UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-21 20:12
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Conference: Bucharest University Faculty of Physics 2008 Meeting


Section: Atmosphere and Earth Science; Environment Protection


Title:
Receiver functions technique - a new tool for investigation of the Romanian crust


Authors:
D. Tataru, V. Raileanu


Affiliation:
National Institute for Earth Physics, Magurele, Romania


E-mail
dragos@infp.ro


Keywords:
receiver function, crust, Moho


Abstract:
Recently new studies on the crustal structure where achieved in our institute based on the receiver function method (RF) applied to teleseismic events recorded in a few broad band stations. It was used the teleseismic events in order to analyze the P-to-S conversion at the Moho (Ps) and their reverberating phases in the crust. The pre-processing of the teleseismic waveform and the calculation of the RFs is done according to an algorithm of Yuan et al. 1997. After some processing steps the seismometer components Z, N–S and E–W are rotated into the ray coordinate system L, Q and T using the theoretical BAZ and ray parameter of the events. The subsequent deconvolution of the Q component with the P wavelet on the L component removes the source function from the converted arrivals, and thus the RFs for different events at a single station become comparable and can be summed to increase the signal-to-noise ratio. Before stacking of more events a distance-dependent moveout correction to an average distance of 67◦ is applied.A visual inspection of the waveforms is done to sort out noisy traces or traces with disturbances in front of the P-wave arrival, before accepting the final radial RFs. The final P receiver function contains, besides the primary converted phases, the multiple phases generated by each velocity discontinuity and reflected waves between the earth`s surface and these discontinuities. The interpretation of the obtained Ps phases indicates depths to the Moho boundary at 35 km (VRI), 33 km(TIRR) and 22 km (DRGR). In all three representations the conversion phases from the sediment to basement boundary for the earthquakes with epicentral distances less then 300 appear at around 0.5 s delay time, they being clear visible and indicating a negative velocity contrast.