A
couple of hundred thousand years ago, an M 7.2 earthquake shook what is
now New Hampshire. Just a few thousand years ago, an M 7.5 quake
ruptured just off the coast of Massachusetts. And then there’s New York.
Since
the first western settlers arrived there, the state has witnessed 200
quakes of magnitude 2.0 or greater, making it the third most seismically
active state east of the Mississippi (Tennessee and South Carolina are
ranked numbers one and two, respectively). About once a century, New
York has also experienced an M 5.0 quake capable of doing real damage.
The
most recent one near New York City occurred in August of 1884. Centered
off Long Island’s Rockaway Beach, it was felt over 70,000 square miles.
It also opened enormous crevices near the Brooklyn reservoir and
knocked down chimneys and cracked walls in Pennsylvania and Connecticut.
Police on the Brooklyn Bridge said it swayed “as if struck by a
hurricane” and worried the bridge’s towers would collapse. Meanwhile,
residents throughout New York and New Jersey reported sounds that varied
from explosions to loud rumblings, sometimes to comic effect. At the
funeral of Lewis Ingler, a small group of mourners were watching as the
priest began to pray. The quake cracked an enormous mirror behind the
casket and knocked off a display of flowers that had been resting on top
of it. When it began to shake the casket’s silver handles, the mourners
decided the unholy return of Lewis Ingler was more than they could take
and began flinging themselves out windows and doors.
Not
all stories were so light. Two people died during the quake, both
allegedly of fright. Out at sea, the captain of the brig Alice felt a
heavy lurch that threw him and his crew, followed by a shaking that
lasted nearly a minute. He was certain he had hit a wreck and was taking
on water.
A
day after the quake, the editors of The New York Times sought to allay
readers’ fear. The quake, they said, was an unexpected fluke never to be
repeated and not worth anyone’s attention: “History and the researches
of scientific men indicate that great seismic disturbances occur only
within geographical limits that are now well defined,” they wrote in an
editorial. “The northeastern portion of the United States . . . is not
within those limits.” The editors then went on to scoff at the
histrionics displayed by New York residents when confronted by the
quake: “They do not stop to reason or to recall the fact that
earthquakes here are harmless phenomena. They only know that the solid
earth, to whose immovability they have always turned with confidence
when everything else seemed transitory, uncertain, and deceptive, is
trembling and in motion, and the tremor ceases long before their
disturbed minds become tranquil.”
That’s the kind of thing that drives Columbia’s Heather Savage nuts.
Across
town, Charles Merguerian has been studying these faults the
old‐fashioned way: by getting down and dirty underground. He’s spent the
past forty years sloshing through some of the city’s muckiest places:
basements and foundations, sewers and tunnels, sometimes as deep as 750
feet belowground. His tools down there consist primarily of a pair of
muck boots, a bright blue hard hat, and a pickax. In public
presentations, he claims he is also ably abetted by an assistant hamster
named Hammie, who maintains his own website, which includes, among
other things, photos of the rodent taking down Godzilla.
That’s
just one example why, if you were going to cast a sitcom starring two
geophysicists, you’d want Savage and Merguerian to play the leading
roles. Merguerian is as eccentric and flamboyant as Savage is earnest
and understated. In his press materials, the former promises to arrive
at lectures “fully clothed.” Photos of his “lab” depict a dingy
porta‐john in an abandoned subway tunnel. He actively maintains an
archive of vintage Chinese fireworks labels at least as extensive as his
list of publications, and his professional website includes a
discography of blues tunes particularly suitable for earthquakes. He
calls female science writers “sweetheart” and somehow manages to do so
in a way that kind of makes them like it (although they remain
nevertheless somewhat embarrassed to admit it).
It’s
Merguerian’s boots‐on‐the‐ground approach that has provided much of the
information we need to understand just what’s going on underneath
Gotham. By his count, Merguerian has walked the entire island of
Manhattan: every street, every alley. He’s been in most of the tunnels
there, too. His favorite one by far is the newest water tunnel in
western Queens. Over the course of 150 days, Merguerian mapped all five
miles of it. And that mapping has done much to inform what we know about seismicity in New York.
Most
importantly, he says, it provided the first definitive proof of just
how many faults really lie below the surface there. And as the city
continues to excavate its subterranean limits, Merguerian is committed
to following closely behind. It’s a messy business.
Down
below the city, Merguerian encounters muck of every flavor and variety.
He power‐washes what he can and relies upon a diver’s halogen
flashlight and a digital camera with a very, very good flash to make up
the difference. And through this process, Merguerian has found thousands
of faults, some of which were big enough to alter the course of the
Bronx River after the last ice age.
His
is a tricky kind of detective work. The center of a fault is primarily
pulverized rock. For these New York faults, that gouge was the very
first thing to be swept away by passing glaciers. To do his work, then,
he’s primarily looking for what geologists call “offsets”—places where
the types of rock don’t line up with one another. That kind of
irregularity shows signs of movement over time—clear evidence of a
fault.
Merguerian has found a lot of them underneath New York City.
Each
time that occurred, the land currently known as the Mid‐Atlantic
underwent an accordion effect as it was violently folded into itself
again and again. The process created immense mountains that have eroded
over time and been further scoured by glaciers. What remains is a
hodgepodge of geological conditions ranging from solid bedrock to
glacial till to brittle rock still bearing the cracks of the collision.
And, says Merguerian, any one of them could cause an earthquake.
You don’t have to follow him belowground to find these fractures. Even with all the development in our most built‐up metropolis, evidence of these faults can be found everywhere—from 42nd Street to Greenwich Village. But if you want the starkest example of all, hop the 1 train at Times Square and head uptown to Harlem. Not
far from where the Columbia University bus collects people for the trip
to the Lamont‐Doherty Earth Observatory, the subway tracks seem to pop
out of the ground onto a trestle bridge before dropping back down to
earth. That, however, is just an illusion. What actually happens there
is that the ground drops out below the train at the site of one of New York’s largest faults. It’s known by geologists in the region as the Manhattanville or 125th Street Fault, and
it runs all the way across the top of Central Park and, eventually,
underneath Long Island City. Geologists have known about the fault since
1939, when the city undertook a massive subway mapping project, but it
wasn’t until recently that they confirmed its potential for a
significant quake.
In
our lifetimes, a series of small earthquakes have been recorded on the
Manhattanville Fault including, most recently, one on October 27, 2001.
Its epicenter was located around 55th and 8th—directly beneath the
original Original Soupman restaurant, owned by restaurateur Ali Yeganeh,
the inspiration for Seinfeld’s Soup Nazi. That fact delighted sitcom
fans across the country, though few Manhattanites were in any mood to
appreciate it.
The
October 2001 quake itself was small—about M 2.6—but the effect on
residents there was significant. Just six weeks prior, the city had been
rocked by the 9/11 terrorist attacks that brought down the World Trade
Center towers. The team at Lamont‐Doherty has maintained a seismic
network in the region since the ’70s. They registered the collapse of
the first tower at M 2.1. Half an hour later, the second tower crumbled
with even more force and registered M 2.3. In a city still shocked by
that catastrophe, the early‐morning October quake—several times greater
than the collapse of either tower—jolted millions of residents awake
with both reminders of the tragedy and fear of yet another attack. 9‐1‐1
calls overwhelmed dispatchers and first responders with reports of
shaking buildings and questions about safety in the city. For
seismologists, though, that little quake was less about foreign threats
to our soil and more about the possibility of larger tremors to come.
“Gee whiz!” He laughs when I pose this question. “That’s the holy grail of seismicity, isn’t it?”
He
says all we can do to answer that question is “take the pulse of what’s
gone on in recorded history.” To really have an answer, we’d need to
have about ten times as much data as we do today. But from what he’s
seen, the faults below New York are very much alive.
“These guys are loaded,” he tells me.
He
says he is also concerned about new studies of a previously unknown
fault zone known as the Ramapo that runs not far from the city. Savage
shares his concerns. They both think it’s capable of an M 6.0 quake or
even higher—maybe even a 7.0. If and when, though, is really anybody’s
guess.
“We literally have no idea what’s happening in our backyard,” says Savage.
What
we do know is that these quakes have the potential to do more damage
than similar ones out West, mostly because they are occurring on far
harder rock capable of propagating waves much farther. And
because these quakes occur in places with higher population densities,
these eastern events can affect a lot more people. Take the 2011
Virginia quake: Although it was only a moderate one, more Americans felt
it than any other one in our nation’s history.
That’s
the thing about the East Coast: Its earthquake hazard may be lower than
that of the West Coast, but the total effect of any given quake is much
higher. Disaster
specialists talk about this in terms of risk, and they make sense of it
with an equation that multiplies the potential hazard of an event by
the cost of damage and the number of people harmed. When you take all of
those factors into account, the earthquake risk in New York is much
greater than, say, that in Alaska or Hawaii or even a lot of the area
around the San Andreas Fault.
Merguerian
has been sounding the alarm about earthquake risk in the city since the
’90s. He admits he hasn’t gotten much of a response. He says that when
he first proposed the idea of seismic risk in New York City, his fellow
scientists “booed and threw vegetables” at him. He volunteered his
services to the city’s Office of Emergency Management but says his
original offer also fell on deaf ears.
“So I backed away gently and went back to academia.”
Today, he says, the city isn’t much more responsive, but he’s getting a much better response from his peers.
He’s
glad for that, he says, but it’s not enough. If anything, the events of
9/11, along with the devastation caused in 2012 by Superstorm Sandy,
should tell us just how bad it could be there.
He
and Savage agree that what makes the risk most troubling is just how
little we know about it. When it comes right down to it, intraplate
faults are the least understood. Some scientists think they might be
caused by mantle flow deep below the earth’s crust. Others think they
might be related to gravitational energy. Still others think quakes
occurring there might be caused by the force of the Atlantic ridge as it
pushes outward. Then again, it could be because the land is springing
back after being compressed thousands of years ago by glaciers (a
phenomenon geologists refer to as seismic rebound).
Adapted
from Quakeland: On the Road to America’s Next Devastating Earthquake by
Kathryn Miles, published by Dutton, an imprint of Penguin Publishing
Group, a division of Penguin Random House, LLC. Copyright © 2017 by
Kathryn Miles.
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