Banca de QUALIFICAÇÃO: JOSÉ AUGUSTO SILVA DA FONSÊCA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSÉ AUGUSTO SILVA DA FONSÊCA
DATE: 29/07/2022
TIME: 10:00
LOCAL: videoconferência https://www.youtube.com/channel/UCCBwJxTIfyeGmQSqDLK6duw
TITLE:

Probabilistic Seismic Hazard Analysis for NE Brazil

KEY WORDS:

Probabilistic Seismic Hazard Analysis; Seismic zonation; Intraplate seismicity; NE Brazil

PAGES: 25
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

NE Brazil has experienced remarkable strain events along its geologic history with large paleoearthquakes (~5.5- 6.0 Mw), commonly separated by quiescent periods of few tens ka. Documented low to moderate seismicity data dates back to a few centuries ago, and the low seismic attenuation means that even moderate-magnitude earthquakes (~ 4.0-5.0 mb) may pose a significant hazard. Besides, increasing population and proximity to seismic sources means that even smaller seismic events generate societal inconvenience (“nuisance” seismic events). In this regard, assessing the damaging seismic occurrence potential to society is of considerable importance, and, to this end, we report our preliminary results from a Probabilistic Seismic Hazard Analysis (PSHA) over this region. For this purpose, we filtered the original seismic catalog using epicentral uncertainty, magnitude completeness, and seismicity declustering (to accomplish temporal independence of earthquakes PSHA premise). The Chi-square test performed over the remaining catalog indicates that Poisson distribution cannot be rejected, thus accomplishing temporal independence of earthquakes PSHA premise. Then, seismic zonation was performed following expert judgment alongside a 1º sliding window with 25 km- radius kernel-density estimations, resulting in 4 seismic zones where epicenter density is the greatest. The other three seismic zones were delimited, considering regions whose magnitude and intensity have been able to cause a minimum nuisance to the population. Additionally, we outlined a background source seismicity to comprise a region with significant magnitude earthquakes (typically greater than 3.0 mb) but without a clear spatial clustering. As a result, assuming a fixed bvalue = 0.92 for all seismic zones and adopting backbone Ground Motion Prediction Equations from other intraplate areas with similar tectonic conditions, we were able to carry out hazard calculations using the R-CRISIS program. Our preliminary results display maximum PGA values of 5-8% g for a 10% probability of exceedance in 50 years.

COMMITTEE MEMBERS:
Presidente - 1451214 - ADERSON FARIAS DO NASCIMENTO
Externo ao Programa - 346467 - JOAQUIM MENDES FERREIRA - UFRNExterno ao Programa - 1217836 - PETRUS GORGONIO BULHOES DA NOBREGA - UFRNExterno à Instituição - PAULO DE SOUZA TAVARES MIRANDA - IFCE