Earthquake History, East Coast USA, Continental Shelf

August 23, 2011, by Ken Jorgustin

east-coast-earthquake-history-map

Map of US East Coast Earthquake History

(updated to include the August 23, 2011 earthquake location)

 

Latest major activity (on land):
UPDATE, AUGUST 23, STRONG EARTHQUAKE ROCKS EAST COAST USA, VIRGINIA

 

…original post
An unusual magnitude 3.9 earthquake rumbled beneath the Atlantic Ocean seafloor off the East Coast of the United States on November 30, 2010. It was unusual in the fact that it was located offshore of the east coast United States, where there is just a spotted history of earthquake activity.

atlantic-ocean-east-coast-usa-earthquake-location-30-nov-2010

The earthquake occurred at a depth of 6.6 km, only about 100 miles off the coast of New Jersey and Long Island at the mid-Atlantic continental shelf region.

The eyebrow raising fact of this earthquake was its location. That is, right on the edge of the continental shelf where the seafloor drops from a depth of 500 feet all the way down a steep cliff to about 7,000 feet before gradually dropping further to depths as deep as 20,000 feet.

The location of the earthquake, although 4 miles below the surface (about 21,000 feet), is centered literally right on the top edge of the 7,000 foot cliff.

It is unimaginable to think about the consequences if part of the 7,000 foot cliff were to crack and fall away to the seafloor. Can you say, ‘Tsunami’?

There is no indication that this is a current possibility, simply an observation based on the location coupled with the fact that we don’t often see earthquakes in this general location.


Earthquake history of the mid-Atlantic continental shelf

earthquake-history-mid-atlantic-continental-shelf

 

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