Catalogue Overview, Version 11, 25 June 2024

On the 25th of June 2024, the version 11 of the ISC-GEM Catalogue was publicly released. The release marked the end of the second year of the ISC-GEM Improvement Project .

During this year we have reassessed 1,678 earthquakes during 1964-1970 after adding station data, particularly to improve their surface wave magnitude (MS) estimation. As result of the data added during 1964-1970 from stations bulletins, 642 earthquakes that occurred in these years are listed for the first time in the catalogue. Furthermore, the catalogue has been extended to the end of 2020, which now includes 1581 earthquakes with Mw down to 5.0 globally.

Details about changes to the catalogue are listed in the update log.

Fig. 1 shows the ISC-GEM locations with symbols according to Agnew (2014) as obtained from the procedure described in Bondár et al. (2015). One feature that makes the ISC-GEM Catalogue a unique product is that the locations are achieved by the same location technique and velocity model (ak135) and comes with uncertainties for each focal parameter.

Fig.1: map showing the earthquakes listed in the Version 11 of the ISC-GEM Catalogue (about 71,100 earthquakes, see also Fig.2). The symbols are plotted according to Agnew (2014) and colour coded according to the ISC-GEM depth.

Fig. 2 shows the current time-magnitude distribution of the ISC-GEM Catalogue (1904-2020).

Fig. 2: Top: cumulative annual number of earthquakes with Mw ≥ 5.0 (black), Mw ≥ 5.5 (red), ≥ 6.5 (blue) and ≥ 7.5 (yellow); Bottom: time-magnitude distribution color-coded in cells of 0.1 units of Mw for each year of the ISC-GEM main catalogue. For comparison with the original version see Fig. 20 in Di Giacomo et al. (2015b), or Figure 25 in Di Giacomo et al. (2018) for the comparison with Version 5.0.