Tuesday, August 23, 2011
Eastern Earthquake Provides Useful Warning
It’s great to see the widespread coverage of the eastern earthquake, despite its modest strength (although I’m not sure some of the underwhelming video coverage was worthwhile).
The 5.8-magnitude quake, centered in Virginia 83 miles southwest of Washington, D.C., is a reminder of the importance of factoring in shaking in the design of buildings and important installations like nuclear power plants.
USGS A 6.8-magnitude earthquake in 1895, centered in Charleston, Mo., caused widespread damage and was felt from Louisiana to western New York
While rare, eastern earthquakes can be dangerous, most notably those triggered in the New Madrid seismic zone along the Mississippi River valley.
One issue is that the geology of the east is more favorable to transmitting earthquake energy long distances, as described this way by the United States Geological Survey in context provided for the Virginia quake:
East of the Rockies, an earthquake can be felt over an area as much as ten times larger than a similar magnitude earthquake on the west coast.
This year is the bicentennial of the great New Madrid earthquakes of 1811-12, an anniversary marked by federal disaster agencies in May with an exercise responding to a simulated major quake in the region.
Although some earth scientists in the region, notably Seth Stein of Northwestern University, say the threat of a catastrophic repeat is overblown, that’s no reason not to take shaking into consideration in designing structures or securing items in a house or business to limit losses if the worst happens.
Earthquake disrupts East Coast cell phone service - Aug. 23, 2011
NEW YORK (CNNMoney) -- Cell service along the East Coast was spotty for about a half hour following a Virginia-based earthquake that was felt as far away as New England.
There were no reports of downed cell towers or wires, but mobile providers said the fact that millions of people tried to make cell phone calls at the same time overwhelmed cellular relay stations.
Verizon Wireless reported network congestion for some customers in the Eastern U.S. for about 20 minutes following the earthquake, which hit just before 2 p.m. ET. The quake measured at 5.9 on the Richter scale.
"We are seeing no reports of damage to our wireless network," said Verizon (VZ, Fortune 500) spokesman Jeff Nelson. "Everything returned to normal quickly once the tremors ended. We'll continue to monitor the network."
Nelson said the mobile company's infrastructure was built to withstand earthquakes of such a magnitude. Verizon's super switching centers in Florida, for instance, are designed to withstand a Category 5 hurricane.
AT&T (T, Fortune 500) spokesman Mark Siegel also said that there was no infrastructure damage, but the network continues to see "heavy call volumes." He said customers that could not connect might try to communicate by text message, which requires far less bandwidth than phone calls.
Sprint (S, Fortune 500) told customers via Twitter that the provider is experiencing intermittent delays connecting phone calls following the earth quake, citing a "temporary mass calling event."
A T-Mobile spokesman also confirmed that the network was experiencing higher call volumes in all earthquake-affected areas. The company is advising customers that cannot place calls to communicate by e-mail or text messages until call volumes return to normal.
Cell service disruptions occur during periods of heavy call volumes, because of a bottle-necking factor: Like a highway that gets congested during rush hour, cellular infrastructure is not designed to handle the amount of calling traffic that occurs during emergency situations.
"We don't engineer pipes to handle every call at the same time," said Akshay Sharma, wireless infrastructure consultant at Gartner. "Even though we have redundancy built in, guess what, most of that feeds into same pipes."
Calls are typically routed from relay station to relay station in the shortest distance between the two points of a call. But if one switching station gets overwhelmed, calls then need to be relayed around that station, and delays occur.
Sometimes, congested infrastructure simply results in calls that cannot go through.
First Published: August 23, 2011: 3:08 PM ET
5.9 magnitude quake rattles east coast, causing evacuations in DC | The Raw Story
5.9 magnitude quake rattles east coast, causing evacuations in DC
Breaking news... Developing...
An earthquake measuring 5.9 on the Richter scale struck the state of Virginia not far from Washington, D.C., rattling buildings up and down the eastern seaboard, with reports indicating tremors as far away as Toronto, Chicago, Kentucky and even Daytona Beach, Florida.
The quake will be recorded as the largest on record to hit Washington, D.C. The last major quake the nation's capital experience was in July 2010, when a magnitude 3.6 quake struck. Prior to that, no quakes had been recorded in the region for over 35 years.
The White House and Pentagon were both briefly evacuated, along with many office buildings all over the eastern seaboard. Cell phone service was also disrupted in some areas, especially in Washington, D.C., due to excess capacity.
No injuries or severe property damage has been reported.
Tags: Magnitude 5.9 - VIRGINIA
- This event has been reviewed by a seismologist.
Magnitude 5.9 Date-Time
- Tuesday, August 23, 2011 at 17:51:03 UTC
- Tuesday, August 23, 2011 at 01:51:03 PM at epicenter
Location 37.975°N, 77.969°W Depth 1 km (~0.6 mile) (poorly constrained) Region VIRGINIA Distances 45 km (27 miles) E of Charlottesville, Virginia
55 km (34 miles) SW of Fredericksburg, Virginia
64 km (39 miles) NW of RICHMOND, Virginia
82 km (50 miles) NNE of Farmville, VirginiaLocation Uncertainty horizontal +/- 10.9 km (6.8 miles); depth +/- 7.4 km (4.6 miles) Parameters NST=390, Nph=390, Dmin=57.9 km, Rmss=1.17 sec, Gp= 47°,
M-type=regional moment magnitude (Mw), Version=6Source
- Magnitude: USGS NEIC (WDCS-D)
Location: USGS NEIC (WDCS-D)Event ID usc0005ild
5.8 Earthquake in Virginia Felt in Washington, New York City, North Carolina - ABC News
WASHINGTON August 23, 2011 (AP)
5.8 earthquake in Virginia felt in Washington, New York City, North Carolina
Largest Colorado quake since 1973 shakes homes
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August 23, 2011 (TRINIDAD, Colo.) -- The largest earthquake to strike Colorado in almost 40 years has shaken hundreds of people near the New Mexico border and caused minor damage to a few homes.
The magnitude 5.3 earthquake was recorded at about 11:46 p.m. MDT Monday about nine miles southwest of Trinidad, Colo., and about 180 miles south of Denver, according to the National Earthquake Information Center in Golden, Colo. The quake followed two smaller ones that hit the area earlier in the day.
The quake is the largest in Colorado since a magnitude 5.7 was recorded in 1973, U.S. Geological Service geophysicist Amy Vaughn said. That one was centered in the northwestern part of the state -- about 50 miles north of Grand Junction, she said.
A few homes have been damaged and there were rockslides on Colorado Highway 12 and Interstate 25, but both highways remained open, a Las Animas County Sheriff's Office dispatcher said Tuesday.
The dispatcher, who would only give her first name as Kristina, said she was working when the biggest earthquake hit near midnight.
"Everything was shaking, but we had no power loss," she said.
She said authorities were still trying to assess the damage.
"I thought maybe a car had hit my house," 70-year-old Trinidad resident Nadine Baca said. "Then I called to my son and he said it was the third (quake) today."
Another USGS geophysicist, Shengzao Chen, said the information center had received calls from more than 70 people in Trinidad and several dozen people in New Mexico who felt the shaking. More than 30 people in Colorado Springs, about 130 miles north of Trinidad, also reported feeling the quake, he said.
A magnitude 4.6 quake was felt in the same area at 5:30 p.m. on Monday, and a magnitude 2.9 quake was recorded just before 8 a.m. Two aftershocks -- one recorded at 3.5 and another at 3.8 -- followed early Tuesday, more than an hour after the 5.3 quake.
The last time the area received such a series of earthquakes was in August and September 2001, when about a dozen smaller-sized temblors were recorded, Chen said.
"The area seems to be active again," he said.
(Copyright ©2011 by The Associated Press. All Rights Reserved.)ABC7 Poll
Tags:national/world
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