Evaluation of the correlation between overexploitation of karst aquifers and seismicity the Alto Verde Grande Region

Abstract

In river basins with limited water availability and water deficits, abstracting groundwater through deep wells becomes essential to meet the demand of the basin's various users. The Alto Verde Grande basin, located in Minas Gerais, Brazil, is predominantly made up of rocks of the Bambuí Group, where karst aquifers occur. According to a survey in the Groundwater Information System of the Mineral Resources Research Company (SIAGAS-CPRM), there are more than 1,200 groundwater pumping wells in the area (3,101.23 km²). Groundwater abstraction of this density from wells can lower the water table, resulting in temporal and geographical variations in pore pressures in aquifers that can induce earthquakes a few kilometers underground. In parallel, it was discovered that in a 200 km radius of the Montes Claros region, 142 earthquakes happened between 1931 and 2019, 105 of them within a 30 km radius of Montes Claros. Evaluating the locations of seismic events, climatological graphs, and geological maps, the analysis indicates a water deficit and seismic activity in the region. To foster the UN Groundwater Agenda for 2022 - Making the Invisible Visible - this study sought to understand the relationship, if any, between seismic activity in the Alto Verde Grande basin and groundwater abstraction by deep wells.