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

• Grant number: 12/02709-4
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Duration: April 01, 2012 - September 30, 2012
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Jorge Luís Porsani
• Grantee: Jorge Luís Porsani
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

This article presents TDEM results from an area with recent induced shallow seismicity. The14 purpose was to do a geoelectrical mapping of sedimentary and fractured basaltic aquifers for15 better understanding of the hydrogeologic setting. The study area is in the Paraná basin where16 flood basalts are overlain by sedimentary units near the city of Bebedouro, northern São PauloState, Brazil. 86 TDEM soundings were acquired in an area of 90 km2 17 in the Andes and18 Botafogo study areas. The soundings were chosen next to wells for calibration, and also along19 profiles crossing the seismically active areas. 1-D interpretation results showed the general20 geoelectrical stratigraphy of this part of the Paraná basin. The upper geoelectrical layer is the21 shallow sedimentary aquifer (Adamantina formation) with less than 80 m thickness. The22 second geoelectrical layer contains the upper basalts of the Serra Geral formation at about 60-23 80 m depths. A saturated fractured basalt zone between 100 and 300 m depths was*Marked ManuscriptClick here to view linked References2identifiable on various TDEM soundings. This depth range 24 corresponds to the range of25 hypocentral depths for more than 3000 micro-earthquakes in this area. The lower basalt layer26 was estimated to lie between 400 and 650 m depth. The deepest geoelectrical layer detected27 by various TDEM soundings corresponds to the Botucatu sandstone (Guarani aquifer).28 Results suggest that the high-discharge wells are located in the fractured zone in the middle29 basalt of the Serra Geral formation. There is a good correlation between seismically activeareas, high discharge wells (> 190 m330 /h), and fracture zones in the middle basalt. The results31 reinforce the hypothesis that the shallow seismic activity in the Bebedouro region is being32 triggered by high rates of groundwater withdrawal. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

PORSANI, JORGE LUIS; ALMEIDA, EMERSON RODRIGO; BORTOLOZO, CASSIANO ANTONIO; MONTEIRO DOS SANTOS, FERNANDO ACACIO. TDEM survey in an area of seismicity induced by water wells in Parana sedimentary basin, Northern Sao Paulo State, Brazil. JOURNAL OF APPLIED GEOPHYSICS, v. 82, p. 75-83, JUL 2012. (09/08466-3, 07/04325-0, 12/02709-4)