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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:56 |
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Conference: Bucharest University Faculty of Physics 2010 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Receiver function studies in Romania
Authors:
D. Tataru, B. Grecu, V. Raileanu
Affiliation:
National Institute for Earth Physics, Magurele, Romania
E-mail
dragos@infp.ro
Keywords:
receiver function, joint inversion, lithosphere
Abstract:
We follow previous approaches and develop velocity models for the study area using the joint inversion of surface-wave dispersion and receiver functions. Data were recorded by permanent broadband seismic stations of Romanian Seismic Network. Teleseismic receiver functions have been used to provide constraints on crust and upper-mantle shear-wave structure, but the resulting models are nonunique as they contain little absolute velocity information (Ammon et al., 1990). The inability to constrain absolute velocity leads to trade-offs between velocity and depth and results in a range of final velocity models with different average velocities that fit the observed receiver functions equally well. Özalaybey et al. (1997) addressed this nonuniqueness by proposing the joint inversion of receiver functions and surface-wave velocities. More then 300 high signal-to-noise ratio teleseismic events with great circle epicentral distances of 30°–95° and magnitudes above 5.5, occurring between 2004 and 2009 were chosen for analysis. The inversion results show a thin crust for stations located inside the Pannonian basin (28-30 km) and a thicker crust for those in the East European Platform (36-40 km). The stations within the Southern and Central Carpathian Orogen are characterized by crustal depths of ~35 km. For a station located in the Apuseni Mountains the Moho discontinuity is replace by a transition zone extended between 36 to 40 km depth, and for those located in the Carpathians bent area we identify a double Moho (32 respectively 44 km depth) possible due to the Vrancea subduction process. For the crust of Moesian Platform we get higher values (~35 km) compare to those obtained from seismic refraction profile (VRANCEA’2001). The North Dobrogea crust reaches a thickness of about 44-46 km. For most of the stations the crust-mantle transition zone has a significant gradient, with velocity values varying from 3.8 to 4.7 km/s.
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