USGS Volcano Hazards Program Volcano Update
Recent Observations: An M 2.4 earthquake occurred beneath the summit of Mount Rainier at 08:45 PDT, September 13, and was followed by a dozen or so aftershocks over the next ~20 minutes. According to the Pacific Northwest Seismic Network (http://pnsn.org), the M 2.4 earthquake was located beneath the north rim of East Crater at a depth of ~2.7 km. Such earthquakes, while not common, are also not unprecedented at Mount Rainier -- M > 2 earthquakes occur about once per year on average below the Rainier summit, with the most recent being an M 2.9 on October 14, 2011, and an M 2.2 on October 25, 2011. The location and depth of the the 09/13/2012 M 2.4 earthquake are entirely consistent with past Rainier earthquakes, and such events are considered by CVO and the PNSN to be part of the background "normal" level of activity at Mount Rainier.
The U.S. Geological Survey Cascades Volcano Observatory and the University of Washington continue to monitor the Washington and Oregon volcanoes closely and will issue additional updates and changes in alert level as warranted.
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Update in Common Alerting Protocol (CAP) format