Madison Plateau 2010 Earthquake Swarm Summary

Calculations, by the University of Utah Seismology Research Group, of the total seismic energy released by all the swarm earthquakes corresponds to one earthquake with an approximate magnitude of 4.4. The largest recorded swarm at Yellowstone remains the Fall 1985 swarm, which was located in a similar location, in the NW corner of the Yellowstone Caldera.

As of April 6, 2010 a total of 2,347 earthquakes had been automatically located for the entire swarm, including 16 with a magnitude greater than 3.0; 141 with M2.0-2.9; 742 with M1.0-1.9; and 1,361 with M0.0-0.9. The largest events were a pair of earthquakes of magnitude 3.7 and 3.8 that occurred after 11 PM MST on January 20, 2010. Both events were felt throughout the park and in surrounding communities in Wyoming, Montana, and Idaho.

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See the University of Utah Seismograph Stations for the most recent earthquake data. Analysts continue to work through all the automatic earthquake locations, and are refining hypocenter locations, depths and magnitudes for inclusion in the earthquake catalog. As the events are refined, they are listed on the UUSS website and loaded into the ANSS catalog . Seismograph recordings are also available online by clicking on the station of interest on the Yellowstone seismograph network station map.

Swarms are common at Yellowstone

The number of earthquakes per day throughout the swarm was well above average at Yellowstone. Nevertheless, swarms are common at Yellowstone, with 100s to 1000s of events, some of which can reach magnitudes greater than 4.0. There were about 900 earthquakes during the December 2008 - January 2009 Yellowstone Lake swarm. The largest earthquake was a magnitude 3.9. The 1985 swarm, also on the northwest rim of the caldera but several miles from the current swarm, lasted for three months. During the 1985 swarm there were over 3000 total events recorded, with magnitudes ranging up to M4.9.

Although we give earthquake counts for previous swarms, it is not strictly correct to compare small differences in the number of earthquakes from one swarm to another. The number of earthquakes located depends on how close the earthquakes are to the monitoring equipment, the type and number of the seismometers in the network, and the software for analyzing the earthquakes. Our current monitoring capabilities allow for us to record many more earthquakes than we recorded in 1985, especially on the lower end of the magnitude scale. Even in the past year, the difference in the swarm locations and a change in software used to analyze the earthquakes makes it difficult to directly compare the earthquake count from last year's Yellowstone Lake Swarm to the current swarm. However, the earthquake count is still a useful number, especially for comparing the number of earthquakes from a swarm to other days during that year.

Seismologists Continue to Review the Earthquakes

Earthquakes with magnitudes greater than 2.5 are automatically located and then automatically plotted on the University of Utah Map of Recent Earthquakes. The smaller events must be analyzed by a seismic analyst who determines which are the correct earthquakes from a specific area. Because the smaller events need to be individually located, they are added to the map later than those that are automatically located. The delay in reporting the smaller earthquakes is usually not very noticeable, except when there are large numbers of very small earthquakes. The smaller earthquakes can be viewed on the University of Utah Yellowstone seismic network helicorders. Please keep in mind that all of the earthquakes will be analyzed but it will take time to get to the smaller ones.

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We Continue to Monitor Yellowstone Volcano

YVO staff from the USGS, University of Utah, and Yellowstone National Park continue to carefully review all data streams that are recorded in real-time. At this time, there is no reason to believe that magma has risen to a shallow level within the crust or that a volcanic eruption is likely. Yellowstone National Park is in a region of active seismicity associated with regional Basin and Range extension of the Western U.S., as well as volcanism of the Yellowstone volcanic field. Pressurization due to crustal magma bodies of the Yellowstone hotspot and associated shallow geothermal reservoirs can also contribute to earthquakes. Scientists continue to research the origin of these and other Yellowstone earthquakes.

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.

Other items of interest

• Although the current swarm was not triggered by a large earthquake such as the January 12, 2010 M7.0 Haiti earthquake, in Nov 2002 there was a swarm of earthquakes at Yellowstone that were triggered by the Nov 3, 2002 Denali earthquake. See the University of Utah Press Release: Alaska Quake Seems to Trigger Yellowstone Jolts Small Tremors Rattle National Park After Big Quake 2,000 Miles Away. And the later release in May 2004: Quake in Alaska Changed Yellowstone Geysers