Quality Assessment of the Reviewed Event Bulletin Through Comparison with the ISC Bulletin for the Month of October 2020 and Summary Results of Earlier Assessments

An attempt was made to assess the quality of the International Data Centre (IDC) Reviewed Event Bulletin (REB) by comparing it with the Reviewed bulletin of the International Seismological Centre (ISC). To accomplish the task of comparison, the ISC Reviewed Bulletin events as downloaded from the ISC Web page for the month of October 2020 were used. The corresponding REB events as listed in the ISC bulletin were considered. During this period, a total of 3431 and 2652 (excluding 39 Infrasound events) events were considered for ISC and IDC bulletins, respectively. The comparison was performed using the information given in the header lines of the ISC bulletin from which matched and unmatched events could be extracted. The results showed that a total of 2315 events could be matched between the two bulletins. The percentage of matched events with relative location difference (D) < 1° was about 95.3% while the percentage of events with D ≥ 5^o was about 0.35%. There were two potential events with IDC magnitude (mb) ≥ 4.0 and D ≥ 5°. The percentage of matched events with intersecting error ellipses was about 75.5%. Some results obtained from earlier studies which were produced by using similar approaches were also used in this study. In general, the results obtained in this study show that there was a slight difference when compared to the earlier comparison results.