A microseismic approach to locate survivors trapped under rubble

摘要

The detection of microseismic noise generated by survivors trapped by debris is a method already used by Search and Rescue (S&R) teams. Present seismic S&R equipment works exclusively on energy analysis whilst ignoring information associated with propagation delays. We explore the potential of using traveltime analysis compared to energy analysis for both 2D and 3D location. Results obtained from three different debris field scenarios used for training S&R teams demonstrate that using travel-time information is more reliable than using energy information alone. A joint analysis of both signal parameters is suggested as an appropriate strategy to improve the reliability of locating survivors. Traveltimes can also potentially extend the location into the third dimension by returning an approximate estimate of the survivor depth below ground level. The main obstacles to achieving this goal are the inhomogeneity of the debris pile, the need for a real-time response and the limited spatial extension of the sensor array. Despite these difficulties, results obtained in the field, with an algorithm based on energy focusing by means of cross-correlation and semblance operators, show an accuracy within the limit of the seismic resolution. A new searching strategy is defined and the procedure reduces the investigation time taken by current seismic S&R systems by a factor of three.