Optimal, Real-time Earthquake Location for Early Warning

An effective early warning system must be capable of estimating the location and size of a potentially destructive earthquake within a few seconds after the event is first detected. In this work we present an evolutionary, real-time location technique, based on the equal differential time (EDT) formulation and on a probabilistic approach for hypocenter estimation. The algorithm, at each time step, relies on the information coming from triggered arrivals and not yet triggered station. With just one recorded arrival, hypocentral position can be constrained by the Voronoi cell associated to the first triggering station. As time passes and more triggers become available, the evolutionary location converges to a standard EDT location. We performed synthetic location tests using the actual geometry of the ISNet (Irpinia Seismic Network, Southern Italy) in order to evaluate the accuracy of the algorithm and its robustness in the presence of outliers.