The University of Utah Seismograph Stations reports that a magnitude 4.4 earthquake occurred at 01:46 a.m. (MDT) on Thursday, August 21. The epicenter of the shock was located near Huckleberry Mountain in Wyoming, 8 miles southeast of the south entrance to Yellowstone National Park. The earthquake was reported felt in Yellowstone National Park at the south entrance and at Grant Village. It occurred in an area of relatively low seismicity. Those who felt the quake are encouraged to fill out a survey form on the Seismograph Stations web site: http://www.quake.utah.edu.

Please click here for a link to "Did you feel it?" The Community Internet Intensity Survey.

November 4, 2002 -- A major, magnitude-7.9 earthquake that rocked Alaska on Sunday apparently triggered scores of earthquakes some 2,000 miles away at Yellowstone National Park in Wyoming.

By 8:30 a.m. MST Monday Nov. 4 - about 17 hours after the Alaskan quake - more than 200 small earthquakes had been detected occurring in clusters throughout the Yellowstone area. The quakes were recorded by the Yellowstone seismic network operated by the University of Utah Seismograph Stations.

The smallest events were of magnitude less than 0 and the largest of about magnitude 2.5. National Park Service rangers at Old Faithful and Canyon Village reported feeling some of the earthquakes.

While the data are preliminary, they suggest that the Yellowstone earthquakes may have been triggered by the passage of large seismic waves generated by the Alaskan earthquake more than 3,200 kilometers (almost 2,000 miles) from the park. The apparent triggering is suggested by the fact the Yellowstone activity began within a half hour of the Alaska earthquake, which hit at 3:12 p.m. MST Nov. 3 (1:12 p.m. local time in Alaska).

There also are preliminary reports the Alaska quake may have triggered smaller tremors at The Geysers geothermal area in northern California.

Scientists once believed that an earthquake at one location could not trigger earthquakes at distant sites. But that belief was shattered in 1992 when the magnitude-7.3 Landers earthquake in California's Mojave Desert triggered a swarm of quakes more than 800 miles away at Yellowstone, as well as other jolts near Mammoth Lakes, Calif., and Yucca Mountain, Nev.

The apparent triggering of the Yellowstone tremors by the Alaska quake "confirms what we are beginning to see worldwide - that earthquakes can be triggered by other earthquakes at great distances, more so than we had thought before," said Robert. B. Smith, a University of Utah professor of geology and geophysics and coordinating scientist for the Yellowstone Volcano Observatory.

Clusters of small earthquakes in time and space are common in Yellowstone. However, the clusters of Yellowstone earthquakes following the Alaskan mainshock extended across much of the park and were not concentrated in a single location.

The small Yellowstone quakes are not considered to pose a threat to the public, but are of great interest to scientists who want to confirm if they were triggered and understand how. Investigation is ongoing and may take some time to complete, said Sue Nava, seismograph network manager at the University of Utah Seismograph Stations.

There has been some suggestion that seismic waves from a large, distant quake may jostle the ground at Yellowstone, triggering small quakes by moving the hydrothermal fluids responsible for Yellowstone geysers and hot springs.

Those wishing to view seismograms of the Alaska earthquake and those in Yellowstone recorded on the Yellowstone seismic network may go to the web site: http://www.seis.utah.edu/helicorder/heli/yellowstone/index.html

The U.S. Geological Survey's National Earthquake Information Center website has information on the Alaskan earthquake that can be viewed at: http://neic.usgs.gov/neis/bulletin/neic_lbbl.html

The Yellowstone seismic network is operated by the University of Utah Seismograph Stations as a partner in the Yellowstone Volcano Observatory (YVO). Information on YVO and earthquake activity in Yellowstone can be found at: http://volcanoes.usgs.gov/yvo/

The University of Utah Seismograph Stations reports that a magnitude 4.2 earthquake occurred at 9:20 p.m. MST this evening in Yellowstone National Park, Wyoming. The epicenter of the shock was located about 1 mile north of Norris Junction. The earthquake was reported felt at Madison Junction and a Mammoth, Wyoming in the northern region of Yellowstone National Park. No damage has been reported. The event is in an area that experienced an M 5.9 event in 1975 that caused damage and is located in an area noted for earthquake swarms.

Click here to access information about swarm activity in Norris Geyser Basin. For further information about this earthquake sequence, please contact Dr. Robert Smith, rbsmith@mines.utah.

The purpose of this press release is to alert the National Park Service and the pubic to a series of earthquakes occurring along the northwest edge of Yellowstone National Park. Earthquake activity in this area began notably increasing on Sunday evening, June 13, 1999. The earthquakes are located about 8 miles northeast of West Yellowstone, Montana, and about 3 miles southeast of Grayling Creek Junction, near Cougar Creek. As of Tuesday morning, June 22nd, over 630 earthquakes have been recorded in this region. The largest earthquake of the sequence (to date), a magnitude 3.5 shock, occurred on June 16th at 10:38 a.m. MDT. None of these earthquakes have been reported to our office as being felt by local residents.

The attached map shows the locations of this week's earthquake activity as well as the locations of earthquakes recorded since January 1, 1997. Geologically active faults and the northwest boundary of the Yellowstone caldera are also shown. This week's activity is located near mapped faults that extend eastward from the southern end of the devastating 1959 Hebgen Lake earthquake rupture. The magnitude 7.5 Hebgen Lake earthquake was the largest historic earthquake to occur in the Intermountain region.

(Right click here to save the attached postscript map to print later. Or view the attached map in GIF format.)

The tightly-clustered earthquakes, also referred to as an earthquake swarm, are a common occurrence in volcanic areas such as Yellowstone. This is the largest earthquake swarm to occur in Yellowstone National Park since June 1997, when a swarm occurred in the same general vicinity as the activity observed during the past week. Historically, the most persistent earthquake swarms in Yellowstone have occurred on the western side of the Park. The most extensive recorded earthquake swarm occurred about 6 miles southeast of the current activity over a period of several months in 1985 and 1986, with shocks as large as magnitude 4.5.

The University of Utah Seismograph Stations operates a 22-station seismograph network and a 2-station continuous-recording Global Positioning System network. This telemetered surveillance system provides coverage of Yellowstone National Park for earthquakes as well as ground movement that may be related to volcanic or earthquake activity. The project is conducted cooperatively with the U.S. Geological Survey Volcano Hazards Program and the National Park Service.

The University of Utah will continue to monitor the situation and alert the National Park Service and the public of any significant changes in earthquake activity. Information on earthquakes in the Yellowstone area is available from our Web site at: www.seis.utah.edu. Questions about this activity may directed to our offices at (801) 581-6274.