Data Services Products: Infrasound-AELUMA Automated Event Location Using a Mesh of Arrays

Summary

The AELUMA (Automated Event Location Using a Mesh of Arrays, de Groot-Hedlin and Hedlin, 2015) detection and location algorithm is used to expand IRIS DMC’s infrasound event repository. The USArray TA station’s infrasound data for 2011-2015 are processed and over 2500 automated infrasound source locations were obtained. These events and those of the TA Infrasound Reference Event Database (TAIRED) were merged to form the IRIS DMC’s infrasound event database.

Description

AELUMA (Automated Event Location Using a Mesh of Arrays) is a new detection and location method, developed by de Groot-Hedlin and Hedlin (2015). This algorithm allows division of a sufficiently dense network such as the Transportable Array (TA) component of the USArray/EarthScope project (map) into a mesh of three-element arrays (triads). The time and azimuth of the detected signals from the cluster of these triads is then used to locate the source of the detected signals. The TA infrasound data has been processed by this algorithm and over 2500 resulting events were added to the IRIS DMC’s Infrasound Event Database from 2011-2015 when the densest portion of the infrasound network was active.

Infrasound Event Database

AELUMA events and the existing TA Infrasound Reference Event Database (TAIRED) events are merged to form IRIS DMC’s infrasound event database. This database is available for download as a text file via our Searchable Product Depository (SPUD). SPUD’s event selection filters allows limiting downloaded events to specific location, time, number of contributing stations and/or author.

The database columns are:

Event ID | Origin ID | Origin Time | Title | Event Type | Event Status | ParamId | Latitude | Longitude | NumStations | Mean Celerity | Celerity Std | Triad | Badness | Mean Xcor | Author | Reference

where

  • Event ID — Event identifier
  • Origin ID — A unique origin (solution) identifier

Note: Associated origins (different solutions for the same event) share the same event ID (e.g. associated AELUMA and TAIRED events will have different Origin_IDs but the same Event_ID)

  • Origin Time — Origin’s Date and Time
  • Title — Event description (AELUMA: this is a reference to the event ID. TAIRED: this is a short description for the event)
  • Event Type — Event or source type (Bolide, Bulletin Event, Detection, Earthquake, Explosion, Infrasound, Meteorological, Mining, N-Wave, Rocket Launch, Rocket Re-entry, Volcano, Unknown). Automated AELUMA events all have Detection as the event type.
  • Event Status — type of analysis that has gone into building the event:
    • Automatic event was built by an automated process
    • Reviewed, event is based on the review of infrasound waveforms (not necessarily TA waveforms)
    • Observed, event is documented but no infrasound review has been performed
    • Not Verified, the event is not verified
  • ParamId — Parameter identifier for the set of parameters used for AELUMA detection and location algorithms. Parameter list is available for download from the corresponding AELUMA event detail page (see below).
  • Latitude — Source latitude
  • Longitude — Source longitude
  • NumStationsAELUMA: total number of stations included in detecting triads. TAIRED: number of stations displayed on the record section
  • Mean Celerity — Mean celerity of signals (m/sec)
  • Celerity StdAELUMA: celerity standard deviation (m/sec)
  • TriadsAELUMA: total number of triads in cluster
  • BadnessAELUMA: solution quality (0: best, 1: source on the edge of search grid, 10: source on the time grid boundary)
  • Mean XcorAELUMA: mean record correlation
  • Author — Event author
  • Reference – Author’s reference

Event Detail Page

For each event SPUD provides an event detail page that includes:

  • corresponding event parameters
  • event and station location map, event record section (as shown by the above figures)
  • if the solution is an associated solution, a link to the associated solution is provided
  • at the bottom of the page you will find the following links:


    • a link to download figures
    • a link to download station list in the following format:
onrecord | network | station | latitude | longitude | distance | elevation | azimuth | backazimuth

  • onrecord — station trace plotted on the record section (0: station trace does not contribute to the record section, 1: station trace is plotted on the record section but it is not an AELUMA detecting station, 2 station is an AELUMA detecting station and is trace is plotted on the record section)
  • network — network code
  • station — station code
  • latitude — station latitude
  • longitude — station longitude
  • distance — distance from source in degrees
  • elevation — station elevation
  • azimuth — station to source azimuth
  • backazimuth — station to source back azimuth

a link to download a list of parameters used by AELUMA for detection and location in the following format:

paramid | application | name | value

  • paramid — parameter file ID (for DMC internal use)
  • application — where the parameter was used (detection: for detection, event: for event location)
  • name — parameter name in AELUMA code
  • value — parameter value

Script Bundle

AELUMA MATLAB code bundle (current version R.2017.010) is available from IRIS DMC under the included Source Code License Agreement. To obtain a copy of this bundle, send your requests to product@iris.washington.edu.

Citations and DOIs

To cite the IRIS DMC Data Products effort:

  • Hutko, A. R., M. Bahavar, C. Trabant, R. T. Weekly, M. Van Fossen, T. Ahern (2017), Data Products at the IRIS‐DMC: Growth and Usage, Seismological Research Letters, 88, no. 3, doi:10.1785/0220160190.

To cite the source of AELUMA (Automated Event Location Using a Mesh of Arrays) events :

  • Catherine D. de Groot-Hedlin and Michael A.H. Hedlin, 2015, A method for detecting and locating geophysical events using groups of arrays, Geophys. J. Int. 2015 203: 960-971,doi:10.1093/gji/ggv345.

To cite the IRIS DMC Infrasound TA Infrasound Data Products or reference use of its repositories:

  • IRIS DMC (2012), Data Services Products: Infrasound TA Infrasound Data Products, doi:10.17611/DP/IS.1.

Credits

  • Catherine de Groot-Hedlin
    University of California, San Diego
  • Michael Hedlin
    University of California, San Diego
  • Manochehr Bahavar
    IRIS DMC

Timeline

2016-06-15
Released

Contributors

Catherine de Groot-Hedlin
University of California, San Diego

Michael Hedlin
University of California, San Diego

Categories

Tags

infrasound