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Source Effects of Vrancea Earthquakes vs. Site Effects Recorded in Bucharest City, Romania
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 8th Congress of the Balkan Geophysical Society, Oct 2015, Volume 2015, p.1 - 5
Abstract
Different studies focused on the Vrancea subcrustal source of earthquakes pointed out the strong lateral inhomogeneous distribution of the seismic radiation. This implies characteristic macroseismic distributions, extremely elongated along NE-SW direction, and sharply restraint toward NW and SE. The fault plane solutions of most Vrancea earthquakes indicate a nearly pure thrust mechanism with the B-axis striking NE, which is typical for the strongest events. We analyze the influence of focal mechanism radiation on the ground motion parameters in Bucharest area.
The analysis of a recent set of intermediate depth earthquakes with Mw > 4.5, for which the focal mechanism have been computed, show the significant role played by the variation of these parameters in respect to the seismic motion recorded. These parameters might be as important as the site effects in establishing the local seismic hazard for the Bucharest City.
The role of the focal mechanism of the earthquakes and of the depth at which the earthquakes occur determine the path on which seismic waves are propagating to the surface. A significant role is played by the variation of the lithosphere structure between the depth of earthquakes and the surface, for the seismic motion recorded in the Bucharest area.