Banca de QUALIFICAÇÃO: JOSÉ RICHARLES ALMEIDA GOMES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSÉ RICHARLES ALMEIDA GOMES
DATE: 20/12/2022
TIME: 10:00
LOCAL: videoconferência https://www.youtube.com/c/PPGGUFRNTransmiss%C3%A3odeBancas
TITLE:

Determining crustal thickness in the Brazilian Shield with vertical receiver functions

KEY WORDS:

Autocorrelation Functions; Crustal thickness; Brazilian Shield.

PAGES: 20
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

Receiver functions (RFs) are one of the most traditional approaches for investigating crustal and upper mantle  structure worldwide. This methodology consists of deconvolving the vertical component from the corresponding  radial component in teleseismic recordings to obtain the structural response of the subsurface close to the receiver.  In this approach, the time series thus obtained are composed of Ps conversions and their reverberations, making  RFs sensitive to S-wave velocity in the propagating medium. In recent years, the feasibility of using auto correlation functions (ACFs) of teleseismic recordings to obtain similar but complementary results to those from  RF analysis has been demonstrated. In the case of radial ACFs, the result can still be interpreted as a combination of Ps conversions and reverberations, as with traditional RFs, but with the addition of a P-wave reverberation that  is usually missing in traditional RFs. This reverberation is even more apparent in the vertical ACFs, providing complementary information on the P-wave velocity structure of the propagating medium. One of the  implementations of this new approach includes a spectral division during data processing that makes ACFs and  RFs analogous. In this case, the vertical ACF is known as the vertical receiver function (VRF). In this work, VRFs  are calculated using data from broadband seismic stations making up the Brazilian Seismographic Network  (RSBR). Our objective is to compare and expand estimates of crustal thickness and average crustal velocity  obtained in previous studies with traditional RFs for the stable portion of the South American continent.  Preliminary estimates with VRFs are close to those obtained with traditional RFs, in general. We hypothesize that  differences in crustal thickness estimates are related to either inadequate P-velocity assumptions during traditional  RF analysis or to a gradational crust-mantle boundary under the recording station Moho. Future research will include more integrated estimates of crustal properties through the H−κ−VP−Stacking method and the performance  of numerical experiments to investigate inconsistencies between crustal thickness estimates.

COMMITTEE MEMBERS:
Externo à Instituição - MARTIN SCHIMMEL - CSIC
Interno - 1451214 - ADERSON FARIAS DO NASCIMENTO
Externo à Instituição - CARLOS ALBERTO MORENO CHAVES - USP
Presidente - 1863578 - JORDI JULIA CASAS
Externo à Instituição - MARCELO SOUSA DE ASSUMPÇÃO - USP