USGS Volcano Hazards Program Volcano Update

YELLOWSTONE VOLCANO (CAVW#1205-01-)
44.43°N 110.67°W, Summit Elevation 9203 ft (2805 m)
Volcano Alert Level: NORMAL
Aviation Color Code: GREEN

June 2009 Yellowstone Seismicity Summary

During the month of June 2009, 77 earthquakes were located in the Yellowstone region. The largest event was a magnitude 3.3 on June 30 at 9:52 AM MDT, located about 15 miles east northeast of West Yellowstone, MT. This event was part of an ongoing small earthquake swarm that includes 25 events on June 30, beginning with the M3.3 The magnitudes during the swarm ranged from 3.0 to -0.2.

Earthquake activity in the Yellowstone region is at relatively normal background levels.

Ground Deformation Summary: Through June 2009, continuous GPS data show that uplift of the Yellowstone Caldera has slowed but may be continuing. The WLWY station, located in the northeastern part of the caldera, has undergone a total of ~23 cm of uplift since mid-2004. Its record can be found at: http://pboweb.unavco.org/shared/scripts/stations/?checkkey=WLWY&sec=timeseries_plots&timeseries=raw

The currently observed reduction in uplift rate may be related to seasonal changes related to snowmelt and groundwater recharge. In several of the past 5 years, such changes have caused decreased uplift or slight subsidence, but were followed later in the year by continued uplift. The general uplift of the Yellowstone caldera is of scientific importance and will continue to be monitored closely by YVO staff.

An article on the current 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