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. Maryland'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.
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.