Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-12-02T00:39:01Z No. of bitstreams: 1 EduardoAlexandreSantosDeMenezes_DISSERT.pdf: 3118703 bytes, checksum: f207d47849b604d3418533d85348bd7e (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-12-06T20:37:45Z (GMT) No. of bitstreams: 1 EduardoAlexandreSantosDeMenezes_DISSERT.pdf: 3118703 bytes, checksum: f207d47849b604d3418533d85348bd7e (MD5) / Made available in DSpace on 2017-12-06T20:37:45Z (GMT). No. of bitstreams: 1 EduardoAlexandreSantosDeMenezes_DISSERT.pdf: 3118703 bytes, checksum: f207d47849b604d3418533d85348bd7e (MD5) Previous issue date: 2017-08-18 / A regi?o s?smica estudada se localiza no munic?pio de Irau?uba, Cear? (CE), localizado na Prov?ncia Borborema, sendo uma das regi?es mais sismicamente ativas do Brasil. A atividade s?smica do Nordeste do Brasil ? bastante observada devido a muitos eventos que ocorreram na regi?o por v?rios anos, com repeti??es em algumas ?reas, que s?o conhecidas como ?reas ativas. Muitos destes eventos s?o percebidos pelas popula??es das ?reas onde ocorrem, pois apesar deles n?o atingirem grandes magnitudes, chegam a assustar a popula??o. Em alguns casos at? acarretam pequenos danos em casas, tais como pequenas trincas nas paredes e deslocamento de telhas. Um desses exemplos desta atividade s?smica ? a que ocorre na cidade de Irau?uba, localizada na por??o Noroeste do estado do Cear?, a 175 km de sua capital, Fortaleza. A atividade s?smica em Irau?uba ? conhecida e estudada desde 1991, onde ocorreram v?rios tremores ao sul, na localidade de Ju?, distrito de Irau?uba. Nesta regi?o, o maior tremor atingiu 4,9 mb, s? superada no Cear? pelo tremor de Pacajus de 1980 (5.2 mb). Uma nova intensa atividade s?smica iniciou-se em 9 de setembro de 2015, e perdurou at? o in?cio de mar?o de 2016, quando foram registrados mais de 500 tremores. Desta vez, o maior de intensidade observada foi de IV (MM), com a magnitude m?xima observada de 3,8 mb. Este trabalho ? decorrente da an?lise dos dados coletados na campanha realizada no per?odo de setembro de 2015 at? o in?cio de mar?o de 2016. Nesta campanha, foram utilizadas sete esta??es sismogr?ficas digitais, sendo seis compostas por aceler?grafos a tr?s componentes e uma esta??o, com um conjunto de tr?s sism?metros de per?odo curto (um vertical e dois horizontais). Os dados registrados por elas foram analisados, objetivando a determina??o de hipocentros e dos mecanismos focais. Foram analisados 294 eventos s?smicos, registrados em pelo menos quatro esta??es, utilizando o programa COMPASS. Na determina??o hipocentral, foi utilizado o programa HYPO71, utilizando-se um modelo de semiespa?o, com os seguintes par?metros: velocidade de onda P (Vp) de 6,20 km/s e raz?o Vp/Vs de 1.69. Todos os eventos detectados em pelo menos quatro esta??es, com res?duo de tempo menor que 0,01 s e erros horizontais e verticais menores que 0,01 km, num total de 69 eventos, possuem um alinhamento N-NW e revelam uma zona ativa de aproximadamente 2 km de extens?o e profundidade variando de 8 a 9 km. Dentre os 69 eventos selecionados foram escolhidos 22 mais bem localizados para determina??o do plano de falha a partir dos hipocentros, obtendo-se os valores do mecanismo focal composto, realizado com aux?lio do programa FPFIT. Os par?metros da falha sismog?nica foram obtidos pela combina??o do m?todo dos m?nimos quadrados e do programa FPFIT (dire??o = 45?, mergulho = 52? e o rejeito total = -151?), confirmando a orienta??o da falha na dire??o NNW-SSE, com movimento normal. Os epicentros e o mecanismo focal n?o parecem indicar que haja correla??o com estruturas mapeadas at? agora em superf?cie. / The studied region is located in the municipality of Irau?uba, Cear?, in the Borborema Province and it is one of the most active seismic regions of Brazil. The seismic activity of the Northeast of Brazil is well observed by several events that have occurred in the region for many years, with repetitions in some areas that are known as active areas. Many of these events are perceived by population of the areas where they occur, because even if these events do not reach great magnitudes, they may frighten natives. In some cases, they even cause small damages in houses such as small cracks in the walls and displacement of tiles. One example of this kind of seismic activity is the one that occurs in the Irau?uba city, located in the northwestern portion of the Cear? state, 175 km from its capital, Fortaleza. The seismic activity in Irau?uba is known and studied since 1991, when several tremors occurred in the south, in the Ju? city, district of Irau?uba. In this region, the biggest tremor reached 4.9 mb of magnitude, surpassed only in Cear? by the tremor in Pacajus in 1980 (5.2 mb). A new intense seismic activity began in September 9, 2015, and it lasted until the beginning of March, 2016, when more than 500 tremors were registered, but this time the highest intensity IV (MM) was observed, with maximum observed magnitude of 3.8 Mb for this period. This master thesis deals with the analysis of collected data in the performed campaign in the period from October, 2015 to the beginning of March, 2016. In this campaign, seven digital seismographic stations were used, of which six were composed of accelerometers in three components, and one was composed of a set of three short period seismometers (one vertical and two horizontal). The data recorded by these stations were analyzed, with the objective of the determination of hypocenters and focal mechanisms. 294 seismic events were analyzed, recorded by at least four stations, using the Compass software. In the determination, the HYPO71 software was used to determine the hypocenters, using a semi-space model with the following parameters: P wave velocity (Vp) of 6.20 km/s and Vp/Vs ratio of 1.69. All events were detected at least by four stations, with time residue less than 0.01 s and horizontal and vertical errors less than 0.1 km. A total of 69 events have a N-NW alignment and revealed an active zone of approximately 2 km of extension and depth varying from 8 to 9 km. For a set of 23 tremors more well located, a fault plan was determined from the hypocenters, and values of a composite focal mechanism were obtained, performed with the aid of the FPFIT software. It was done for a set of data, fixing the fault plan. The parameters of the seismogenic fault were obtained by the combination of the least squares method and the FPFIT software (strike = 45?, dip = 52? e o rake = -151?), confirming the orientation of the fault in the direction N-NW, with normal movement. The epicenters and the focal mechanism do not seem to indicate that there is correlation with so far mapped structures in surface.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-20T22:47:57Z No. of bitstreams: 1 CristianeDeSouzaCosta_DISSERT.pdf: 4024324 bytes, checksum: 8f3dfa5b801aa9e83961b2b314e444fe (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-02-24T20:17:07Z (GMT) No. of bitstreams: 1 CristianeDeSouzaCosta_DISSERT.pdf: 4024324 bytes, checksum: 8f3dfa5b801aa9e83961b2b314e444fe (MD5) / Made available in DSpace on 2017-02-24T20:17:07Z (GMT). No. of bitstreams: 1 CristianeDeSouzaCosta_DISSERT.pdf: 4024324 bytes, checksum: 8f3dfa5b801aa9e83961b2b314e444fe (MD5) Previous issue date: 2016-08-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A atividade s?smica em Pedra Preta-RN teve in?cio em dezembro de 2010. Antes disso, n?o havia registro de sismos nesta ?rea, localizada no nordeste brasileiro, onde ? registrada a maior sismicidade intraplaca do Brasil. Durante o ano de 2013 e in?cio de 2014, a rede sismogr?fica de Pedra Preta-RN registrou 273 sismos locais em tr?s ou mais esta??es. Todo o conjunto de dados foi analisado no software COMPASS. Atrav?s do diagrama Wadati, foram selecionados os 50 eventos com melhores leituras dos tempos de chegada das ondas s?smicas P e S. Com o aux?lio do programa HYPO71 foi determinado o modelo de velocidades (Vp/Vs =1,72 e Vp = 5,90 km/s) e calculados os hipocentros. Para a determina??o do mecanismo focal composto, realizou-se uma nova sele??o de sismos obedecendo crit?rios mais restritos para os hipocentros (Gap < 180, RMS ? 0,01 s, N? de observa??es ? 10, ERH < 0,1 Km, ERZ < 0,1 Km), selecionando 24 eventos. Os hipocentros destes sismos mostram que a falha sismog?nica tem aproximadamente 3 km de extens?o, com sismos entre 2,3 a 5,8 km de profundidade. Os par?metros da falha sismog?nica foram obtidos pela combina??o do m?todo dos m?nimos quadrados e do programa FPFIT (strike = 254?, dip = 67? e o rake = -66?), caracterizando uma falha normal. Os epicentros e o mecanismo focal foram utilizados para verificar se havia ou n?o poss?veis correla??es com fei??es geol?gicas mapeadas na ?rea de estudo. A conclus?o ? que n?o existem fei??es geol?gicas mapeadas que possam estar relacionadas diretamente com a atividade s?smica estudada. / The seismic activity in Preta Pedra-RN began in December 2010. Before that, there was no record earthquakes in this area, located in the Brazilian Northeast, where is recorded the largest intraplate seismicity of Brazil. During 2013 and early 2014, the seismographic network Pedra Preta registered 273 local earthquakes in three or more stations. The entire data set of this work was analyzed in the COMPASS software. By Wadati diagram were selected 50 events with the best readings from the arrival times of P and S waves. With the help of HYPO71 program, was determined the velocity model (Vp / Vs = 1,72 and Vp = 5.90 km/s) and calculated the hypocenters. For the determination of the composed focal mechanism, these was a new selection of earthquakes obeying more stringent criteria for the hypocenters (Gap <180, RMS ? 0.01 s, Number of observations ? 10, ERH <0.1 km, ERZ <0, 1 Km), selecting 24 events. The hypocenters of earthquakes show that the seismogenic fault is about 3 km long, with earthquakes between 2.3 to 5.8 kilometers deep. The parameters of seimogenic fault were obtained by combining the method of least squares and FPFIT program (strike = 254?, dip = 67? and the rake = -66?), indicating a normal fault. The epicenters and focal mechanism were used to verify whether there was possible correlations with geological features mapped in the study area. The conclusion is that there are no mapped geological features that may be directly related to the seismic activity studied.