# Expanding Moment Magnitude Pools for Earthquake Magnitude Homogenization
## 3 Results
### South Korea  
A map showing the epicenters of the search results is shown in Figure 9, suggesting low seismicity in the region. There are a total of 1544 events in the South Korean catalog with major contributions from ISC, KMA, JMA, and NIED. South Korean-related earthquakes with NEIC moment magnitudes are plotted in Figure 10, demonstrating the general sparsity of events available to compile a catalog, especially in comparison to the Indonesian catalog compiled herein. On the other side, Figure 11 shows KMA recorded many low magnitude events in the Korean peninsula since its inception in 1978. Figure 8: Resultant magnitude homogenization regressions for M\({}_{\text{W,GCMT-related}}\) against (**a**) M\({}_{\text{L,DJA}}\), (**b**) M\({}_{\text{D,DJA}}\), and M\({}_{\text{W,GCMT-hypothesis}}\) against (**c**) M\({}_{\text{I,V,DJA}}\). Data from M\({}_{\text{W,GCMT}}\) are also shown. Black line is the regression against M\({}_{\text{W,GCMT-related}}\) or M\({}_{\text{W,GCMT-hypothesis}}\) while the dashed red line is the regression against M\({}_{\text{W,GCMT}}\). Figure 11: Local magnitude from KMA and moment magnitude types from Japanese sources, and timeframes when they are valid in the South Korean catalog. Figure 9: Epicenters of earthquakes in the compiled catalog for South Korea. A tally of the different magnitude types is shown in Table 7. To present a more concise tally, all types of moment magnitude are listed under M\({}_{\rm W}\) and all surface wave type magnitudes for NEIC are listed under M\({}_{\rm S}\). Relative to Indonesia, there are significantly fewer earthquakes to consider for catalog development. Understandably, there are no EVBIB events recorded for South Korea. Moreover, relative to international agencies, there are notable record contributions from local and regional Japanese agencies, JMA and NIED. The table shows the initial number of earthquakes recorded under M\({}_{\rm W,GCMT}\) is 15. The number of earthquakes in the M\({}_{\rm W,GCMT-related}\) Pool is 17, with additions of 2 and 0 events from ISC-GEM and HRVD, respectively. Although HRVD should not be considered in this study due to the low number of events, it is shown here only for completeness as it is relevant to GCMT-related studies. Note EVBIB did not appear in search results. The initial base of the M\({}_{\rm W,GCMT-hypothesis}\) pool contained 17 earthquakes from GCMT and ISC-GEM (GCMT and bibliographic sources). After hypothesis testing, the number increased to 20, with contributions from NEIC and JMA, the only sources that did not reject the null hypotheses with more details shown in Table 8. The contributions from HRVD are superseded by records in GCMT. In terms of NEIC moment magnitudes, the table shows that only the M\({}_{\rm WW}\) and M\({}_{\rm WR}\) magnitude types had significantly similar slopes and intercepts to a one-to-one line. Note that there are no M\({}_{\rm WC}\) records in the search results. The test results show two and one events being added from JMA M\({}_{\rm W}\) and NEIC M\({}_{\rm WR}\), respectively. The resultant magnitude homogenization regressions for all surface wave magnitude types considered herein, i.e., M\({}_{\rm S,IEC}\), M\({}_{\rm S,NEIC}\), M\({}_{\rm S20,NEIC}\), M\({}_{\rm SZ,NEIC}\), are shown in Table 9. The results show little variation when considering different moment magnitude pools for M\({}_{\rm S,IEC}\) and M\({}_{\rm S,NEIC}\), where the moment magnitude pools for M\({}_{\rm S,NEIC}\) did not differ from a GCMT base. Although regressions with M\({}_{\rm S,NEIC}\) resulted in very low \(\sigma\), they also used very little data for regression. Unfortunately, there are not enough data pairs for M\({}_{\rm S20,NEIC}\) and M\({}_{\rm SZ,NEIC}\) to perform meaningful magnitude homogenization regression.