Welcome to the LEGACY NonLinLoc home page…

See https://github.com/alomax/NonLinLoc page for a description of New Releases, Updates and Bugs.

See the FAQ page for answers to Frequently Asked Questions.

New: NLLGrid - Python class for reading and writing NonLinLoc grid files. By Claudio Satriano, Natalia Poiata: NLLGrid

Most of the NonLinLoc software is distributed under the GNU General Public License (GNU GPL). (or look at a local copy of the GNU General Public License).

Previous release: NonLinLoc Version 7.00

The NonLinLoc (Non-Linear Location) package is a set of programs for velocity model construction, travel-time calculation and probabilistic, non-linear, global-search earthquake location in 3D structures, and for visualisation of 3D volume data and location results. Many of the programs operate with a 3D Grid structure which defines a specific, gridded, rectangular volume (Non-GLOBAL mode) or spherical section (GLOBAL mode).

See the NLLoc program documentation for a description of the non-linear location inversion approach and algorithms.

See the book chapters Probabilistic earthquake location in 3D and layered models: Introduction of a Metropolis-Gibbs method and comparison with linear locations (Lomax, et al., 2000) and Earthquake Location, Direct, Global-Search Methods (Lomax, et al., 2009) for further information on NonLinLoc and for an examination of synthetic 3D and 1D locations.

See the report Comparison of NonLinLoc and linear earthquake locations in a 3D model for an examination of real 3D locations.

NonLinLoc supports regional/teleseismic location in a spherical, longitude/latitude/depth coordinate system. This is referred to as the "GLOBAL" mode in this documentation. The original rectangular-Cartesian location mode remains fully supported, and is referred to as the "Non-GLOBAL" mode where relevant.

NonLinLoc includes the Equal-Differential Time (EDT) likelihood function in addition to the classic L2/RMS function (see EDT likelihood function).

NOTE: Currently, the NonLinLoc package only includes software support for generating 1D, spherically-layered travel time grids for GLOBAL mode location.  External software can be used to generate 3D travel time grids in spherical coordinates for GLOBAL mode.  (A Fast Marching Method, finite-differences package for calculating travel times on 3D spherical-ellipsoidal grids is currently under development, contact Anthony Lomax for more information anthony@alomax.net)

NLLoc

Non-GLOBAL
GLOBAL

Non-Linear Location - Determines the location for one or more events within a 3D Grid using a systematic grid-search, a stochastic, Metropolis-Gibbs search, or a hybrid "Oct-Tree" method. (outputs misfit or probability density function (PDF) on a 3D Grid, PDF samples or "scatter cloud", description of best hypocenter, and other results).

Vel2Grid

Non-GLOBAL

Velocity model to 3D Model Grid - Given a velocity model description, creates a model grid. (outputs a 3D Grid)

Vel2Grid3D

Non-GLOBAL

Existing 3D velocity model to 3D Model Grid – Converts an existing 3D velocity models defined by interpolation between control point nodes and created by velocity inversion programs such as SimulPS, Simul2000 and FDTomo to a 3D model grid. (outputs a 3D Grid)

Grid2Time

Non-GLOBAL

3D Model Grid to Travel Time Grid - Given a 3D Model Grid, calculates travel times from a point within a 3D Grid to all other points within the grid. Optionally calculates ray take-off angles within the 3D Grid. (outputs a set of 3D Grids)

Time2EQ

Non-GLOBAL
GLOBAL

Travel Time Grid to Synthetic Observations - Given a hypocenter location and a set of travel time grids, calculated predicted travel times. (outputs a Phase file in NonLinLoc format)

LocSum

Non-GLOBAL

Location Summation - Utility that combines NLLoc location results and PDF "scatter-cloud" samples from a number of events. (outputs a single set of summary location files)

Grid2GMT

Non-GLOBAL

Grid to GMT commands - Utility that creates a command script for plotting plotting sections and plan views of 3D Grid files, and misfit, PDF and location "scatter-cloud" results using the GMT plotting package. NOTE: Currently requires GMT4, GMT5 not yet supported.

Utilities

Non-GLOBAL

Miscellaneous utility programs - Utilities for conversion between HYPOELLIPSE summary or FPFIT summary formats and NonLinLoc Hypocenter-Phase location format.

In addition, the following analysis and visualisation software supports NonLinLoc event location output formats:

SeismicityViewer

Non-GLOBAL
GLOBAL

Java applet for viewing seismicity in 3D - Interactive, animated, local or Internet-based viewing in 3D of hypocenters, PDF "scatter-clouds", error-ellipses, residuals, geographic data and other information.

A typical Non-GLOBAL mode location run involves:

1. obtaining seismic phase time picks in a supported format (see Phase File Formats)

2. determining a 3D search region and velocity model for this region

3. using Vel2Grid or other software to produce a velocity or slowness model 3D Grid File for the search region for each phase type, (i.e. P or S).

4. using Grid2Time to produce travel-time and ray take-off angle 3D Grid Files for each phase type at each station

5. using NLLoc to locate each event defined by the phase picks using an Oct-tree, nested grid-search or Metropolis-Gibbs search over a 3D volume

6. using the utilities LocSum and Grid2GMT or SeismicityViewer to process and plot the location results

A typical GLOBAL mode location run involves:

1. obtaining seismic phase time picks in a supported format (see Phase File Formats)

2. determining a 3D search region and velocity model for this region

3. using

   1. the Java package TauPToolkit with the NonLinLoc Java class edu.sc.seis.TauP.TauP_Table_NLL to create 1D, spherically-layered travel-time 3D Grid Files for each phase type at individual or multiple stations (travel-time files with station code "DEFAULT"), or other software to produce 1D or 3D travel-time 3D Grid Files for each phase type at each station

4. using NLLoc to locate each event defined by the phase picks using an Oct-tree, nested grid-search or Metropolis-Gibbs search over a 3D volume

5. using SeismicityViewer to process and plot the location results

NonLinLoc

Version 7.0.0 (Sep 2017)
- Download the NonLinLoc Software and compile it on your machine: Source code and makefile, or
- Download the NonLinLoc Mac OS X 10 binary executables: Mac OS X binaries

NOTES:

1. Linux, Solaris: With gcc and Sun Solaris 2.6 on a Sun Workstation I have successfully compiled the NonLinLoc software using the command make distrib. With gcc and Linux (SuSE) on a Pentium or AMD PC I have successfully compiled the NonLinLoc software using the command gmake -R distrib. If you have successfully installed and run the NonLinLoc software on another system, I would appreciate hearing about the details of your hardware, operating system, compiler and compiler flags. Thanks. anthony@alomax.net

2. Mac OS X: NonLinLoc should now compile on Mac OS X as above for Linux, Solaris. Previously, Gilles Celli has kindly provided details of how to compile the NonLinLoc software on Mac OS X 10.5.5 (Leopard) on iMac with an INTEL processor. For more information or a copy of the NonLinLoc Max OS binaries, contact Gilles Celli: CGS (http://www.ecgs.lu) email:gilles.celli[AT]ecgs.lu

3. Grid2GMT: I have made changes to Grid2GMT to support GMT 3.3.6, though there seems to be bugs or other problems, i.e. the labelling of scale bars is incorrect. If you use an earlier version of GMT, you may need to change the line #define GMT_VER_3_3_4 1 in Grid2GMT to #define GMT_VER_3_3_4 0.

SeismicityViewer

Download the SeismicityViewer java code and class files: SeismicityViewer

Download the NonLinLoc Sample Locations files: Sample location files

Non-GLOBAL mode: Instructions to run the Sample Location tutorial for local events, to create a velocity grid, calculate travel times and locate an event, and visualise the results results.

GLOBAL mode: Instructions to run the Sample Location tutorial for regional/teleseismic events, to create a travel-time grid, locate an event, and visualise the results results.

Please mail questions, comments or suggestions to anthony@alomax.net

The utility, quality and evolution of the NonLinLoc software package depends entirely on feedback from its users. Many thanks to many people for feedback, and to the following people for particularly extensive support, contributions, bug reports, comments and suggestions for the NonLinLoc software:

Philippe Volant, Catherine Berge, Jean Virieux, Alberto Michelini, Stephan Husen, Giuseppe Aliberti, Alexandre Nercession, Rick Aster, Mariella Simini, Jerry Sweeney, Laura Sattolo, Paolo Di Bartolomeo, Carsten Riedel, David Monterroso, Yvonne Font, Charlotte Rowe, Antonio Villaseñor, Sylvain Bouley, Vasile Marza, Lucas Barros, Sudipta Sarkar, Dimitris Dimitropoulus, Frederik Tilmann, Enrique Mercerat, Ivan Lehocki, Gilles Mazet-Roux, Ana Luísa Pinho, Paul, Thorsten Becker, Andy Heath, Andreas Rietbrock, Gilles Celli, Claudio Satriano, Edith Korger,

... AND MANY OTHERS!