Yellowstone Monthly Update issued May 3

During the month of April 2010, 117 earthquakes were located in the Yellowstone region. The largest event was a magnitude 3.3 on April 3rd at 9:15 PM MDT, located about 7 miles east southeast of West Yellowstone, MT. This event was part of a swarm which lasted from April 1st to the 7th. The swarm contained 52 earthquakes, with magnitudes 0.4 to 3.3. This latest swarm is considered part of the intense January/February Madison Plateau 2010 earthquake swarm that contained more than 2,300 earthquakes. A summary of the Madison Plateau swarm can be found at: http://volcanoes.usgs.gov/yvo/publications/2010/10swarm.php

Earthquake activity in Yellowstone continues at background levels.

Ground Deformation Summary: Continuous GPS data show that uplift of the Yellowstone Caldera has slowed significantly. Uplift rates for YVO GPS stations are less than 2.5 cm per year. The WLWY station, located in the northeastern part of the caldera, underwent a total of ~23 cm of uplift between mid-2004 and mid-2009. Its record can be found at: http://pboweb.unavco.org/shared/scripts/stations/?checkkey=WLWY&sec=timeseries_plots&timeseries=raw

The general uplift and subsidence of the Yellowstone caldera is of scientific importance and will continue to be monitored closely by YVO staff.

An article on the recent uplift episode at Yellowstone and discussion of long-term ground deformation at Yellowstone and elsewhere can be found at: http://volcanoes.usgs.gov/yvo/publications/2007/upsanddowns.php