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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

TDEM survey in an area of seismicity induced by water wells in Parana sedimentary basin, Northern Sao Paulo State, Brazil

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Porsani, Jorge Luis [1] ; Almeida, Emerson Rodrigo [1] ; Bortolozo, Cassiano Antonio [1] ; Monteiro dos Santos, Fernando Acacio [2]
Total Authors: 4
[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer IAG, Dept Geofis, BR-05508090 Sao Paulo - Brazil
[2] Lisbon Univ CGUL, Ctr Geophys, Lisbon - Portugal
Total Affiliations: 2
Document type: Journal article
Source: JOURNAL OF APPLIED GEOPHYSICS; v. 82, p. 75-83, JUL 2012.
Web of Science Citations: 4

This article presents TDEM results from an area with recent induced shallow seismicity. The purpose was to do a geoelectrical mapping of sedimentary and fractured basaltic aquifers for better understanding of the hydrogeologic setting. The study area is in the Parana basin where flood basalts are overlain by sedimentary units near the city of Bebedouro, northern Sao Paulo State, Brazil. 86 TDEM soundings were acquired in an area of 90 km(2) in the Andes and Botafogo study areas. The soundings were chosen next to wells for calibration, and also along profiles crossing the seismically active areas. 1-D interpretation results showed the general geoelectrical stratigraphy of this part of the Parana basin. The upper geoelectrical layer is the shallow sedimentary aquifer (Adamantina formation) with less than 80 m thickness. The second geoelectrical layer contains the upper basalts of the Serra Geral formation at about 60-80 m depths. A saturated fractured basalt zone between 100 and 300 m depths was identifiable on various TDEM soundings. This depth range corresponds to the range of hypocentral depths for more than 3000 micro-earthquakes in this area. The lower basalt layer was estimated to lie between 400 and 650 m depth. The deepest geoelectrical layer detected by various TDEM soundings corresponds to the Botucatu sandstone (Guarani aquifer). Results suggest that the high-discharge wells are located in the fractured zone in the middle basalt of the Serra Geral formation. There is a good correlation between seismically active areas, high discharge wells (>190 m(3)/h), and fracture zones in the middle basalt. The results reinforce the hypothesis that the shallow seismic activity in the Bebedouro region is being triggered by high rates of groundwater withdrawal. (C) 2012 Elsevier B.V. All rights reserved. (AU)

FAPESP's process: 12/02709-4 - TDEM survey in an area of seismicity induced by water wells in Paraná sedimentary basin, Northern São Paulo State, Brazil
Grantee:Jorge Luís Porsani
Support type: Regular Research Grants - Publications - Scientific article
FAPESP's process: 09/08466-3 - Geoelectric characterization of fractured aquifers in basalt in the region of Bebedouro, SP, by using joint inversion of SEVs and TDEM soundings
Grantee:Jorge Luís Porsani
Support type: Regular Research Grants
FAPESP's process: 07/04325-0 - Water-well induced earthquakes in Bebedouro, SP: evolution of the seismicity and structural causes
Grantee:Marcelo Sousa de Assumpção
Support type: Regular Research Grants