Localisation of Earthquake Foci for EEWs

This small volume aims to suggest and demonstrate a collection of methods whereby very rapid scans for the Hypocenter foci can take place in real-time or near real-time. These scans have been, to some extent, given in other places and are to be executed, in part, by point-to-point (P2P) ray-tracers or Tabular Scans. These ray tracers act from a set of depth-points from which the scan constructs rays to each of the active seismographs which are in possession of a P-wave or S-wave onset timing. The P2P tracers employ any of a set of 1-D (radial) Earth velocity models and use a set of possible "indicator functions" whose response shall determine an estimate of the Hypocenter Depth.