EPISODES Platform Documentation

Application User Guides > Source and Shaking Parameters Estimation

Phase Association user guide ​

TIP

This application implements PyOcto phase associator software which performs efficiently the association of arrival times that have been picked manually or automatically. As a result the application returns QuakeML file containing detected events together with their hypocenter locations and assigned arrival times. The application can be used in two ways: using a 1D velocity model (from a file) or using a 0D model (i.e. providing constant values of the velocity of seismic waves).
To obtain more general information about working with applications within the Platform, see Applications Quick Start Guide.

NOTE

CATEGORY Source and Shaking Parameters Estimation

KEYWORDS Source location, Seismic event detection, Hypocenter location

CITATION If you use the results or visualizations retrieved from this application in a publication, then you must cite the data source as follows:

Orlecka-Sikora, B., Lasocki, S., Kocot, J. et al. (2020) An open data infrastructure for the study of anthropogenic hazards linked to georesource exploitation., Sci Data 7, 89, doi: 10.1038/s41597-020-0429-3. Münchmeyer, J. (2024). PyOcto: A high-throughput seismic phase associator. Seismica, 3(1), doi: 10.26443/seismica.v3i1.1130

Input file specification ​

The application requires:

  • QuakeML file containing arrival times (from any time range)
  • XML file containing a seismic network inventory with stations coordinates

For best performance, also use:

  • velocity model file (in standard format on the platform - .mat)
Figure 1. Application input files specification.
Figure 1. Application input files specification.

Filling form values ​

The application form, in case of using velocity model file, consists of five required parameters - see Figure 2. The first three of them parameterize area in which events can be detected and located. Next two describe grid size for the 1D velocity model.

Figure 2. Application form with values filled in case of using velocity model file.
Figure 2. Application form with values filled in case of using velocity model file.

The application form, when using constant velocity model, also consists of five required parameters, two of which are different - see Figure 3.

In this case the first three parameters are the same. However, in this case there is no need to create a grid for the 1D velocity model. Instead, constant velocities for P and S wave have to be provided.

Figure 3. Application form with values filled in case of using constant velocities.
Figure 3. Application form with values filled in case of using constant velocities.

It is also possible to edit other, more advanced program parameters - see Figure 4, such as:

  • minimum number of picks (in total)
  • minimum number of P-wave picks
  • minimum number of S-wave picks
  • minimum number of pairs of P- and S-wave picks
  • time before: The overlap between consecutive time slices
  • tolerance Velocity model tolerance in s
  • association_cutoff_distance: Only use stations up to this distance for space-partitioning association
  • pick match tolerance: Maximum difference between the predicted travel time and the observed time for associating a pick to an origin in the refinement step.
  • P-wave hint: e. g. P, Pg etc.
  • S-wave hint: e. g. P, Pg etc.
Figure 4. Application form with advanced options.
Figure 4. Application form with advanced options.

Produced output ​

As a result program return QuakeML file containing list of detected events with assigned arrival times.

PyOcto documentation: https://pyocto.readthedocs.io/