Catalogue Update Log

31 Jan, 2013: Version 1 released

This was the first public release of the Catalogue following the completion of the 27 months project.

26 Feb, 2013: Version 1.01 released

Updated the Mw and Mw proxy values of eight large earthquakes (evids 906508, 897799, 895348, 863756, 830410, 825732, 795586, 736783) following an additional review of corresponding scientific articles and correcting typographic errors in the results of the original bibliographical search for reliable seismic moments. In particular, we thank
Dr. Alexey Ivashchenko from the Tsunami Lab of the Institute of Oceanology, Russian Academy of Sciences, Moscow for pointing out an erroneous Mw for the Mondy earthquake (Baikal rift zone) of April 4, 1950 (evid = 895348).

1 May, 2013: Version 1.02 released

Updated are the Mw proxy values for 84 earthquakes between 1988 and 2009. The Mw proxies were based on excessively large MS based on the surface wave amplitudes reported by just a few stations or a single agency. The updated Mw proxies are now based on mb. In particular, we thank Helene Lyon-Caen and colleagues from the Laboratoire de Géologie, Ecole Normale Supérieure in Paris, for pointing out the large Mw proxies for two earthquakes in Greece.

11 June, 2013: Version 1.03 released

Updated the location for the earthquake occurred near coast of Venezuela the 1929-01-17 (evid = 907860) and the Mw for the 1967-07-30 Caracas earthquake (evid = 833882). The new location for the 1929-01-17 earthquake is about 98 km north the previous one and fits better with the tsunami observation for this event. The Mw = 7.0 for the 1967-07-30 Caracas earthquake initially adopted from Rial (JGR, 1978) has been replaced with a more recent determination of Mw = 6.6 by Suárez and Nábělek (JGR, 1990). We thank Michael Schmitz and Herbert Rendon from the Applied Geophysics Department, Fundación Venezolana de Investigaciones Sismológicas (FUNVISIS), for inquiring about the location and magnitude of these earthquakes.

5 November, 2013: Version 1.04 released

We noticed that the Appendix is not recognised by our users as an important part of the ISC-GEM Catalogue. We therefore renamed the Appendix to be called Supplementary Catalogue.

The terms of the license have also changed to reflect the availability of the ISC-GEM Catalogue to all parties.

Updates to the catalogue regard 1) the proxy Mw for the 12 April, 1967 earthquake in the Leeward Islands region (evid = 836598) and 2) the GCMT solution for the complex event occurred near Potenza (South Italy) the 1990-05-05 (evid = 368231). With regard to the Leeward Islands 1967 event the original proxy Mw = 7.4 was based on the MS from three mis-associated station amplitude readings. The updated proxy Mw 5.0 is based on mb. We thank Uri Ten Brink from USGS office in Woods Hole, MA, for pointing out the excessive magnitude value. With regard to the complex Potenza earthquake of 1990-05-05, the GCMT solution has been moved to evid = 368231 from evid = 368230. These two events are separated by approximately 10 seconds and are interpreted as foreshock (evid = 368230) and mainshock (evid = 368231). For more details see, e.g., Ekström (1994). Since the magnitude estimates for the foreshock are uncertain, evid = 368230 is now listed in the Supplementary Catalogue. We thank Paolo Harabaglia (University of Basilicata, Potenza, Italy) for drawing our attention to these events and Göran Ekström (Lamont-Doherty Earth Observatory of Columbia University, USA) for discussing the association of the GCMT solution.

14 February, 2014: Version 1.05 released

Updates to the catalogue regard 1) updated location and magnitude of the earthquake in Sumatra that occurred the 6 June 1943 (evid = 899872), which moved from the Supplementary Catalogue to the Main Catalogue; 2) updated the proxy MW for six earthquakes; 3a) addition of an earthquake (evid = 603952288) in the Main Catalogue that occurred in Turkey the 4 December 1905 and 3b) updated location of one of its aftershocks (evid = 16957879) that occurred approximately five hours later.

Details follow:

1) The location of the 6 June 1943 Sumatra earthquake has been updated and the epicentre moved to the North 40 km but most importantly the depth changed from 90 to a fixed depth of 10 km. Although the reported depth phase arrival times suggest that the hypocentre is around 90 km, we accept the 10 km depth since surface ruptures were reported (see, e.g., Untung et al., BSSA 1985). Hence, the event now moved from the Supplementary Catalogue to the Main Catalogue as with the shallow depth solution MS is available. From 12 stations we obtain MS= 7.8 +/- 0.1, which lead to a MW proxy of 7.81 +/- 0.25. We thank James Dewey (USGS Emeritus) for drawing our attention to this event.

2) the proxy MW for six earthquakes (evid 679878, 1656088, 1656090, 1728632, 13389548, 11911358) has been updated. With the exception of evid = 679878, the proxy MW is now based on mb instead of MS. The MS for those earthquakes was based on few stations with suspiciously large amplitudes. For evid = 679878 we obtained a new MS after correcting the surface wave amplitude units at six stations from micrometers to nanometers. The new six MW proxies are significantly smaller than the previous ones.

3a) the mainshock of the East Anatolian Fault sequence that occurred the 4 December 1905 has been added (evid = 603952288) after collecting arrival times from the ISA bulletin (61 arrivals) and surface wave amplitudes from four stations (GTT, LEI, POT, JEN). The event was missing due to a mis-association in the Centennial Catalogue between magnitude and origin time of the mainshock with one of its aftershocks;
3b) the location of the aftershock at 12h (evid = 16957879), which was already available in previous releases, has been updated. The previous ISC-GEM location was close to Aleppo, Syria, whereas the current location is much closer to the East Anatolian Fault.

19 January, 2015: Version 2.0 released

Version 2.0 of the ISC-GEM Catalogue is the result of the 1st year of the Extension project that began in November 2013. We included earthquakes smaller than 6.25 from the 1950s, listed in the ISS but not processed by us in the past. We also included earthquakes that occurred in 2010 and 2011. The recent data were available from the ISC Bulletin in an electronic format, but the arrival time data for earthquakes in the 1950’s had to be digitized from the ISS and amplitude-period data added in order to re-assess the magnitudes (mostly MS), using procedures described in Di Giacomo et al. (2014).

Version 2.00, therefore, now includes data for 504 earthquakes from 2010 and 672 from 2011. For the 1950s, we processed and relocated 4156 earthquakes and obtained 2216 new MS and 12 mb values. We also introduced a new magnitude quality flag “D” for the Mw proxies with uncertainty larger than 0.7, which is now listed in the Supplementary Catalogue. In addition, since many ISS earthquakes during the 1950s when processed resulted in MS smaller than 5 (i.e, much smaller than our catalogue cut-off magnitude of 5.5), we have listed them in the Supplementary Catalogue rather than excluding them completely from the Catalogue, with particular regard to the importance of re-assessing the magnitude of earthquakes before the beginning of the digital era.

During the year we also received station bulletins kindly provided by colleagues from Edinburgh, Eskdalemuir, Obninsk, Prague and Apatity. Those station bulletins helped us to fill some significant gaps in the ISCs original collection and allowed us to add new amplitude-period data for earthquakes listed in previous versions of the ISC-GEM Catalogue. With the data newly available, we obtained fresh magnitudes for about 200 earthquakes that were previously listed in the Supplementary Catalogue (Version 1.05) and added 237 new earthquakes between 1960 and 1963. Finally, we revised the hypocentre locations of 458 earthquakes in the catalogue, predominantly in remote areas, with 75% of depth changes within 20km and the rest within 60km.

10 July, 2015: Version 2.01 released

Removed evid = 877612 from the main catalogue as the event is a documented nuclear explosion in Novaya Zemlya.