A microseismic approach to locate survivors in the wreckage of a disaster

Detection of microseismic events generated by survivors trapped under rubble is a method already used by Search and Rescue (S&R) teams worldwide. Present seismic S&R equipment work exclusively on energy analysis while ignore information carried by propagation delays. Thanks to the development of a new seismic S&R digital system, I explore the potential of traveltime analysis compared to energy analysis for 2D and 3D localization. Results obtained in three debris fields used for training S&R teams demonstrate that traveltimes are not less reliable than energy. A joint analysis of both the signal parameters can be an appropriate strategy to improve the 2D localization reliability. Besides, traveltimes can potentially extend the localization to the third dimension by returning an approximate estimate of the survivor depth. Main obstacles to achieve this goal are the heterogeneity of the debris pile, the need of a real-time response, the limited extension of the sensor array along the vertical direction. Despite of these difficulties, results obtained in the fields with an algorithm based on data focusing by means of crosscorrelation and semblance operators generally show accuracy in the limit of the seismic resolution. The localization algorithm is flexible and can be customized to face the peculiar constraints posed by this application. A newly defined searching strategy involving 2D and 3D localization procedures in sequence, allows to reduce time of operations by a factor of 3 with respect to current seismic S&R searching methodologies.