Showing papers on "Sinkhole published in 1987"

Potential for pollution of the Upper Floridan aquifer from five sinkholes and an internally drained basin in west-central Florida

Abstract: Sinkholes are natural and common geologic features in west-central Florida, which is underlain by water-soluble limestone deposits. Dissolution of these deposits is the fundamental cause of sinkhole development. Sinkholes and other karst features are more pronounced in the northern part of the study area, but sinkhole activity has occurred throughout the area. Fifty-eight sinkholes with known or suspected connection to the Upper Floridan aquifer are located in the study area. An internally drained basin near the city of Brandon and five sinkholes in Hillsborough, Pasco, and Hernando Counties were selected for detailed investigation. At all sites, chemical or biological constituents were detected that indicate pollutants had entered the aquifer. A generalized classification, based on the potential to pollute, was applied to the selected sites. Four of the sites have high potential and two have moderate potential to pollute the Upper Floridan aquifer. All of the sites investigated are capable of recharging large volumes of water to the Upper Floridan aquifer in short periods of time. Continued monitoring of the quality of water entering the sinkholes and of wells downgradient to the sinks is needed to assess the future impacts on the aquifer.

Use of Acoustic Emission and Seismic Tomography Techniques to Study Sinkhole Development

Abstract: The uncontrolled development of cavities near the earth's surface, due to natural or man-made causes, pose a major engineering hazard. Regardless of the cause, these cavities can result in localized instabilities such as the collapse of highway or airport runway pavements, foundation subsidence or collapse, and dam leakage. The purpose of the study outlined in this paper was to investigate the feasibility of using acoustic emission and seismic tomography techniques to study the development of one type of near-surface cavity known as a "sinkhole." In recent years, sinkholes have developed under large sections of the airport runway and taxiway complex at the Capital City Airport, near Harrisburg, Pennsylvania, U.S.A.. During the study, instrumentation for carrying out low-frequency acoustic emission and near-surface S-wave seismic tomography studies were installed at selected areas. This paper will present preliminary results of this ongoing study.

Regional inventory of karst activity in the Valley and Ridge Province, eastern Tennessee: Phase 1

Abstract: A data collection form was developed for use in compiling information in the inventory. Information sources included files on subsidence, state and county highway departments, county agents and executives, soil conservation service representative, etc. Data obtained included location, date of occurrence, number of subsidence features at the reported site, size, topographic setting, geologic setting, and probable causative factors. The regional inventory obtained information on over 300 historic subsidence events at more than 200 sites in East Tennessee. Areas having the greatest areal density of active subsidence include Hamblen, Jefferson, and Loudon Counties. Reported subsidence events occurred between 1945 and 1986. The Knox Group dolomites account for about two-thirds of all reported sinkholes in the inventory. Most of the karst activity occurs in valleys or flat areas. In cases where causative factors could be established, the combination of surface water drainage alteration or impoundment combined with soil disturbance associated with construction activity were most often precursors to subsidence. 54 refs., 10 figs., 4 tabs.