Two 4.7 magnitude earthquakes and more than 50 3.0 or greater magnitude earthquakes mark an uptick in seismic activity one week after a 4.6 magnitude earthquake struck far northwest Nevada on Nov. 4, 2014. The activity in the past week is more than in previous months combined.
This ongoing swarm is located about 40 miles southeast of Lakeview, Ore., and 40 miles northeast of Cedarville, Calif. During the past week, the University of Nevada, Reno’s Nevada Seismological Laboratory, in collaboration with the U.S. Geological Survey and seismic network operators in Washington and Oregon, has recorded six earthquakes larger than magnitude 4.
The largest two events (M4.7) occurred just after midnight Nov. 6 and Nov. 7. A magnitude 4.1 earthquake struck the area this morning, Nov. 12, at 6:42 a.m. This recent activity marks an increase in both magnitude and number of events for this swarm that began five months ago. In total, there have been 101 earthquakes larger than 3.0, the largest being magnitude 4.7, and eight earthquakes have been larger than magnitude 4.0.
“The Nevada Seismological Laboratory is in contact with local residents in hopes of deploying instruments near the swarm in the upcoming week,” Graham Kent, director of the lab, said. “Residents of northwest Nevada have expressed an eagerness to help as they are feeling the daily barrage of M3 and M4 earthquakes.”
The activity resembles the 1968 Adel, Ore., swarm, which also lasted several months and included three events of approximately magnitude 5. The Adel swarm caused moderate damage. Another comparison is the 2008 Mogul-Somersett swarm in northwest Reno that involved an increasingly vigorous series of earthquakes during a two-month period leading to a magnitude 5 event. The Mogul sequence also caused moderate local damage.
For reference, the Mogul sequence included three earthquakes larger than magnitude 4, just half of the magnitude 4s in the past week alone in the current Sheldon National Antelope Refuge swarm. The current swarm is more reminiscent of a series of shallow earthquakes outside of Hawthorne, Nev., in 2011, where a similar number of magnitude 4 or greater earthquakes struck over a four-month-long period.
Following any sequence of earthquakes similar to what is occurring in northwest Nevada, there is a small increase in the probability of a significantly larger event. Whether a larger event will occur in the northwest Nevada swarm cannot be predicted or forecast. However, large earthquakes can happen anywhere in Nevada, and citizens are encouraged to take steps to prepare for the potential for strong ground shaking.
For earthquake preparedness information, visit http://www.seismo.unr.edu or http://earthquake.usgs.gov/learn/preparedness.php.
The Nevada Seismological Laboratory at the University of Nevada, Reno, the Pacific Northwest Seismic Network at the University of Washington, the Oregon Department of Geology and Mineral Industries and the U.S. Geological Survey are closely monitoring this earthquake activity.
Real-time earthquake information on this sequence is available at http://www.seismo.unr.edu, and http://earthquake.usgs.gov/earthquakes/map/.
For more information on Nevada earthquake activity, contact the Nevada Seismological Laboratory, 775-784-4975.
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