Skip to comments.EARTHQUAKES IN THE CENTRAL VIRGINIA SEISMIC ZONE
Posted on 08/23/2011 3:00:46 PM PDT by COBOL2Java
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).
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.
Earthquake Information for Virginia
Gaia must be very angry at General Motors for not selling enough full-efficient cars. We must make a sacrifice to her. Can anyone suggest someone to through into the pit?
I am just outside of DC, and our office building shook incredibly hard. Some of the damage on the news is right near our building. When the shaking started it was more interesting than scary, but man, once it ramped up after a few seconds it was LOUD and I thought our building was going to collapse.
Inside our office lots of pictures, monitors, books, etc, fell all over the place. Many of my friends and family were in stores and their workplaces and dealt with minor damage as well.
I am still in shock that we actually felt an earthquake that strong here on the East Coast. My understanding is this 5.8 was relatively shallow and created a situation where it felt much more powerful than a 5.8 on the West Coast.
One of my coworkers in NY has been unable to use his cell phone all day.
Not because a cell tower fell, but from all the earthquake newbies calling in a panic!
I must confess, I contributed to the jammed phone lines. I am a true earthquake newbie ;)
I'll tell you though, this thing shook really hard here just outside of DC. It was very loud too. We started coming out of our offices into the lobby and it was almost a novelty at first, but it really ramped up for about 10 seconds and got quite scary. I remember thinking, "oh crap, this building couldn't possibly survive this". I suppose we did exactly what your not supposed to - we took off down the stairs and out of the building.
I will never forget the feeling of that earthquake. Something I see on TV quite often, but never expected to actually experience it myself.
I am guessing Bush’s Fault?!
Your very near where I am. I'm working right now in Vienna, VA in a 10 story building. At first I thought the shaking was some sort of building construction, but it started getting louder and more violent and I realized this was something seriously out of the ordinary. We started pouring out of our individual offices into the lobby, and for about 10 - 15 seconds the building shook extremely hard. I know I wasn't the only one that thought the building was going to collapse. Most of us ran down the stairs, and while I realize now it was the wrong thing to do it seemed like everyone was doing the same.
I did not feel an aftershock, but there was a fair bit of damage around us. Watching the news you've probably seen the footage of the townhouses (doctors offices, nail salon, etc) that partially collapsed. That is right near where I was. In fact we walked over and took pictures.
We were all looking at our own building suspiciously now. I assume they will check for structural damage tomorrow.
I am glad you came through it okay. Sounds like other than some minor damage and a rude interruption, you didn't suffer any serious damage. So far, that has also been the case with all of my co-workers, friends and family.
Well who else? The NY Times/CBS just did a snap poll and the results clearly indicate that a majority of Americans believe Bush is responsible for the earthquake ;)
I know it wasn’t a huge quake, but I am really surprised there hasn’t been more damage. I, too, was a little bit concerned about my building. But mostly, the little kid in just kept saying “this is so cool.” What was funny was that right after the quake, people evacuated the building, and were standing right next to the building. I took one look up at all the windows and brick, and decided I liked it better inside.
Yeah, I felt the same way where I was in Vienna. Thing is, right near our building there was a fair amount of damage to that townhouse business complex. Also, calling friends and family that were right near the same area and they reported quite a lot of broken pictures, fallen shelves, knocked over monitors, etc.
What was really odd was I drove home, which is down near Centreville, expecting to see a fair bit of damage at my house and it was as if nothing happened at all. Not even one book, vase, or anything else out of place. I find it really weird because, at least in theory, the Centreville area was closer to the epicenter of the quake. For whatever reason the Vienna (and many other specific areas as I understand it) really got hit hard.
After careful examination and triangulation the Obama Administration just released information the quake originated in the heretofore unreported “Bush’s Fault” zone.
On the plus side all D.C. government workers fled their posts so America was saved for another day !
Its reported the President made an emergency cell call to D.C. to see if his favorite pizza parlor survived, and then ordered a “Chicago-style double-cheese, extra sausage” take out to be picked up by Marine One.
In NYC Mayor Bloomberg and Sen. Schumer jointly declared the quake was, “the result a nefarious NRA gun freedom plot”.
And on the Left Coast Congresssomething Maxine Waters declared the quake was a “racist TEA Party terrorist plot”.
IOW, pretty much another “government as usual” in our fair nation. >PS
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