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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:54 |
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Conference: Bucharest University Faculty of Physics 2009 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
A possible deep lithospheric root beneath the Sinaia area
Authors:
C. Neagoe, M. Popa, M. Radulian
Affiliation:
National Institute for Earth Physics
E-mail
cristian.neagoe@infp.ro
Keywords:
earthquake, Sinaia zone, seimicity
Abstract:
The intense intermediate-deep seismic activity in the Vrancea region reflects significant geodynamic processes at the continental contact between East-European, Moesian and Intra-Alpine plates. It is expected that these processes influence also in some way the adjacent seismogenic areas (Ramnicu Sarat, Sinaia, Fagaras-Campulung). This study focuses on a particular aspect of the Sinaia zone seismicity. Usually, the earthquakes are generated in the crustal domain, sometimes in sequences (a noteworthy case is the sequence of May-June 1993 with 318 identified events). However, sporadically there were reported isolated events at subcrustal depths (below 60 km). A recent earthquake of local magnitude 2.9 was recorded on May 8, 2009 at a depth of 95 km. The event was recorded by 17 stations of the Romania Seismic Network. Considering the number of P and S wave phases and the station distribution, the earthquake location is well constrained. Similar events have been reported in the past: 01.05.1974 (h=90km; MD=2.7); 14.03.1981 (h=100km; MD=3.1); 26.03.1984 (h=71km; MD=3.2); 01.02.1985 (h=59km; MD=3.6); 17.01.1986 (h=71km; MD=2.3). The focal mechanism for the event of May, 2009 is a typical reverse faulting and close to the predominant fault plane solutions of the Vrancea intermediate-depth source. The analysis of the waveforms suggests a complicated structure beneath the study region. Conversion phases are identified at the most of the stations. According to our interpretation this subcrustal activity emphasizes the presence of a high velocity material beneath Sinaia region which is in agreement also with the last tomography studies (Martin et al., 2005, Zaharia et al., 2009).
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