.. _scanloc-ttt:

Dense Travel-Time Tables
========================

The default travel time tables of SeisComP for :cite:t:`locsat` provide the
times in intervals of 1 degree epicentral distance. Thus, the curvature of the
travel-time curve at closer distance is not well imaged potentially resulting in
wrong locations or missing event solutions. Therefore, the LOCSAT tables,
*iasp91_scanloc*, based on the IASP91 model with higher spacial sampling are
added to the scanloc package. The table files are located in
:file:`$SEISCOMP_ROOT/share/locsat/tables`. They may be used along with scanloc
and any other module which uses LOCSAT travel-time tables such as :cite:t:`scolv`,
:cite:t:`scautoloc`, :cite:t:`screloc` or even the locator :cite:t:`stdloc`.

.. note::

   gempa may provide additional travel-time tables as a service based on custom
   velocity models. `Contact <https://www.gempa.de/contact/>`_ us for any
   related request.

.. _fig-ttt-scanloc:

.. figure:: ../apps/media/ttt_scanloc_P_5km.png
   :align: center
   :width: 18cm

   Differences between P-wave travel times in the standard iasp91 tables for LOCSAT
   and the iasp91_scanloc tables provided with scanloc for an event at 5 km depth.


Application in scanloc
----------------------

Configure the scanloc parameters :confval:`association.table` and
:confval:`locator.profile` with *iasp91_scanloc* for using these LOCSAT tables
in scanloc along with LOCSAT:

.. code-block:: params

   # Type of travel-time tables for phase association. May be different from locator.
   # Use e.g. libtau or LOCSAT.
   association.tableType = LOCSAT

   # Name of travel-time table used for phase association. May be different from locator
   # profile.
   association.table = iasp91_scanloc

   # The locator type to use
   locator.type = LOCSAT

   # The locator profile to use
   locator.profile = iasp91_scanloc

Alternatively, you may use the tables along with :cite:t:`stdloc`.


Application in other modules
----------------------------

In order to visualize the travel times or for using the tables in applications
like :cite:t:`scolv` add the tables to your global module configuration:

.. code-block:: params

   ttt.LOCSAT.tables = iasp91_scanloc
   LOCSAT.profiles = iasp91_scanloc

More specific parameters may exist along with your application.