Andrew J. Michael 2014 <p>The International Seismological Centre, in collaboration with the Global Earthquake Model effort, has released a new global earthquake catalog, covering the time period from 1900 through the end of 2009. In order to use this catalog for global earthquake studies, I determined the magnitude of completeness (<i>M_c</i>) as a function of time by dividing the earthquakes shallower than 60 km into 7 time periods based on major changes in catalog processing and data availability and applying 4 objective methods to determine <i>M_c</i>, with uncertainties determined by non-parametric bootstrapping. Deeper events were divided into 2 time periods. Due to differences between the 4 methods, the final <i>M_c</i>&nbsp;was determined subjectively by examining the features that each method focused on in both the cumulative and binned magnitude frequency distributions. The time periods and <i>M_c</i> values for shallow events are: 1900-1917, <i>M_c</i>=7.7; 1918-1939, <i>M_c</i>=7.0; 1940-1954, <i>M_c</i>=6.8; 1955-1963, <i>M_c</i>=6.5; 1964-1975, <i>M_c</i>=6.0; 1976-2003, <i>M_c</i>=5.8; and 2004-2009, <i>M_c</i>=5.7. Using these <i>M_c</i> values for the longest time periods they are valid for (e.g. 1918-2009, 1940-2009,&hellip;) the shallow data fits a Gutenberg-Richter distribution with <i>b</i>=1.05 and <i>a</i>=8.3, within 1 standard deviation, with no declustering. The exception is for time periods that include 1900-1917 in which there are only 33 events with <strong>M</strong>&ge; <i>M_c</i> and for those few data <i>b</i>=2.15&plusmn;0.46. That result calls for further investigations for this time period, ideally having a larger number of earthquakes. For deep events, the results are <i>M_c</i>=7.1 for 1900-1963, although the early data are problematic; and <i>M_c</i>=5.7 for 1964-2009. For that later time period, <i>b</i>=0.99 and <i>a</i>=7.3.</p> application/pdf 10.1785/0120130227 en Seismological Society of America How complete is the ISC-GEM Global Earthquake Catalog? article