YELLOWSTONE VOLCANO OBSERVATORY MONTHLY UPDATE
Friday, May 1, 2009 11:17 MDT (Friday, May 1, 2009 17:17 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

April 2009 Yellowstone Seismicity Summary

During the month of April 2009, 242 earthquakes were located in the Yellowstone region. The largest event was a magnitude 2.7 on April 28 at 7:14 PM MDT, located about 6 miles north northeast of Old Faithful, YNP. A second M 2.7 was part of a swarm detailed below. There were three earthquake swarms during the month of April. The first, located 4 miles northwest of West Yellowstone, included 62 events spanning April 13-18 with magnitudes ranging from 1.3 to -0.6. The second, located 7 miles northwest of West Yellowstone, included 111 events from April 17-24 with magnitudes 2.3 to -0.8. The third swarm, located 11 miles northeast of Old Faithful, included 19 events all occurring on April 29th with magnitudes ranging from 2.7 to 0.5.

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

An article on the recent earthquake swarm during December 2008 and January 2009 can be found at:
http://volcanoes.usgs.gov/yvo/publications/2009/09swarm.php
Scientists continue to look at data collected during the swarm and will publish their results over the coming months and years. However, if any findings have direct implications for public safety, they will be released to the public immediately.

Ground Deformation Summary: Through April 2009, continuous GPS data show that much of the Yellowstone caldera continued moving upward, though at a lower rate than the past several years. The WLWY station, located in the northeastern part of the caldera has undergone ~23 cm of uplift since mid-2004. 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.