Yellowstone Volcano Update

YELLOWSTONE VOLCANO OBSERVATORY MONTHLY UPDATE
Monday, August 3, 2009 15:54 MDT (Monday, August 3, 2009 21:54 UTC)


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

July 2009 Yellowstone Seismicity Summary

During the month of July 2009, 98 earthquakes were located in the Yellowstone region. The largest event was a magnitude 2.7 on July 8 at 9:08 AM MDT, located about 5 miles south southeast of Fishing Bridge, WY. The swarm that began on June 30th continued through July 3. This small swarm was located about 15 miles east northeast of West Yellowstone, MT and totaled 37 earthquakes with magnitudes ranging from 3.3 to -0.2.

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

Ground Deformation Summary: Through July 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

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The Yellowstone Volcano Observatory (YVO) is a partnership of the U.S. Geological Survey (USGS), Yellowstone National Park, and University of Utah to strengthen the long-term monitoring of volcanic and earthquake unrest in the Yellowstone National Park region. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world and the first National Park. YVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety.