Historic Pelham: Earthquake! Is Pelham on Shaky Ground?

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Early yesterday morning, a 6.1 magnitude earthquake damaged buildings and knocked out power to thousands in northern California. Dozens reportedly were injured, some critically.

Earthquakes don't happen in Pelham, do they?

Well, most recently . . . . . . . . Shortly before 2:00 p.m. on August 23, 2011, many in Pelham and surrounding areas could not believe their senses. Dishes seemed to rattle. Tables and chairs seemed to vibrate. Some thought they perceived a rumble. It was not their imaginations. The earth shook that day.

The earthquake felt that day in Pelham (and in more than a dozen eastern states and Canada) originated 4 miles beneath ground surface in Louisa County, Virginia, nearly 350 miles away. It registered a magnitude of 5.8 and a maximum perceived intensity of VII on the Modified Mercalli Intensity scale (very strong).

Could a damaging earthquake occur in Pelham? Is Pelham on shaky ground? The answer to both questions may surprise you: "yes." In fact, history reveals that Pelham already has suffered damaging earthquakes and likely will experience more.

Major Temblors

The earliest major earthquake in the Pelham region in historical times occurred on December 18, 1737. Scientists estimate that like the recent quake centered in Louisa County, Virginia, the 1737 New York quake reached a perceived intensity of VII on the Modified Mercalli Intensity scale and registered a magnitude between 5.0 and 5.5. It toppled chimneys and rang bells in the New York City region and reportedly was felt as far away as Boston, Philadelphia and Delaware.

There is no record of damage in Pelham during the 1737 earthquake. That, however, is no surprise. The region known as the Manor of Pelham at the time was virtually uninhabited. There were only a few households in the area consisting mostly of members of the Pell, Rodman, Rylander and Contine families.

By the 19th century, however, the population of Pelham had grown. On a sultry summer morning, July 11, 1872, just as the sun began to rise, the earth quaked and Pelham shook again. At about 5:30 a.m., according to witnesses, an earthquake seemed to begin to the south and roll to the north. According to the New York Times:

"Houses were shaken to their foundations, and crockery and glassware in the closets were considerably disturbed by the shock. Timid ladies became greatly alarmed, fearing results of a more serious character. In the villages of East Chester, Mt. Vernon, Pelhamville, New Rochelle, Mamaroneck, Rye and Portchester, in Westchester County, and at Greenwich, Conn., the earthquake was both heard and felt very distinctly."

A dozen years later, on August 10, 1884, Pelham and much of Westchester County experienced another such earthquake -- this one significant. That day, a magnitude 5.2 quake centered off the shore of Far Rockaway, Queens shook the New York metropolitan region at about 2:00 p.m., followed by aftershocks as late as the following day. The initial shock was so great that a bell in White Plains was rung. Once again, according to the New York Times:

"[I]mmense trees were swayed to and fro. Houses trembled to their very foundations, shaking loose articles from their fastenings and causing general consternation among the inhabitants. People rushed from their houses to the streets, asking each other the cause of their own fright. The course of the earthquake was from the northwest to the southeast."

The same article noted that the earthquake was the fourth significant temblor to strike the region in 35 years, the others occurring in 1850, on August 7, 1868 and, as noted above, on July 11, 1872.

The New York Herald described the earthquake that day as follows:

"In Westchester county the shock was felt in every town and village, and while it lasted there was great consternation. People ran out of their houses, and some of the superstitious fell on their knees, fully believing that the judgment day had come.

"The shock was announced by a shaking of houses and a rattling of windows. Then a noise resembling the approach of a mighty wind was heard. The dwellings shook more violently and the inmates began to scamper for the open air. The sick suffered especially, and last evening many serious relapses through fright were reported by the physicians. The shock came at precisely seven minutes past two o'clock. It seemed to pass from east to west.

"In New Rochelle, Pelham, Mount Vernon, Port Chester, White Plains, Tarrytown, Sing Sing, Yonkers and Peekskill the shock was felt. At White Plains the shock was so great as to twice distinctly ring the gong in the hall door of the Orawaupum Hotel. Professor John Swinburne, how has boarded in the hotel for thirty years past, has taken great pains to select a very valuable collection of minerals, agates, rare stones, shells and specimens of all the ores and quartz known to the world. These he has in a glass case, which occupies one side of his room. When the shock came Professor Swinburne was asleep, but was awakened by the rattling of his mineraological specimens. When he examined the case he found many of the specimens displaced. Some had fallen from the shelves against the glass door and others had huddled together as if for protection.

"One gentleman in New Rochelle described the undulations as resembling the rapid rolling of a heavy cannon carriage over the bare floor of an upper room. He said the house in which he resided shook so that he thought it was coming down. The brick dwellings trembled more violently than the wooden ones, but, as far as heard from, no damage of any kind was done to property.

"From all along the Hudson River come reports of a similar experience to that just detailed. At Hudson two distinct shocks were felt at a quarter past two o'clock."

Source: THE SUBURBS IN A FLURRY. HOUSES EMPTIED, DINNERS ABANDONED AND THE SUPERSTITIOUS FRIGHTENED, N.Y. Herald, Aug. 11, 1884, p. 3, col. 3.

Could It Happen Again?

The 1884 earthquake was the last significant quake experienced in Pelham. That is not to say, however, that it was the last earthquake centered in the region. According to the United States Geological Survey, since 1974 there have been 18 earthquakes centered within 50 miles of southern Westchester County. They ranged from magnitude 2.0 to magnitude 4.0. Also according to the USGS, there is a 3.742% chance of a major earthquake centered within 50 miles of southern Westchester County within the next 50 years.

Nor should this surprise. Few may realize it, but only 13 miles from Pelham -- far beneath 125th Street in Manhattan -- lies the so-called "125th Street Fault Line." While it is nothing like major fault lines such as the "San Andreas Fault" on the west coast of the United States, the 125th Street Fault Line is still a concern to experts who recognize that population growth (as well as urban and suburban development) in the region since the late 19th century have increased the risks of substantial damage from major earthquakes in the region. Indeed, in a report entitled "Earthquake Loss Estimation Study for The New York City Area" published in 1999, experts from Princeton and Columbia concluded that:

"New York City's seismic risk exposure is of increasing concern. The New York City metropolitan area has been classified by the United States Geologic Survey (USGS) to the moderate level for potential earthquakes. . . . Risk is typically defined by three components: a hazard (the earthquake), the assets involved and the fragility of those assets. For New York City, the probability of a large earthquake is moderate, however, it becomes an area of high risk because of its tremendous assets and the fragility of its structures, which have not been seismically designed as most on the West Coast."

Moreover, recently a group of scientists and engineers who formed the "New York City Area Consortium for Earthquake Loss Mitigation" released a report concluding that a "catastrophic" earthquake with a magnitude of 6 or larger is possible in this region and estimating that a magnitude 6 earthquake striking the region at 2:00 p.m. would cause up to 1,170 deaths and up to $40 billion in damages.

Though a major temblor may never occur in our lifetimes in Pelham, if history is any indication, the region remains on "shaky ground" and faces further quakes.