f The experimental application of GPR to reveal the zones of soil cave-in and subsidence development in the city

We have used a ground-penetrating radar survey for detecting, and reveal zones of cave-in and subsidence development along a heath-pipes in Moscow. The problem is frequently observed along the heats-pipes and due to a long leaks. The survey had been in April with a «ZOND-12c» radar. In this period the frozen ground thickness is important. This GPR surveys were based on the high contrast in dielectric permittivity between hot-water saturated and frozen rocks . In this case, zones of cave-in and subsidence are characterized by a high water saturation. Near-surface survey was best imaged using a 300 and 150 MHz antennae. This papers shows how GPR can successfully reveal those zones in city’s conditions (high noise level).