A swarm of earthquakes in a sparsely populated area of far northwest Nevada that began on July 12, 2014, has increased in intensity over the past several days. This activity is located about 40 miles southeast of Lakeview, Ore., and 40 miles northeast of Cedarville, Calif. During the past three months the Nevada Seismological Laboratory, in collaboration with the U.S. Geological Survey and seismic networks in Washington and Oregon, has recorded 42 earthquakes larger than magnitude 3, and about 550 earthquakes larger than Magnitude 2. Three Magnitude 4+ events have occurred since Oct. 30, with the largest event of the sequence, Magnitude 4.6, at 11:23 p.m., Nov. 4, 2014 (PST).
This 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 analog is the 2008 “Mogul-Somersett” swarm in west Reno. This swarm also consisted of an increasingly vigorous series of earthquakes over a two-month period, leading to a Magnitude 5 event. The Mogul sequence also caused moderate local damage.
Following any sequence of earthquakes similar to what is occurring in northwest Nevada, there is a small increase in the probability of a 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 we encourage citizens 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.