TO SHAKE & QUAKE AGAIN?

On the afternoon of August 10, 1884, a relatively minor earthquake hit New York City. Estimated to have been 4.9 to 5.5 in magnitude, with its epicenter off the coast of Coney Island or Far Rockaway, the quake lasted for about 10 seconds but caused little damage. Nonetheless, it was felt as far south as Baltimore and north as Maine; an area of over 70,000 square miles.

Newspapers of the day reported:

The telegraph manager at Coney Island promptly asked for particulars of the ‘explosion,’ supposing that some oil refinery, powder mill or dynamite factory had blown up. A few minutes later, however, the fact became known there that the whole island had been thoroughly shaken by the vibrations. As a rule people remained in front of their houses for many minutes, apparently trying to get at some solution of the fears and watching the faces and way of others.  Women and children as they regained some degree of confidence returned to their houses.  Men assembled in groups in the streets discussing the occurrence which had so startled them.  The faces of men and women, however, wore a troubled expression and bespoke a dread that perhaps the danger was not yet over.  The effect of the jar was much more perceptible in houses of light structure, in many instances it being reported that a clearly defined movement was felt, and the dishes in pantries were shaken from the shelves.  In Central Park the shock was more severe, it is said, than in the surrounding region.  There were large crowds in the mall, who were at once thrown into a state of violent excitement by the shaking and strong rumbling in the ground, which was distinctly heard.  The animals in the menagerie were evidently frightened by the shock, and many of them were seen to tremble as if in fear, while they remained perfectly still for some time after it occurred.  General Disasters (transcription)

(more articles here)

This wasn’t the first earthquake to hit this region where seismic disturbances result in a moment of alarm, a modicum of damage, and a quick dismissal. On December 18, 1737 an earthquake of similar size hit the city, toppling chimneys and cracking windows; and throughout the next two centuries, down to the present day, various other small size earthquakes have struck in and around the metropolitan area.

However, the 1884 quake is, to date, considered to be the largest and best documented in New York City history. As never before, scientists began exploring the geology of this region: its insidious fault lines and deceptive seismography. NYC Seismicity

While places like California are certainly no strangers to earthquakes and the culminating “Big One” has loomed large in their future for decades, our own corner of the world isn’t immune from a similar fate.

Much of Manhattan sits on a deep layer of soft, post-Ice Age sediment over extremely hard rock, a juxtaposition of geological extremes that bodes ominously. A 6.0 quake could shake the city’s buildings with nearly the intensity of the 6.8 quake in Kobe. Inexplicably, the city dragged its feet about adding earthquake-mitigating requirements to its building codes until the mid-1990s. The generally well-designed towers in the Manhattan’s skyline most likely would survive a 6.0, but the unreinforced masonry townhouses where most residents live might not fare so well. A 1989 study estimated that a quake would cause more than 130 simultaneous blazes, which could put the fire department under severe strain  TLC

In short, a major earthquake would be quite a shitty experience for NYC. Nevertheless, as with all impending natural disasters, the Big One could strike now or 10,000 years from now.  Personally, I won’t be packing my bags for a hasty departure anytime soon. When I think of the various disasters that I’ve lived through here, what’s so terrible about a devastating earthquake or two.

(For some highly technical stuff on NYC earthquake forecasts, go here)

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