General comments

The manuscript gives an overview of moment magnitudes (Mw) that are reported for earthquakes globally and compiled at the ISC into their bulletin. The majority of Mw are reported by global monitoring centers, i.e. the NEIC and GCMT. The authors point out the importance of the ISC catalog with the Mw reports for many geophysical and seismological studies and applications. The particular focus in this work is to investigate and highlight the Mw contributions from other data centers that operate at either regional or global scale. The main conclusions from the work are: 1) the ISC bulletin with the integrated Mw reports is a very valuable resource; 2) complementing the global Mw reports with more regional reports allows to extend the bulletin (with Mw) to smaller magnitude; 3) reports of Mw for smaller earthquakes are still limited and observatories are encouraged to report. The manuscript provides a comprehensive overview of currently available Mw measurements. However, the authors avoid explaining possible discrepancies seen in the reports from the various agencies that may come from using different methods.

Specific comments

The manuscript is generally well written and easy to follow. The authors are inclusive and consider all possible agencies that are reporting Mw. However, the text would be easier to read by moving text on data sources that provide too few Mw reports (and are not much used in the study) to supplementary material.

While Mw is well covered in the literature, the authors could add a couple of sentences on the basic methodology used by GCMT to obtain the seismic moment, which would be useful for the non-seismologist. It also would be useful to mention limitation of Mw in not being sensitive to energy release.

The authors avoid providing details on how Mw is measured by the smaller agencies. I think it would be important to at least explain that the methodology may change when going from large to small earthquakes (where moment tensor inversion may no longer be the method that is used). Ideally, the manuscript would benefit to at least give an indication of what is done by the institutions at the regional scale, perhaps in form of a table, as this is needed to even partly understand some of the observations that are made when comparing global and regional Mw. It is also possible that Mw is the outcome of a standard automatic procedure – in that case it would be useful if and how the results are revised.

The authors explain that NEIC reports Mw provided by other agencies and these are labelled. I am concerned if the other way around, regional agencies may also provide Mw that they took from NEIC/GCMT. There may be no issue at all, but if there was the comparison would not be meaningful for those agencies.

The authors appear to be using MS and mb to compare to regional Mw, this may require better justification. It also could be an alternative not to include non-Mw magnitudes in this work.

It is appreciated that the authors provide the data and scripts for plotting.

Technical suggestions

More detailed comments on content and language are given in the attached PDF.

Comments to “Complementing regional moment magnitudes to GCMT: a perspective from the rebuilt ISC Bulletin”

Relevant and interesting description of a precious dataset such as the ISC in general, not only for magnitudes.

The comparison of GCMT Mw with so many agencies shows the remarkable consistency of the characteristics regardless of the region covered by the data from the regional agencies. It would be nice to have a description, even a short one, of the different methods used in the different agencies to get the Mw.

This work also shows how important it is to produce data consistently along time. Long time window of data availability allows to find strong relationships between different magnitudes, necessary to standardize and increment dataset constituted by different magnitudes and produced with different methods/authors. This kind of dataset are fundamental for hazard studies for instance. It is appreciated also the invitation written clearly by the authors to observatories and regional agencies to produce data with constancy in time, as long as possible.

Some comments (also reported in the pdf) are the followings:

1) Some of figures have to be modified, mainly maps of events because those with lower seismicity are mostly not visible. Probably an inversion of the plotting order avoid that bigger simbols overlap smaller ones.

2) It would be really interesting, when possible, to add in the M comparison plots also other relation curves (e.g. the Borman et al 2013 or Lolli et al 2014 or else?)

I recommend also a review of the language.