After our big quake of 2011, I’m sure you all received a good rubbing from any west coast friends or relations you might have. I think we all saw the famous earthquake “damage” photo that circulated. However, after all the nay-sayers died down, I really started to wonder about the history of earthquakes in Delaware. This is when I decided to do some digging and what I found, well let’s just say, was quite interesting.
Earthquakes in Delaware (whether they occur in Delaware or outside of Delaware and are just felt here) are actually pretty common. In fact, according to the Delaware Geologist Survey (DGS), fifty-eight earthquakes have been documented in Delaware since 1871.[i] Now, that doesn’t compare to California, who in one year received up to 70,000 earthquakes[ii] but for our small state, I think that’s pretty impressive.
According to The Northeast States Emergency Consortium (NESEC), “The Northeast has a long history of earthquakes. Some of the first explorers were startled when they experienced strong shaking and rumbling of the earth beneath their feet. The Pilgrims felt their first earthquake in 1638. A recently released report by one of the Northeast’s foremost seismologists Dr. John Ebel has shed some light on the possible epicenter and magnitude of the 1638 earthquake. He found that the French colonists on the St. Lawrence River and the English along the Massachusetts coast felt this quake with equal intensity. In order for this to happen he believes the most likely epicenter would be central New Hampshire with a magnitude of 6.5 to 7.”[iii]
So it looks like Delaware is officially earthquake country! In fact, in 1997 Delaware was reclassified from being a low seismic risk state to being a medium seismic risk state by the U.S. Geological Survey (USGS) and the Federal Emergency Management Agency (FEMA). [iv]
Now, before you start packing your bags and looking for safer (unmoving) ground, take a look at this map of seismic activity I found.
Delaware does have activity, but it’s not nearly as much as some of our northern neighbors. So, while it is good to be prepared for an earthquake, does it mean we need to panic? I would say no. Delawareans should know the proper procedures to take when (not if) the next earthquake strikes. This will help us and our state and local governments handle the threat in a much more effective manner.
Finally, to put all your worries at ease, I would like to share with you a brief history of Delaware earthquake. This exert was taken directly from the Earthquake Information Bulletin, May – June 1971:
One of the 13 original States, Delaware entered the Union in 1787. But its residents had noted effects from two earthquakes before that time, a strong New York shock a half-century earlier and another in 1755 off the Massachusetts coast. Neither caused damage in Delaware, but the first knocked chimneys over in the New York City area; the second downed walls and chimneys in the Boston vicinity, broke gable ends and vanes on buildings, and opened small ground cracks, an undually severe shock for that area.
The only earthquake to center in Delaware and cause severe property damage occurred on October 9, 1871. At Wilmington, Delaware’s largest city, chimneys toppled, windows broke, and residents were quite bewildered by the unusual event. Lighter damage was sustained in northern Delaware at Newport, New Castle, and Oxford. Earth noises, variously described as “rumbling” and “explosive,” accompanied the shock in several areas.
A tremor in March 1879 on the Delaware River, not far from Dover, was felt “strongly” in that area according to old seismic records. The records, however, do not describe the “strong” effects.
The last shock to center in Delaware and cause minor effects occurred on May 8, 1906, just three weeks after the noted San Francisco earthquake in California. Records state this shock was strong at Seaford, in southwest Delaware, but list no details concerning the event.
Two tremors in recent years, both below intensity V, occurred in Delaware, one on the Lower Delaware in December 1937, and one near Wilmington in January 1944.
Nine earthquakes centered outside Delaware have been felt within the state. These include the two previously described in New York and Massachusetts, four minor New Jersey, and three major earthquakes – two in Canada and one in South Carolina. The South Carolina quake, the strongest in Eastern U.S. history, destroyed much of Charleston in August 1886, and shook up a region from Boston and Milwaukee in the north to Bermuda and Cuba in the south.
The most recent earthquake to be “felt” in Delaware occurred in southern New Jersey in December 1968. Wilmington residents noted slight effects of the Richter magnitude 2.5 tremor, which caused no damage as it rumbled through New Jersey, Pennsylvania, and Delaware.[v]
“I feel the earth move under my feet” (Carole King)