LocSAT

LOCSAT locator for SeisComP.

Description

The LocSAT locator interface implements a wrapper for the LocSAT locator written by Walter Nagy (according to the README file shipped with the LocSAT distribution).

Travel time tables

SeisComP ships with two predefined travel time tables: tab and iasp91. LocSAT travel time tables are located under share/locsat/tables/.

The default profile is iasp91.

Station corrections

LocSAT does not support station corrections natively. At least checking the code:

sta_cor[i]  = 0.0;    /* FIX !!!!!!*/

However the SeisComP wrapper adds this feature. It allows to define a .stacor file which defines corrections of observation times in seconds. A correction is subtracted (not added) from the observation time to be compatible with the NonLinLoc station correction definitions (http://alomax.free.fr/nlloc/soft3.03/control.html#_NLLoc_locdelay_).

Each LocSAT profile (travel time table) can have an associated station correction file. To use station corrections for the iasp91 tables, the file share/locsat/tables/iasp91.stacor needs to be created.

A station correction table looks like this:

# LOCDELAY code phase numReadings delay
LOCDELAY GE.MORC P 1 -0.1

The fourth column (numReadings) is ignored and just provided for compatibility reasons with NonLinLoc.

Format

  • code (string) station code (after all alias evaluations)

  • phase (string) phase type (any of the available travel time tables)

  • numReadings (integer) number of residuals used to calculate mean residual/delay (not used by NLLoc, included for compatibility with the format of a summary, phase statistics file)

  • delay (float) delay in seconds, subtracted from observed time

Configuration

LOCSAT.profiles

Type: list:string

Defines a list of available LOCSAT tab directories. Default is iasp91,tab.

LOCSAT.enableConfidenceEllipsoid

Type: boolean

Compute the confidence ellipsoid. Default is false.

LOCSAT.depthInit

Type: double

Unit: km

The initial depth estimate for LocSAT. Default is 20.0.

LOCSAT.defaultTimeError

Type: double

Unit: s

The default pick time uncertainty assigned to LocSATs arrival deltim attribute if pick uncertainties are not going to be used or if they are absent. A time uncertainty of 0 s may result in errors of the SVD decomposition in LocSAT. Default is 1.0.

LOCSAT.usePickUncertainties

Type: boolean

Whether to use pick time untertainties for arrival deltim rather than a fixed time error. If true then the uncertainties are retrieved from each individual pick object. If they are not defined then the default pick time uncertainty will be used as fallback. Default is false.