Analysis of the risk of karst collapse in Lapão, Bahia, Brazil

Abstract

On October 2008, the large extent of dissolution of limestone in the Irecê Basin resulted in the occurrence of minor ground shakes and the enhancement of fractures along the surface of the ground and on the walls of buildings in the urban and periurban area of the city of Lapão. After preliminary geological and geotechnical studies to analyse the danger of collapse of underground caves, we have carried out gravity and electro-resistivity profiles in order to map the concealed caves and to help the determination of the level of groundwater within them. The interpretation of the results provided useful information both for the immediate safety of the population and for subsequent hydrological and geotechnical work. We have defined five risk areas based on the variations of the Bouguer and of the electrical resistivity data, by correlating the distribution of gravity lows with the presence of caves and the less resistive zones with the presence of brine water underground. (a) ( b) Fig. 1. (a) Cracks along a downtown street of the city of Lapão. (b) Fractures in a plantation of onions.

The Analyses of Land Use and Prevention in High-Density Main Urban Areas under the Constraint of Karst Ground Subsidence: Study of Wuhan City, China

“…Some scholars mainly study the susceptibility to KGS in the construction sites of major linear projects. A few scholars utilize historical, geophysical, and geological methods to analyze karst environments to prevent urban development in hazardous areas [19][20][21]. However, there is still a lack of analysis from both the perspective of geological, environmental conditions and the intensity of large-scale engineering construction activities regarding the restrictive effect of karst ground collapse on land use in central urban areas (small-scale areas with high-intensity human activities).…”

The Potential Use of Geophysical Methods to Identify Cavities, Sinkholes and Pathways for Water Infiltration

“…The caves are broadly divided into two main groups as carbonated karst and non-carbonated karst of which carbonated karst is relatively more studied, however, the study of karst in Brazil is still in the infancy stage and requires further detailed analysis [34]. The prominent karst studies in Brazil are presented in the literature [35][36][37].…”

Detection of Cover Collapse Doline and Other Epikarst Features by Multiple Geophysical Techniques, Case Study of Tarimba Cave, Brazil

“…In Brazil, the following research works have been applied for the analysis of several caves across the country: [26][27][28][29][30]. However, no previous study has applied geophysical investigation to characterize the caves in the preserved area of the Mambaí, Goiás (River Vermelho) where borehole drilling is prohibited.…”