Volcano Information

    Yellowstone
    Volcanic Alert Level: NORMAL Aviation Color Code: GREEN

    • Current Update, last updated Aug 3, 2009 03:54 MDT:
      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
    • Volcanic History Overview: The Yellowstone Plateau volcanic field developed through three volcanic cycles spanning two million years that included some of the world's largest known eruptions. Eruption of the >2450 cu km Huckleberry Ridge Tuff about 2.1 million years ago created the more than 75-km-long Island Park caldera. The second cycle concluded with the eruption of the Mesa Falls Tuff around 1.3 million years ago, forming the 16-km-wide Henrys Fork caldera at the western end of the first caldera. Activity subsequently shifted to the present Yellowstone Plateau and culminated 640,000 years ago with the eruption of the >1000 cu km Lava Creek Tuff and the formation of the present 45 x 85 km caldera. Resurgent doming subsequently occurred at both the NE and SW sides of the caldera and voluminous (1000 cu km) intracaldera rhyolitic lava flows were erupted between 150,000 and 70,000 years ago. No magmatic eruptions have occurred since the late Pleistocene, but large phreatic eruptions took place near Yellowstone Lake during the Holocene. Yellowstone is presently the site of one of the world's largest hydrothermal systems including Earth's largest concentration of geysers.
    • Location: Western US, WY

      Latitude: 44.43
      Longitude: -110.67
      Elevation: 2805 m

      Recent Eruption:
    • Hazard Assessments: Christiansen, R. L., Lowenstern, J. B., Smith, R. B., Heasler, H, Morgan, L. A., Nathenson, M., Mastin, L. G., Muffler, L. J. P., and Robinson, J. E., 2007, Preliminary Assessment of Volcanic and Hydrothermal Hazards in Yellowstone National Park and Vicinity, U.S. Geological Survey Open-File Report 2007-1071.
    • Link to monitoring data:
      Recent earthquake activity in Yellowstone National Park (map and catalog with links)
      GPS Measured Horizontal Ground Motions
      Provisional real-time stream-flow data
      See the Yellowstone Volcano Observatory Monitoring Page for more.