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Science Forum Index » Geology Forum » Earthquaqe Swarm in Reno, Nevada baffle Experts
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| SBC Yahoo |
 Posted: Thu May 01, 2008 11:40 am |
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Guest
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http://www.latimes.com/news/local/la-na-quakes1-2008may01,0,2696106.story
The 'Mogul sequence' is especially shallow and is growing over time, defying
patterns and predictions.
By Ashley Powers and Thomas H. Maugh II, Los Angeles Times Staff Writers
May 1, 2008
MOGUL, NEV. -- An unusually intense swarm of earthquakes -- more than 1,000
over the last two months -- has struck beneath a small suburb of Reno,
leaving residents shaken and scientists puzzling over the cause.
More than 20 quakes of magnitude 2 or higher have hit on some days, and the
intensity and frequency of the quakes have been increasing rather than
following the normal pattern of tailing off.
Although Nevada is the second-most seismically active state in the
continental United States, researchers say they have never seen anything
quite like the "Mogul earthquake sequence," as they have named it.
"We don't know what is going to happen next," said geologist James Dolan
of USC, who has been watching the unfolding seismic activity. But a swarm
like this "makes you perk up your ears and start considering the possibility
that you might be in a heightened period of hazard."
The swarm of quakes has unnerved the roughly 3,000 residents who live
around Mogul, a sparse community of ranch homes about two miles west of
Reno.
"I lie in bed at night and I can feel" the quakes, said 72-year-old
retired pressman Howard Seeman as he sipped a glass of white wine at
Moxie's, a neighborhood bar close to Mogul. "It's scary, and you never know
what is coming next."
Still, with the biggest quake measuring a modest magnitude 4.7 and no
significant damage or injuries resulting, residents are keeping their sense
of humor about it. Some folks "are joking about moving to California to get
away from the earthquakes," Seeman said.
The Mogul sequence began Feb. 28 with a small tremor about a mile beneath
the town. Over the following weeks, repeated small quakes struck the area.
About every third day or so, there would be a quake with a magnitude
greater than 2 mixed in with the smaller temblors, said Nevada state
geologist Jonathan Price.
A new pattern
The number of daily quakes grew slowly, and then a shift in the pattern
occurred April 15, when magnitude 2 quakes began occurring about three times
a day.
On April 24, the area suffered a magnitude 4.2 quake, and the number of
magnitude 2 quakes, which are slight but noticeable, jumped to 20 a day or
more, Price said. Before April 22, there had been more than 400 quakes. Last
week alone, there were 500.
The biggest series of quakes struck Friday evening -- a magnitude 3.3
temblor, followed 11 seconds later by a magnitude 4.7, the strongest in the
Reno area in more than half a century -- and then a 3.4 three minutes after
that.
Normally, in an earthquake swarm, the main shock hits and then is followed
by a series of ever smaller quakes. But this swarm "has been growing with
time, which is actually quite unusual," said geologist Brian Wernicke of
Caltech. "I can't think of any other example where that has happened."
Earthquake swarms also usually occur much deeper, at least 5 miles below
the surface and often much deeper than that. "It's very, very rare to get
earthquakes of any kind in the upper kilometer," USC's Dolan said.
Jean Frisk, 60, moved to Reno last August from the Bay Area, where she
survived the Loma Prieta quake in 1989. Over a cup of coffee at Moxie's,
where virtually everyone was chattering about the swarm, the retired
hardware store cashier said that she had never considered earthquake
insurance while living in California.
But Friday's 4.7 temblor, following all of the earlier quakes, so unnerved
her that she went out first thing Monday morning and bought a policy.
Seeman said Friday's quake had his ceiling fan swinging so hard that it
was nearly banging the ceiling.
It's the anticipation that is excruciating, he said. "With a hurricane or
a tornado, at least you can see what is coming. But an earthquake sneaks up
on you."
Erwin Renz, 89, said Friday's 4.7 made him decide to stockpile some
earthquake supplies. Renz, who was walking his Labrador retriever Willie
through the quiet streets of Mogul on Tuesday, said he went out and laid in
stocks of canned fruit, vegetables, water and beer, "just in case."
- - - - -<> <> - - - - -
Sounds like the preview to a Volcano errupting. I wonder if gas emissions
have been occuring in the area. SO2 and CO routinely appear from the
grounds in the Mamouth Ski area, about 40 miles East of Reno.
Then there is the famous Long valley Cladera and Monyo Craters in the
genreal area.
http://volcano.und.edu/vwdocs/volc_images/north_america/california/long_valley.html
Reno, here today, gone tomorrow?
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| Jo Schaper |
| Posted: Thu May 01, 2008 10:31 pm |
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Guest
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SBC Yahoo wrote:
Quote: http://www.latimes.com/news/local/la-na-quakes1-2008may01,0,2696106.story
The 'Mogul sequence' is especially shallow and is growing over time, defying
patterns and predictions.
By Ashley Powers and Thomas H. Maugh II, Los Angeles Times Staff Writers
May 1, 2008
MOGUL, NEV. -- An unusually intense swarm of earthquakes -- more than 1,000
over the last two months -- has struck beneath a small suburb of Reno,
leaving residents shaken and scientists puzzling over the cause.
More than 20 quakes of magnitude 2 or higher have hit on some days, and the
intensity and frequency of the quakes have been increasing rather than
following the normal pattern of tailing off.
Although Nevada is the second-most seismically active state in the
continental United States,
No it isn't. Alaska is. It's still on the same continent.
But thanks for posting. NPR Talk of the Nation had a 20 minute segment
on this today-- interview with a high school earth science teacher from
Reno whose class is tracking this, and call-ins from a number of locals.
I found it interesting the degree of damage people were reporting, since
the maximum was apparently the 4.7. That was roughly the same as the
Bellmont, IL aftershock I felt, and it didn't do anything except rattle
stuff around.
Anyone suspect nuclear testing, because of the shallow depth? Just
wondering...I know one can tell the diff between nuclear and eq
signatures, but this sounds slightly suspicious.
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| Charles |
| Posted: Thu May 01, 2008 10:57 pm |
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Guest
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On Thu, 01 May 2008 22:31:11 -0500, Jo Schaper
<jo345sch765aper@s9ocket.net> wrote:
Quote: SBC Yahoo wrote:
http://www.latimes.com/news/local/la-na-quakes1-2008may01,0,2696106.story
The 'Mogul sequence' is especially shallow and is growing over time, defying
patterns and predictions.
By Ashley Powers and Thomas H. Maugh II, Los Angeles Times Staff Writers
May 1, 2008
MOGUL, NEV. -- An unusually intense swarm of earthquakes -- more than 1,000
over the last two months -- has struck beneath a small suburb of Reno,
leaving residents shaken and scientists puzzling over the cause.
More than 20 quakes of magnitude 2 or higher have hit on some days, and the
intensity and frequency of the quakes have been increasing rather than
following the normal pattern of tailing off.
Although Nevada is the second-most seismically active state in the
continental United States,
No it isn't. Alaska is. It's still on the same continent.
But thanks for posting. NPR Talk of the Nation had a 20 minute segment
on this today-- interview with a high school earth science teacher from
Reno whose class is tracking this, and call-ins from a number of locals.
I found it interesting the degree of damage people were reporting, since
the maximum was apparently the 4.7. That was roughly the same as the
Bellmont, IL aftershock I felt, and it didn't do anything except rattle
stuff around.
Anyone suspect nuclear testing, because of the shallow depth? Just
wondering...I know one can tell the diff between nuclear and eq
signatures, but this sounds slightly suspicious.
Location is a bit wrong, I doubt that they would test right under
Reno. |
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