Yellowstone Earthquake Swarm Summary as of 30 January 2010
Map of Yellowstone National Park showing recent swarm earthquakes in red,
previous swarms from 1995-2009 in green, and volcanic vents with yellow
stars. Caldera boundaries are shown in orange. Mallard Lake Resurgent dome,
to the southwest, and Sourcreek Resurgent dome, to the northeast, are shown
with yellow lines. The histogram at the top right shows the number of
earthquakes per day from January 15 to January 28. Image by Jamie Farrell
and Robert B. Smith (University of Utah), data from the University of Utah
Seismograph Stations. Click on the image for a full-size version.
As of January 30, 2010 9:00 AM MST there have been 1,585 located earthquakes in the recent Yellowstone National Park swarm. The swarm began January 17, 2010 around 1:00 PM MST about 10 miles (16 km) northwest of the Old Faithful area on the northwestern edge of Yellowstone Caldera. Swarms have occurred in this area several times over the past two decades.
There have been 13 events with a magnitude larger than 3, 114 events of magnitude 2 to 3, and 1458 events with a magnitude less than 2. The largest events so far have been a pair of earthquakes of magnitude 3.7 and 3.8 that occurred after 11 PM MST on January 20, 2010.
The first event of magnitude 3.7 occurred at 11:01 PM MST and was shortly followed by a magnitude 3.8 event at 11:16 PM. Both shocks were located around 9 miles to the southeast of West Yellowstone, MT and about 10 miles to the northwest of Old Faithful, WY. Both events were felt throughout the park and in surrounding communities in Wyoming, Montana, and Idaho.
See the University of Utah Seismograph Stations for the most recent earthquake data and press releases. The team is working 24/7 to analyze and communicate information about the swarm. Seismograph recordings from stations of the Yellowstone seismograph network can be viewed online at: http://quake.utah.edu/helicorder/yell_webi.htm.
Swarms are common at Yellowstone
The current number of daily earthquakes is well above typical daily earthquake activity at Yellowstone. Nevertheless swarms are common at Yellowstone, with magnitudes occasionally above 4.0. There were about 900 earthquakes during the December 2008 - January 2009 Yellowstone Lake swarm. 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.
Helicorder for Plate Boundary Observatory borehole seismometer B207, which is
about 7 miles (12 km) northeast of the 2010 swarm. Seismicity is shown for the
entirety of the swarm so far, from January 17, 2010 through the morning of
January 30, 2010. Click on the image for a larger, more detailed version.
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 to determine what are correct earthquakes from that 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. There are currently seven members of the University of Utah Seismic Stations group who are working 24/7 to analyze the 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.
To learn more about why seismologists need to review earthquakes see our new FrequentlyAsked Question, How are Yellowstone earthquakes analyzed and mapped? .
RSAM plot for PBO borehole seismometer B207 since the beginning of the swarm to the present. Real-time Seismic-Amplitude Measurement (RSAM) was developed by the USGS to summarize seismic activity during heightened volcanic activity. For more information on RSAM see the Alaska Volcano Observatory's RSAM page. Click on the image for a larger version.