The New Madrid, Missouri Earthquakes of 1811–1812

[johnwalker]

The "Hard Shock:" The New Madrid Earthquakes.

Earthquakes don’t just happen around “ring of fire” edges of tectonic plates, but also in the middle of continents. They’re rarer, but can be devastating over a large area. Between December 16, 1811 and February 7, 1812, a series of four earthquakes, all with Richter magnitudes in excess of 7, shook the vicinity of New Madrid in the U.S. Louisiana Territory (present day state of Missouri). The earthquakes caused enormous damage to the sparsely populated region, briefly reversed the flow of the Mississippi river, and was felt from the Gulf coast to Canada and on the U.S. east coast.

It is difficult to imagine the damage a similar event would cause today, when most of the construction in the region was not built to the seismic standards enforced on the U.S. west coast.

[Spearfoot]

This is why we carry earthquake insurance on our home; we’re only ~250 miles from the epicenter,

[CTLaw]

@johnwalker

It is difficult to imagine the damage a similar event would cause today, when most of the construction in the region was not built to the seismic standards enforced on the U.S. west coast.

Even a mild earthquake would take out most of the brick buildings in the eastern half of the US. The mortar has decayed and the pressure wave would be like throwing a deck of cards into the air with nothing to hold the bricks together.

Furthermore, many more modern concrete and steel buildings have essentially zero shear protection. They would just rack over as parallelogram mechanisms.

When I first returned east after many years out west, I had a near panic attack when parking in a parking garage that had 10 to 20 foot tall columns and no shear walls.