# Expanding Moment Magnitude Pools for Earthquake Magnitude Homogenization
## 2 Materials and Methods  
### Earthquake Catalog Construction  
Several global sources will be used to construct Indonesian and South Korean earthquake catalogs for examination. The focal earthquake data source is the Global Centroid-Moment-Tensor (GCMT) Project [9]. This catalog contains events with M\({}_{\rm W}\) from centroid moment tensor solutions and as such is considered the most reliable source of M\({}_{\rm W}\) records [3; 10; 11; 12]. Records start from 1976. Prior to 2006, GCMT was previously known as the Harvard CMT Project.  
Another important seismological agency is the International Seismological Centre (ISC). The ISC houses a global earthquake catalog called the Reviewed ISC Bulletin, containing data from a variety of seismological agencies and projects since 1900 [13; 14; 15; 16]. Each seismological agency or project that submits data to the ISC is identified by a code, for example, the Harvard CMT Project is identified as HRVD. Although several seismological agencies and projects submit M\({}_{\rm W}\) records to the ISC Bulletin, the ISC itself currently does not record or compute a M\({}_{\rm W}\) magnitude type in the ISC Bulletin. However, the ISC houses a M\({}_{\rm W}\) catalog called the ISC-GEM Global Instrumental Earthquake Catalogue (ISC-GEM). This catalog contains three kinds of earthquake events: (i) those published by GCMT, (ii) M\({}_{\rm W,proxy}\) estimates from re-computed M\({}_{\rm S}\) and m\({}_{\rm b}\) records, and (iii) events taken from literature [17; 12; 18; 19].  
Another global agency, the United States Geologic Survey National Earthquake Information Center, USGS NEIC, has submitted earthquake records to the ISC Bulletin since 1980 [20; 21]. The ISC Bulletin also contains older NEIC data, when it was known as the National Earthquake Information Service, NEIS. The USGS also works with a variety of seismic networks such as the U.S. Geological Survey, GS, Coast and Geodetic Survey of the United States CGS, and the United States Coast and Geodetic Survey, USCGS that also contribute to the ISC Bulletin. For ease of use, recordings from USGS networks will be classified under the heading of NEIC. Unlike the ISC, the NEIC does publish CMT-based M\({}_{\rm W}\)s in their bulletins [10; 11; 21; 22].  
Two local seismological agencies will be used, one for Indonesia and one for South Korea. The Indonesian agency, Badan Meteorologi, Klimatologi dan Geofisika, DJA, which previously went by the identifier of BMKG, offers a variety of magnitude types, in the ISC Bulletin. The South Korean agency, Korea Meteorological Administration, KMA, mostly offers M\({}_{\rm L}\) although the local magnitude scale calibration had some issues [4; 23; 24].  
A search of the catalogs is limited to a zone that extends 200 km away from each country's borders and 50 km deep. For Indonesia, this zone is approximated by coordinates 95\({}^{\circ}\) E to 141\({}^{\circ}\) E and 11\({}^{\circ}\) S to 6\({}^{\circ}\) N. For South Korea, this zone is approximated by 122\({}^{\circ}\) E to 134\({}^{\circ}\) E and 31\({}^{\circ}\) N to 41\({}^{\circ}\) N. Data up to 2020 will be considered. There will be no distinction between main shocks, foreshocks, and aftershocks. With no distinction between dependent events and a compilation from multiple catalogs, there is a potential for duplicates in the resultant catalogs. For this study, two events are classified as duplicates if the time of occurrence is within 30 s of each other and within an epicentral distance of 0.1\({}^{\circ}\). In case of duplicates, data from global catalogs take precedent over local regional catalogs in the order of GCMT, ISC-GEM, ISC, and NEIC [3; 11; 12], with all magnitude types assigned to the final entry.