Undreground Void Mapping by High Resolution Seismic Reflection – Limits, Accuracy and Risk Assessment

H014 UNDREGROUND VOIDS MAPPING BY HIGH RESOLUTION SEISMIC REFLECTION: LIMITS ACCURACY AND ASSESSMENT OF COLLAPSE RISK SUMMARY The seismic techniques are applied successfully for seismic imaging of geological structures having great dimensions compared to wavelength (layers) but their application for detecting smaller targets as tunnels and cavities remains still limited. The paper presents the examples of the application of the high resolution seismic reflection (HRS) for the detection and localisation of underground voids. In order to express the detection as the function of cavity size the "anomaly coefficient" (AN) is proposed and used. It expresses "strength" of a cavity as