Aleutian Quake Goes from 7.5 to 6.2 to 6.6

The USGS reported a large earthquake in the western Aleutian Islands late Saturday morning local time. The initial local magnitude M_l was 7.5, but soon the authorities calculated a more robust moment magnitude M_w of 6.2. Three days later, the USGS refined the measurement to 6.6. Typically, this area has thrust events directed to the northwest, as was Saturday's quake. The area is not very well instrumented, so it takes collation of more distant seismograms to home in on a decent magnitude determination. Follow developments on the U.S. Geological Survey's special page for this quake.