(c) 2006-2013 Claudio Satriano [email protected], Anthony Lomax [email protected]

RTLoc is an evolutionary, real-time earthquake location technique based on an equal differential time (EDT) formulation and a probabilistic approach for describing the hypocenter estimation.

The algorithm, at each timestep, relies on the information from triggered arrivals and not-yet-triggered stations. With just one recorded arrival, the hypocentral location is constrained by the Voronoi cell around the first triggering station constructed using the travel times to the not-yet-triggered stations.

With two or more triggered arrivals, the location is constrained by the intersection of the volume defined by the Voronoi cells for the remaining, not-yet-triggered stations and the EDT surfaces between all pairs of triggered arrivals.

As time passes and more triggers become available, the evolutionary location converges to a standard EDT location.

RTLoc is written in pure C, without any external library dependence. It can be compiled by a C or C++ compiler.

To compile, edit the Makefile by selecting the installation prefix and the compiler executable, then run:

make

and, optionally,

make install

in case you want to copy the executable to your prefix path.

Grid2Time program from Anthony Lomax (part of the NonLinLoc suite) is required to generate traveltime grids.

Plotting routines are written in Python and require matplotlib.

See doc/usage.md for usage instructions.

A complete text case is available in the testrun/ directory. See testrun/README.md for instructions on how to run the test.

This is a research implementation of the code, with no actual real-time capabilities.

Feel free to pick the relevant parts of this (GPL licensed) code and build your own real-time module!

A real-time implementation of RTLoc --which processes continuous seedlink streams-- is available within PRESTo, a free and open source software platform for Earthquake Early Warning developed at the RISSC-Lab, Naples, Italy.

Satriano, C., Lomax, A., Zollo, A. 2008. Real-Time Evolutionary Earthquake Location for Seismic Early Warning. Bull. Seismol. Soc. Am., 98(3), 1482–1494. doi: 10.1785/0120060159.

THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.