Magnitude 5.8 - VIRGINIA

Frynge wrote: »

was it a different quake or an after shock of the virginina one.

now revised to 5.9

no reports of damage so far.

snubbleste wrote: »

Has FoxNews outlined which terrorist organisation is responsible? :cool:

CHUCK BANKS on August 23, 2011, 7:07 PM
I work in an 8-story building 45 miles from the epicenter of the VA quake. I was standing next to my desk talking to two guys. It started quite gentle for about 10 seconds. We looked around thinking someone was running past the desk. Suddenly, it got violent, shaking so hard that items on my desk bounced around, and the lights and cubicle walls swayed. The building made terrible cracking and poping sounds. One guy yelled “Under the desks!”, and we all followed within a second. The hard shaking lasted about 10-15 seconds, then it gradually eased off for maybe another 10-15 seconds. Everything was swaying so much that it’s hard to say exactly when the quake ended. Everything in the building seemed perfectly normal when it was over. However, all 7,000 of us decided that evacuation was a good idea after the sounds we heard and the possibility of aftershocks. Security inspected the parking garage, and we were released for the day. We all got out of the parking garage ASAP and went home.

Cell phone lines were jammed for the next hour, but texting worked fine. That’s something everyone should remember in major events. A text only needs a fraction of a second of contact to get through, and your phone will try until it succeeds.

There is minor, but widespread damage. The National Cathedral in DC had three of the four pinacles at the top of the spires fall off. There are pieces of them all over the roof and ground. They are stone, and several feet high.

I just got a call that we are to return to work tomorrow, so I guess the building inspection was okay. I lived in CA for four years, and this was much stronger than anything I felt there.

Solair wrote: »

Could that be because most West Coast structures are relatively earthquake proof?
East Coast buildings are far more like ours, they'd make a hell of a noise and probably crack of even slightly shaken. The pavements / sidewalks and roads would also probably transmit shockwaves too. West Coast pavements have to cope with regular tremors.

I suspect the phone networks just overloaded as everyone suddenly rang everyone else. Cell sites can only host so many calls simultaneously.
It didn't seem to be physical damage as it came back online very quickly afterwards.
We've all experienced this on New Years eve.

EARTHQUAKES IN THE CENTRAL VIRGINIA SEISMIC ZONE
Since at least 1774, people in central Virginia have felt small earthquakes and suffered damage from infrequent larger ones. The largest damaging earthquake (magnitude 4.8) in the seismic zone occurred in 1875. Smaller earthquakes that cause little or no damage are felt each year or two.

Earthquakes in the central and eastern U.S., although less frequent than in the western U.S., are typically felt over a much broader region. 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. A magnitude 4.0 eastern U.S. earthquake typically can be felt at many places as far as 100 km (60 mi) from where it occurred, and it infrequently causes damage near its source. A magnitude 5.5 eastern U.S. earthquake usually can be felt as far as 500 km (300 mi) from where it occurred, and sometimes causes damage as far away as 40 km (25 mi).

FAULTS
Earthquakes everywhere occur on faults within bedrock, usually miles deep. Most bedrock beneath central Virginia was assembled as continents collided to form a supercontinent about 500-300 million years ago, raising the Appalachian Mountains. Most of the rest of the bedrock formed when the supercontinent rifted apart about 200 million years ago to form what are now the northeastern U.S., the Atlantic Ocean, and Europe.

At well-studied plate boundaries like the San Andreas fault system in California, often scientists can determine the name of the specific fault that is responsible for an earthquake. In contrast, east of the Rocky Mountains this is rarely the case. The Central Virginia seismic zone is far from the nearest plate boundaries, which are in the center of the Atlantic Ocean and in the Caribbean Sea. The seismic zone is laced with known faults but numerous smaller or deeply buried faults remain undetected. Even the known faults are poorly located at earthquake depths. Accordingly, few, if any, earthquakes in the seismic zone can be linked to named faults. It is difficult to determine if a known fault is still active and could slip and cause an earthquake. As in most other areas east of the Rockies, the best guide to earthquake hazards in the seismic zone is the earthquakes themselves.

Source: NEIC/USGS


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