Skip to comments.East vs. West Earthquakes: Way Different Creatures (East coast quakes are rare, affect larger area)
Posted on 08/24/2011 12:04:24 PM PDT by SeekAndFind
The East Coast doesn't get earthquakes often but when they do strike, there's a whole lot more shaking going on.
The ground in the East is older, colder and more intact than the West Coast or the famous Pacific Ring of Fire. So East Coast quakes rattle an area up to 10 times larger than a similar-sized West Coast temblor.
"They tend to be more bang for the buck as far as shaking goes," said Virginia Tech geology professor James Spotila.
Tuesday's 5.8-magnitude quake was centered in Virginia and was felt up and down the Eastern seaboard for more than 1,000 miles. There hasn't been a quake that large on the East Coast since 1944 in New York.
While this was a rarity for the East, a 5.8 quake isn't unusual for California, Oregon, Washington and Alaska, where one occurs about once a year. Those states have had 103 quakes 5.8 or bigger since 1900, compared to now two in the East.
The tiny island of Trinidad is more quake-prone than the East Coast, said U.S. Geological Survey seismologist Paul Earle.
"In all the years I was at FEMA, there didn't seem to be a concern for earthquakes on the East Coast," former Federal Emergency Management Agency chief James Lee Witt said.
Because of geology, earthquakes on the coasts have different triggers and act differently in some ways. And they definitely are felt differently.
One glaring East versus West disparity: When a quake happens in California, geologists usually know what fault ruptured. Tuesday's quake happened on an unknown fault, and it is likely to remain a mystery.
Because the quake didn't break the surface "we may never actually map this fault from this earthquake," Earle said.
The only thing that will help scientists figure out where the break truly occurred are the aftershocks which could help highlight or outline the fault line, said Cornell University seismologist Rowena Lohman.
Most of the times, quakes occur when Earth's floating giant plates shift, rub against or slip past each other. That's what happens along California's San Andreas fault when quakes happen there.
Tuesday's thrust earthquake was far from the edge of a platethe nearest are thousands of miles away in the mid-Atlantic or California, said seismologist David Applegate, associate director of natural hazards for the USGS in Reston, Va.
The stresses that cause these kinds of quakes come from far away and mount ever so slowly over time, even building up from the retreat of glaciers at the end of the Ice Age, he said.
Another East versus West contrast: The ground is different in the East in a way that makes the shaking travel much further, allowing people to feel the quake several states and hundreds of miles away.
The rocks in the Earth's crust in the East are colder, older and harder, which means seismic waves travel more efficiently and over greater distances. Rocks on the West Coast are relatively young and broken up by faults.
"An intact bell rings more loudly than a cracked bell and that's essentially what the crust is on the East Coast," USGS seismologist Lucy Jones told a news conference in Pasadena, Calif.
In the East, hurricanes are the worry far more than quakes. Former FEMA chief Witt said people on the West Coast know what to do in an earthquake: drop to the floor, cover their heads and hold on to something sturdy until the shaking stops.
That's what USGS's Applegate did in Virginia.
"It's seared in our heads," said USGS seismologist Susan Hough in Pasadena. "People back East don't get that kind of preparedness message.
I don't know what the West Coast does.
7.0 Magnitude in Peru today
7.0 Magnitude in Peru today
5.8 quake isn’t unusual for California, Oregon, Washington and Alaska, where one occurs about once a year. Those states have had 103 quakes 5.8 or bigger since 1900
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I think they better check their math. Looks like over 800 just for Alaska.
In California we stir our coffee with 5.8 quakes.
On the East Coast it’s dress over the head time.
One other contrast between east & west coasts - the amount of quake caused property damage and dead bodies.
I don't know what the West Coast does.
Yep. On the west coast, earthquakes kill people.
“East vs. West Earthquakes: Way Different Creatures”
And earthquakes out here in flyover, driven largely by the huge New Madrid fault, matter not at all.
Just like the weather. This summer’s heat wave didn’t start making real news, until it reached the important folks up east.
Wait! Wait! Wait! Isn’t the New Yawkers who are always telling us how tough and brave they are? But isn’t it
the New Yawkers who stayed where they are and wasn’t it
others, including people from New York, who took up Conestoga Wagons, barrels of flour and flint lock muskets and went west? And then I listened to New Yawkers talking
on the news about how the earthquake scared them. It’s time we expose this brave New Yorkers baloney for exactly what it is. Baloney.
Flooding in Nashville, yawn.
Coloradans trapped by a blizzard. no biggie.
Fires in Texas. what?
Drought all over the middle US. “did you say something?”
Tornados in Missouri. What 2 or 3 days worth of their attention.
But when bad weather affects the eastern power corridor, it’s armageddon.
Here in the northeast, we likewise laugh at the panic that is caused by an inch of snow in Texas, Georgia, or Southern California.
So I guess we’re even. If haven’t had an experience with an unusual act of nature, no matter how mild it is, it’s a little disturbing.
I wonder what acts of nature they have to worry about in Hawaii...
That’s a good point. I rememeber laughing when the local radio station(in Va) would somehow play psa’s telling Californians to be really careful when they drive in the rain. Yesterday was the first time for me as far as earthquakes go, and I take it that it was pretty mild as far as severity of damage, so fair enough.
As a result of the most recent quakes, the siesmologists hae identified a new fault. It runs from Ithaca to Manhattan and up to Boston, running not far from Martha’s Vinyard. It als goes through Philadelphia and Baltimore into Washington DC, then through Virginia all the way to New Orleans. It is the Bush Fault.
I felt it in LA. (Lower Alabama)
That joke about Bush’s Fault and the earthquake is old news by now.
In particular, I recall one centered in southern Illinois on November 9, 1968, a Saturday.
It was felt in at lest parts of 23 states and Canada. But it was revised down to 5.4 on the Richter scale. As in the Virginia quake yesterday, there were no reported deaths, but some property damage near the epicenter. The most serious injury reported was a concussion suffered by a child hit in the head by falling debris. It is the largest quake ever recorded centered in the state of Illinois.
I always thought it was odd that there was a very small fault line at Charleston, SC. There was a very devasting earthquake there in 1886, estimated at 7.6