Preliminary Ground Truth (GT) reference events (Proposed)
The IASPEI reference events list is a database of earthquakes and explosions, for which hypocentral information (lat, lon, depth) is known with high confidence (to 5 km or better (GT5)) with seismic signals recorded at regional and/or teleseismic distances. The database is maintained at the International Seismological Centre and currently contains 80445 events from 1959 to 2022.
The ISC has reviewed the existing GT List and added new GT events based on an updated criteria proposed by Gallacher et al. (2025). This work has added ~75,000 new GT events and removed 3,724 events which no longer meet the criteria to be a GT event. These 3,724 events and the 2,216 events previously found using a multi-event HDC-RCA methodology (Bondár et al., 2008) can still be found in the approved GT list. Pending approval at the Lisbon IASPEI Meeting in September 2025 this preliminary list will replace the existing GT List and the existing GT List will be retained here as a Legacy GT List. If you wish to give an opinion on this change you are welcome to attend the Working Group on Reference Events for Improved Locations meeting in September 2025 in Lisbon or you can email ryan@isc.ac.uk.
The global effort of collecting and validating GT events was initiated by the CoSOI/IASPEI Working Group on Reference Events for Improved Locations chaired by Bob Engdahl and Paul Richards.
Events may now be submitted to the ISC for validation. If you are interested in joining the Working Group on Reference Events for Improved Locations please email ryan@isc.ac.uk.
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This database of a significantly large number of reference events facilitates better visualisation of the Earth structure, better modelling of velocities of seismic waves, more accurate travel time determinations and increased accuracy of event locations. The events are coded by category GT0, GT1, GT2 or GT5, where the epicentre of a GTX event is known to within X km, to a 95% confidence level. GT1 and GT2 events are typically explosions, mine blasts or rock bursts either associated to explosion phenomenology located upon overhead imagery with seismically determined origin times, or precisely located by in-mine seismic networks. GT1-2 events are assumed to be shallow, but depth is unknown. The database consists of:
Download the IASPEI GT bulletin (gzip file) Download the IASPEI GT catalogue (gzip file) |
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References:
Bennett, T., Oancea, V., Barker, B., Kung, Y.-L., Bahavar, M., Kohl, B., Murphy, J., and Bondár, I. (2010) The nuclear explosion database NEDB: a new database and web site for accessing nuclear explosion source information and waveforms, Seismological Research Letters, Volume 81, doi:10.1785/gssrl.81.1.12.
Bondár, I. and K.L. McLaughlin (2009) A New Ground Truth Data Set For Seismic Studies, Seismological Research Letters, Volume 80, Number 3, 465-472.
Bondár, I., Engdahl, E., Yang, X., Ghalib, H., Hofstetter, A., Kirichenko, V., Wagner, R., Gupta, I., Ekström, G., Bergman, E., Israelsson, H., and McLaughlin. K. (2004) Collection of a reference event set for regional and teleseismic location calibration, Bulletin of the Seismological Society of America, Volume 94, 1528-1545.
Bondár, I., Bergman, E., Engdahl, E., Kohl, B., Kung, Y.-L., and McLaughlin, K. (2008) A hybrid multiple event location technique to obtain ground truth event locations, Geophys. Journal Int., Volume 175, doi:10.1111/j.1365,246X.2008.03,867x.
Gallacher, R., Garth, T., Harris, J., Bondár, I., McLaughlin, K., and Storchak, D. A. (In Review) Revising the Seismic Ground Truth Reference Event Identification Criteria, Seismica
Citation for data retrieved from the ISC web site:
International Seismological Centre (20XX), Preliminary IASPEI Reference Event (GT) List, https://doi.org/10.31905/A1CMX9W7
