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August 24, 2011

How big was Tuesday's quake?

If you've never experienced an earthquake before - and most people on the East Coast haven't - Tuesday's shaker was HUGE. It shook things that aren't ever supposed to shake, and rattled us in every sense of the word. We will all remember where we were when it struck, and we may never experience anything like it again in our lifetimes, at least not in Maryland.

But earthquakes certainly do occur in the Eastern United States. Small ones are rather common. Damage 1886 Charleston quakeMaryland's most recent one was just last summer. And there are some very big ones in the history books. So how does Tuesday's quake fit into the picture?

Charles F. Richter, of the California Institute of Technology, didn't develop his earthquake magnitude scale until 1935, so any rankings for earthquakes before that are estimates based on anecdotal reports of the shaking, and written damage accounts. (On the scale, each whole number increase reflects a 10-fold increase in measured amplitude, or shaking, and an energy release about 31 times the power of the previous whole number. 

The U.S. Geological Survey says the 5.8 quake near Mineral, Va. on Tuesday was nearly as strong as the estimated magnitude 5.9 shaking in May 1897 centered in Giles County, in southwestern Virginia. The Giles County quake is regarded as the strongest on record for Virginia. That makes Tuesday's quake the strongest Virginia earthquake in 114 years.1886 Charleston quake damage

Much like the Mineral quake, and many Eastern earthquakes, the Giles County quake was felt far from the epicenter  - from Pennsylvania to Georgia, and from the Atlantic to Indiana and Kentucky, according to the USGS. The walls of old brick houses were cracked, bricks broke off chimneys, and clear springs turned muddy. Aftershocks were felt in June, September and October of that year.

But the Mineral quake was a long way from being the strongest to strike the East Coast since we began keeping records. That distinction goes to the Great Earthquake of 1886, the one that nearly leveled Charleston, S.C. (photos) That one is estimated to have been a magnitude 7.3 on the Richter Scale.

The Charleston earthquake was felt strongly in Baltimore, as were the New Madrid, Mo. quakes in 1811-1812. 

Tuesday's earthquake occurred in the Central Virginia Seismic Zone. The strongest quake on record there before this week was an estimated 4.5 shake in 1875. So yesterday's event can be said to be the strongest there in 136 years.


Posted by Frank Roylance at 1:27 PM | | Comments (6)
Categories: Earthquakes


Why was most of the damage in Fell's Point? I noticed a comment on this
that lower Manhattan is in greater danger because it is built on landfill. Is that true of Fell's Point/Canton?

The earthquake itself is a nothing event. The story of the earthquake is a big deal because the East coast media is all over it. That same morning, a stronger earthquake hit Colorado and there's been almost no mention of it. Typical East Coast media hype.

FR REPLIES: First, the Colorado quake was a 5.3 on the Richter scale, significantly smaller than Virginia's 5.8. Second, the Virginia quake affected far more people, from South Carolina to Maine to Michigan, and including the densely packed Washington-Boston urban corridor, which had 50 million people in the 2000 census. The Colorado quake occured in Trinidad, CO, 180 miles from Denver, the nearest big city. And third, remember that the "East Coast media" are mostly local media, and we cover what happens in our communities. An earthquake happened, the first for most of our readers. We covered it.

Hello Frank,

After informally asking around, I've found that many folks had the sense that the earthquake moved from the east towards the west when in fact the tremor was coming at us from the southwest. Do you know if this was a common perception, and if so, why so many people, including me, initially thought that the quake took place somewhere to our east. Thanks in advance for any input you may have.

FR REPLIES: I've never seen or heard anything that would suggest that people can judge the origin of a quake by the movement they feel.


It is a big story because most people in the Mid Atlantic and other environs up and down the east coast have not even experienced an Earthquake.

Now for a place like Southern Calif yep it would be ho hum. I am from there and experienced many a earthquake in my time there so I know this well.

But I can tell you walking outside my house afterwards the excitement in the street amongst my neighbors was VERY real. It was even to use a corny term "Electric". So I get the news media being swept up in this as well.

BTW the worst thing anyone can do is run outside in a quake. Falling bricks from the facings of the buildings amongst other hazards will hurt/kill you much more than any unlikely house collapse. Of course me being an expert I waited for the rocking to stop before I even left my chair. :-)

Fran In Baltimore


"Typical East Coast media hype." ??

You mean like the "typical East Coast media hype" covering the Loma Prieta earthquake in California in 1989?

You mean like the "typical East Coast media hype" covering New Orleans when Hurricane Katrina struck in 2005?

You mean like the "typical East Coast media hype" covering the flooding in the Mississippi River Valley this past spring?

You mean like the "typical East Coast media hype" covering the flooding in the Missouri/Mississippi River Valleys in 1993?

You mean like the "typical East Coast media hype" covering the flooding near the Missouri flooding this past spring?

You mean like the "typical East Coast media hype" covering the tornadoes in the Great Plains and MidWest each and every year?

You mean like the "typical East Coast media hype" covering the flooding in Nashville, Tennessee in 2010?

Notice that ALL the above are hundreds, if not thousands, of miles from the East Coast?

At least you have some interesting information here. Most of the "stories" are about how many "tweets" were sent after the earthquake or how people "evacuated" their offices. OMG a crack in a church!! Dynamite reporting on those...

The story is that there was an decent size earthquake in an area that isn't typically seismically active. That's it.

There's been some real stretching by reporters on some of these earthquake "stories" trying to make something out of nothing. Number of tweets = not news. Next thing you know, the story will be about all the BS stories written about the earthquake.

Better than the typical stories about people who were murdered overnight, I guess. But just as lazy.

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About Frank Roylance
This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff

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