.. _mt-introduction:

Introduction
============

|appname| is a package for automatic or interactive inversion for seismic
:term:`moment tensors <moment tensor>` in real-time or during post-processing.

Our moment tensor inversion technique uses a combination of several seismic wave
types, time windows and frequency bands carefully chosen based on event magnitude
and station distance. Wave types include body waves, surface waves, mantle waves
as well as the so-called 'W-Phase' :cite:t:`kanamori-2008`. The inversion is
performed in the time domain only based on the algorithm set out by
:cite:t:`minson-2008`. An iterative centroid search can be performed
independently either in 3D or and in depth.
We apply moment tensor decomposition based on :cite:t:`silver-1982`
and :cite:t:`knopoff-1970`. The full methodology including moment-tensor
decomposition is described in section :ref:`scautomt-event-processing`.

Moment tensors can be computed in an automatic fashion within a few seconds of
waveform data becoming available. Prior to publication, solutions can be reviewed
by an analyst using the graphical user interfaces. Therefore, the |appname| package
consists of two modules:

* The :ref:`automatic module <scautomt>` |appbin| which typically runs as daemon tool
  computing 3D-centroid moment-tensor solutions. Automatic post-processing can be
  triggered by command-line options.
* The :ref:`interactive module <scmtv>` |appvbin| used by operators to revise
  and test solutions or to define the best configuration parameters for |appbin|.


.. raw:: html

   <div class="four column layout">

.. figure:: media/mainview_intro_w.png
   :alt: arrival times

   In the main view, events are selected and visualized.

.. figure:: media/editor-intro_w.png
   :alt: forecast zones

   The waveform editor provides full control over moment tensor inversion.

.. figure:: media/depthsearch_intro_w.png
   :alt: mariograms

   Interactive and automatic Centroid search constrain earthquake depth.

.. figure:: media/statistics_intro_w.png
   :alt: SSHmax

   Single-station inversions and Monte-Carlo tests confirm final solutions.

.. raw:: html

   </div>


Applications
------------

* Local, national and regional networks for earthquake monitoring
* Tsunami early warning
* Fast determination of moment magnitude and focal mechanism


Features
--------

* Rapid moment tensor inversion in the time domain
* Real-time module fully integrated into |scname|
* Real-time restitution for maximum speed
* Fits body waves, surface waves, mantle waves and W-phases
* Configurable profiles for magnitude ranges
* :ref:`Fully automatic analysis <scautomt>`
* :ref:`Interactive analysis <scmtv>`


|appname| worldwide
-------------------

Nowadays |appname| is operational worldwide in many institutions where fast and reliable
automatic and user-friendly tsunami early warning is key. Some reference installations are:

* Indonesia
* `DGMET <http://www.met.gov.om/>`_, Oman
* `Geological Nuclear Science, GNS <https://www.geonet.org.nz/>`_, New Zealand
* `Central American Tsunami Advisory Center (CATAC) <http://catac.ineter.gob.ni/>`_ established at Instituto
  Nicaragüense de Estudios Territoriales (Nicaraguan Geosciences Institute, INETER) in Managua, Nicaragua.
* Singapore


Science Publications
====================

|appvbin| and |appbin| have been operational in real time in many data centers world wide
where fast and reliable moment tensor determination is key.
The results have been used, demonstrated, promoted and discussed with scientists
and the |scname| community in scientific publications and at international science conferences, e.g.:

#. W. Hanka, J. Saul, B. Weber, J. Becker, P. Harjadi, Fauzi, and GITEWS Seismology Group,
   Real-time earthquake monitoring for tsunami warning in the Indian Ocean and beyond,
   2010, Nat. Haz. Earth Sys. Sci., 10 (2611-2622),
   doi: `10.5194/nhess-10-2611-2010 <https://www.nat-hazards-earth-syst-sci.net/10/2611/2010/nhess-10-2611-2010.pdf>`_
#. J. Saul, J. Becker, W. Hanka, Global moment tensor computation at GFZ Potsdam, 2011.
   AGU Fall Meeting, Sn Francisco, USA, abstract ID. `S51A-2202 <https://ui.adsabs.harvard.edu/abs/2011AGUFM.S51A2202S>`_
#. D. Roessler, S. Al-Harthy, B. Weber, B. Alrumhi, and the team of gempa, Monitoring
   of earthquakes and tsunamis at the National Tsunami Warning Center of DGMET, Oman, 2018,
   10th Gulf Seismic Forum, Muscat, Oman


.. _mt-online:

Online Resources
================

You may watch videos on our YouTube channel:

* MT tools on |gempa| YouTube channel : https://www.youtube.com/watch?v=B9JlMF_3JZA
* gempa YouTube channel: https://www.youtube.com/channel/UCDzbPWlqWw0TyDzReTsU8SQ