ISC-GEM

Get the catalogue

Go to the ISC website and get the catalogue

The catalogue in a nutshell

The ISC-GEM Global Instrumental Earthquake Catalogue (1900-2009) features:

  • events with magnitude >= 7.5, occured between 1900 and 1917
  • events with magnitude >= 6.25, occured between 1918 and 1959
  • events with magnitude >= 5.5, occurred between 1960 and 2009

The catalogue is composed of earthquakes with homogeneous locations and magnitude estimates, determined using the same tools and techniques to the extent possible. The magnitude determination and location procedures applied represent a synthesis of state-of-the art methods.

Each event has a Mw value, the magnitude type currently used in the engineering seismology community, where possible based on seismic moment (mainly earthquakes in the period 1976-2009). In other cases new empirical relations have been used to obtain proxy values of moment magnitude. In the early instrumental era (1918-1959) the catalogue contains about 1900 earthquakes with magnitude instrumentally determined, against – for example – about 900 events currently available in the Abe catalogue.

Who developed it?

The International Seismological Centre led a team of international experts in the field. Dmitry Storchak coordinated the project, with scientific input from Willie Lee. In addition, observers from IASPEI (Peter Suhadolc and colleagues from Japan, Germany, United States and the United Kingdom) oversaw the whole process. You can read more about the team in the final report (see sidebar).

How is it of relevance?

Seismic Hazard Assessment

A reliable earthquake catalogue is a highly critical component in any type of seismic hazard analysis. Because earthquakes are low frequency, high-impact events, the history of past events is of great importance for characterizing the seismic hazard in an area. Historical data from descriptions of earthquake events is commonly combined with more accurate instrumental data from when the first seismological equipment started being used in the early 20th century.

Global

Only by working together on a global scale can earthquake hazard and risk assessment advance, as critical input for decisions to mitigate and reduce earthquake risk. The ISC-GEM catalogue provides a global starting point for continuous improvement of seismicity both for science and concrete applications.

What are its characteristics?

  1. It covers 110 years of seismic history. In many developing and emerging countries there is a lack of long-term instrumental recordings and this catalogue currently offers the only long-term record of seismicity for calculating seismic hazard.
  2. It is a truly instrumental catalogue in which the main earthquake parameters (location, depth and magnitude) are re-calculated based on the basic parametric seismogram readings of quality seismic stations worldwide.
  3. It is homogeneous to a high degree, because the main earthquake parameters are calculated based on the same procedure. As a result, one can with a much higher degree of confidence than before compare the earthquake location and magnitude values in the first and second part of the 20th century.
  4. The main earthquake parameters are furnished with estimates of uncertainty. Such information is not available in current catalogues. Uncertainty estimation improves the accuracy of (subsequent) seismic hazard assessment.
  5. The magnitude computations, especially in the first part of 20th century, are based on a wealth of large new volumes of surface wave amplitude readings that were not globally available prior to this work.
  6. Seismicity patterns are clustering out to reveal much finer earthquake occurrence structures that in view of earthquake’s self-repeating principle are seen as a confirmation of improved location of the event(s).
  7. The ISC-GEM Catalogue can be used as reference for regional efforts of creating earthquake history. Basic parameters of moderate events in the regional catalogues will be calibrated based on those of ISC-GEM, creating vertical (in earthquake size) and lateral (between regions) homogeneity worldwide.
  8. The approach taken in construction and compilation of this catalogue can be used as a model for regional efforts.
  9. It provides references to all original sources, including scanned historical bulletin pages.
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How is it different?

  • It comprises more events than current global instrumental catalogues
  • It goes far beyond a compilation and combination of existing catalogues, magnitudes have been recomputed using original amplitudes
  • It includes uncertainty estimation
  • It follows a standard methodology that is well documented and can be used and applied for regional catalogues
  • It combines knowledge and resources from around the globe and benefited from unique collaboration with scientists working on related topics, such as active faults
Hundreds of bulletins were processed for inclusion in the catalogue

Hundreds of bulletins were processed for inclusion in the catalogue

Magnitudes are as much as possible featured as Mw values

Magnitudes are as much as possible featured as Mw values

A great number of earthquakes was relocated

A great number of earthquakes was relocated

How can I use it?

The catalogue is available from the ISC website and will become part of the OpenQuake Platform.

There is a CSV version plus an appendix with earthquakes that were omitted from the catalogue because of poor data quality.

The catalogue (csv-file) comprises the following information:

  • earthquake origin, data and time
  • epicenter (latitude, longitude)
  • error ellipse parameters (smajax, sminax, strike), epicenter quality (q: A(highest)/B/C)
  • depth, depth uncertainty (unc), depth quality (q: A(highest)/B/C)
  • Mw, Mw uncertainty (unc), quality (q: A(highest)/B/C), source (s:p-proxy, d-direct computation)
  • where available: scalar moment (mo), factor (fac), mo author (mo_auth)
  • where available: six moment tensor components (mpp, mpr, mrr, mrt, mtp, mtt)
  • ISC numerical event identificator

In addition there is a kmz-file to explore the catalogue with Google Earth as you can see in the video above. 

Copyright and Licensing

Versions 1.00, 1.01, 1.02 and 1.03 of the ISC-GEM Global Instrumental Earthquake Catalogue and Appendix to the Catalogue were released under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0).

Version 1.04, released on 5th November 2013, was instead released under the terms of the Creative Commons Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0).

To learn more see GEM licensing page.

How can I contribute?

The global project to produce a v1.0 of a global instrumental earthquake catalogue has now ended, but we are keen to hear from you at any time... 

  • in case you possess or know of studies that could enhance the catalogue for specific earthquakes
  • about your experiences using the catalogue
  • for any other idea or questions

Send an email to hazard@globalquakemodel.org or use the site contact form.