We evaluated temporal and spatial variability of local magnitudes (ML) in the earthquake catalog of Alaska Earthquake Information Center. Regionally recorded hypocenters in mainland Alaska are available in the catalog beginning in the early 1970s. No comprehensive Aleutian-wide ML statistics exist prior to the mid-1990s. We identify four time intervals with similar magnitude residual trends between ML versus body-wave magnitude mb: 1971–1976, 1977–1989, 1990–1999.5, and 1999.5–2008. The three latter intervals are also identified in ML versus moment magnitude Mw residual trends. These time intervals correspond to the periods with different data processing procedures. We find that the latest time interval has the best correspondence between ML and Mw values in mainland Alaska, especially for shallow (depth<40 km) earthquakes. Strong spatial variations in ML versus mb and ML versus Mw are present in the catalog. For the pre-1990 data, the largest discrepancies are observed for the Gulf of Alaska earthquakes. For the latest time period 1999.5–2008, the largest residuals between ML and mb or Mw are observed for the earthquakes located within the oceanic segment of the Aleutian arc and within 100 km of the trench. We calculated a set of magnitude corrections for mainland Alaska and the Aleutians that need to be applied to homogenize magnitude values in the catalog in time and space.

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