| Texto completo | |
| Autor(es): |
Dicelis, Gabriel
;
Assumpcao, Marcelo
;
Prado, Renato Luiz
;
Agurto-Detzel, Hans
;
Barbosa, Jose Roberto
Número total de Autores: 5
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Geophysical Journal International; v. 210, n. 2, p. 594-608, AUG 2017. |
| Citações Web of Science: | 1 |
| Resumo | |
We investigate a long series of small earthquakes (magnitude < 3) with annual cycles between 2004 and 2010 that occurred in the northeastern Parana Basin, Brazil. These events were attributed to pore pressure increase in a fractured aquifer caused by the drilling of several water wells down to depths of similar to 200 m. Because of the poor depth constraints of the initial study, we relocated similar to 1000 microtremors recorded by the local seismographic network using a more accurate velocity model. To better relocate the events, we based the velocity model on geophysical survey data obtained using several techniques, including seismic refraction, surface wave dispersion, vertical electrical sounding, high-frequency receiver functions and the time-domain electromagnetic method. The best 1-D model was calibrated using a simultaneous inversion of hypocentres and a velocity model including station corrections. The resulting focal depths, which are mostly between 100 and 175 m, place the events at depths consistent with the confined aquifer within the basaltic pack. This result confirms that the earthquakes are related to geological stress disturbances (pore pressures) in pre-existing fracture zones within the basalt layer caused by the perforation of water wells used for irrigation. We used a combination of cross-correlations and arrival times to analyse a cluster of 19 earthquakes. The improved hypocentre distribution of this cluster allowed the determination of a clear fault-plane solution, which indicates a normal fault striking WNW-ESE and dipping to the north, with an NNE-SSW extension (T-axis). This mechanism complements stress data collected in southeastern Brazil and is consistent with the regional stress regime. (AU) | |
| Processo FAPESP: | 14/09455-3 - Sismos induzidos em Bebedouro, SE Brasil: sismicidade, estrutura de velocidade e mecanismos focais |
| Beneficiário: | Hans Alex Agurto Detzel |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 07/04325-0 - Tremores de terra em Bebedouro-SP, induzidos por poços tubulares: evolução da atividade e causas estruturais |
| Beneficiário: | Marcelo Sousa de Assumpção |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |