Wednesday, November 12, 2014

MONUMENTAL PLANETARY TREMORS: Scientists - Nevada Earthquake Cluster Is The Biggest In A Decade; Could Be The Precursor To A Larger Earthquake To Come!


November 12, 2014 - NEVADA, UNITED STATES
- Scientists in Reno and across the West are keeping a close eye on an earthquake cluster shaking a remote area where Nevada meets Oregon and California, acknowledging the series of temblors that continued Tuesday could be the precursor of a larger earthquake to come.

There is, of course, no way to know for sure.

"This is kind of the gold medal of swarms over the last decade," said Graham Kent, director of the Nevada Seismological Laboratory.

Already, Kent said, this latest swarm has surpassed a previous Nevada earthquake swarm that shook the Mogul area west of Reno in 2008, another that hit Spanish Springs last year and a third that impacted the Hawthorne area in 2011.

Since mid-July, more than 500 earthquakes of magnitude 2 or greater have hit an area located west of Nevada's Sheldon National Wildlife Refuge about 40 miles northeast of Cedarville, Calif., and 40 miles southeast of Lakeview, Ore. The swarm increased in intensity last week, with the strongest quake of magnitude 4.7 hitting Nov. 5. Quakes have continued this week, with several exceeding magnitude 3.

"It's certainly more vigorous than the Mogul swarm," Kent said, adding that should a quake of magnitude 6 or greater occur, towns like Cedarville and Lakeview could be significantly affected.

Kent and colleagues see some parallels to this cluster and the one that rattled nerves of residents in the Mogul-Somersett area over two months in 2008. That swarm consisted of an "increasingly vigorous" set of quakes, causing moderate local damage, that culminated with a magnitude 5 event.


Geologist Craig dePolo looks over a map in 2008 showing where the spate of earthquakes were clustered in the Mogul area. (Photo: David B. Parker/RGJ )

"The general trend over time is the largest magnitude in each burst is larger than the largest magnitude in the last burst," Kent said. "In the next one do we get a 5-plus? Obviously no one knows that answer."

Some scientists have speculated groundwater is slowly percolating along faults in the area of the latest cluster, making fault movement more likely. Kent isn't convinced groundwater is a major factor.

"I don't know that there is anything special (about groundwater) in that area," Kent said. "It's just another example of these swarms that seem to plague this area."


Dean and Sandy Jung examine one of many cracks that occurred at their Mogul home during an earthquake swarm in 2008. A new swarm of quakes
now occurring on the Oregon line is “more vigorous” than that event, seismologists say. (Photo: RGJ file )

The same remote characteristics that make it difficult for seismologists to install equipment to study the latest cluster also limit the amount of attention it is getting from the public.

Were the area as densely populated as west Reno, the swarm would be getting as much or more attention than the swarm that hit there six years ago, Kent said. It would also be of greater concern, he said.

Kent noted that for the last 60 years or so, Nevada – one of the nation's three most seismically active states – has been relatively quiet when it comes to earthquakes. Other periods farther back in history have produced more quakes, some of them strong, including in the Reno area.

"We are actually in a very quiet period where a few of these swarms get our attention," Kent said. "There has been a lot more activity in the past and we just have to keep that in mind." - RGJ.




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