December 2009 Yellowstone Seismicity Summary
During the month of December 2009, 70 earthquakes were located in the Yellowstone National Park region. The largest event was a magnitude 2.2 on December 18 at 1:38 PM MST, located about 8 miles north northeast of West Yellowstone, MT. No earthquake swarms were recorded in December.
Earthquake activity in the Yellowstone region is at relatively normal background levels.
Ground Deformation Summary: Continuous GPS data show that uplift of the Yellowstone Caldera has slowed significantly and may have stopped. 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×eries=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