Small magnitude earthquake rates have been steadily increasing since March, reaching nearly 40 per week.
5 May 2016 – (Excerpts from USGS website) – Over the last 8 weeks, there have been over 130 earthquakes formally located by the Pacific Northwest Seismic Network and many more earthquakes too small to be located. The earthquakes have low magnitudes of 0.5 or less; the largest a magnitude 1.3. These earthquakes are too small to be felt at the surface.
Such events are commonly seen in active hydrothermal and magmatic systems.
The current pattern of seismicity is similar to swarms seen at Mount St. Helens in 2013 and 2014; recharge swarms in the 1990s had much higher earthquake rates and energy release.
There are no signs of an imminent eruption.
As was observed at Mount St. Helens between 1987-2004, recharge can continue for many years beneath a volcano without an eruption.
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