic events were clustered in five source areas. In these areas, the most probable fault geometries and mechanisms associated with the seismic observations are presented. (29 refs.). (Atomindex citation 28:007510)