Banca de DEFESA: MARIA RAYLA DOS SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARIA RAYLA DOS SANTOS
DATE: 14/07/2026
TIME: 09:00
LOCAL: Videoconferência
TITLE:

SOUTH ATLANTIC SEISMOTECTONICS USING TELESEISMIC P-WAVE AND WATER REVERBERATIONS

KEY WORDS:

Focal depth estimation; Water column reverberations; Mid-Atlantic Ridge.

PAGES: 71
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geofísica
SPECIALTY: Geofísica Aplicada
SUMMARY:

Oceanic transform faults are important tectonic structures that connect mid-ocean ridge segments and accommodate relative plate motion. In this context, focal depth (Z) is a key parameter for characterizing the seismogenic zone. However, in remote oceanic environments, source parameter estimates remain a challenge due to the sparse distribution of stations and simplified velocity models. In addition, the limited global teleseismic coverage complicates depth-phase identification, as well as by low signal-to-noise ratios, rupture duration, and focal depth itself. As an alternative, the methodology proposed by Huang et al. (2015) was implemented, which incorporates water-column reverberations to simultaneously determine Z and water layer thickness (H) in the St. Paul Transform System (Transform A), using stacked seismograms at teleseismic distances. Synthetic tests demonstrate stable performance, including under high noise levels, although ambiguities remais in shallow-water settings. The analyzed events (5.7-6.6 Mw) presented Z estimates ranging from 4.4 to 15.3 km, with shallower values than reported in global catalogs, while strike-slip focal mechanisms derived from catalog solutions reflect the dominant tectonic regime of the region. A decreasing trend in Z toward the St. Peter and St. Paul Archipelago was also observed, suggesting structural heterogeneity along the system. H values (1.0-3.5 km) are consistent with regional bathymetry, although instability was observed in one of the cases related to overlapping reverberations. Thus, the results highlight the Z-H analysis as a robust approach for combined estimation of these parameters, emphasizing the sensitivity of the method to local structural complexity.

COMMITTEE MEMBERS:
Presidente - 1451214 - ADERSON FARIAS DO NASCIMENTO
Interna - 2218779 - HELENICE VITAL
Externa à Instituição - CÍNTIA ROCHA DA TRINDADE
Externo à Instituição - JOSÉ AUGUSTO SILVA DA FONSÊCA
Externa à Instituição - ROSANA MARIA DO NASCIMENTO