Real Risk, Few Precautions (Revelation 6:12)

 

Eastern Quakes: Real Risk, Few Precautions

By WILLIAM K. STEVENS

Published: October 24, 1989

AN EARTHQUAKE as powerful as the one that struck northern California last week could occur almost anywhere along the East Coast, experts say. And if it did, it would probably cause far more destruction than the West Coast quake.

The chances of such an occurrence are much less in the East than on the West Coast. Geologic stresses in the East build up only a hundredth to a thousandth as fast as in California, and this means that big Eastern quakes are far less frequent. Scientists do not really know what the interval between them might be, nor are the deeper-lying geologic faults that cause them as accessible to study. So seismologists are at a loss to predict when or where they will strike.

But they do know that a temblor with a magnitude estimated at 7 on the Richter scale – about the same magnitude as last week’s California quake – devastated Charleston, S.C., in 1886. And after more than a decade of study, they also know that geologic structures similar to those that caused the Charleston quake exist all along the Eastern Seaboard.

For this reason, ”we can’t preclude that a Charleston-sized earthquake might occur anywhere along the East Coast,” said David Russ, the assistant chief geologist of the United States Geological Survey in Reston, Va. ”It could occur in Washington. It could occur in New York.”

If that happens, many experts agree, the impact will probably be much greater than in California. Easterners, unlike Californians, have paid very little attention to making buildings and other structures earthquake-proof or earthquake-resistant. ”We don’t have that mentality here on the East Coast,” said Robert Silman, a New York structural engineer whose firm has worked on 3,800 buildings in the metropolitan area.

Moreover, buildings, highways, bridges, water and sewer systems and communications networks in the East are all older than in the West and consequently more vulnerable to damage. Even under normal conditions, for instance, water mains routinely rupture in New York City.

The result, said Dr. John Ebel, a geophysicist who is the assistant director of Boston College’s Weston Observatory, is that damage in the East would probably be more widespread, more people could be hurt and killed, depending on circumstances like time of day, and ”it would probably take a lot longer to get these cities back to useful operating levels.”

On top of this, scientists say, an earthquake in the East can shake an area 100 times larger than a quake of the same magnitude in California. This is because the earth’s crust is older, colder and more brittle in the East and tends to transmit seismic energy more efficiently. ”If you had a magnitude 7 earthquake and you put it halfway between New York City and Boston,” Dr. Ebel said, ”you would have the potential of doing damage in both places,” not to mention cities like Hartford and Providence.

Few studies have been done of Eastern cities’ vulnerability to earthquakes. But one, published last June in The Annals of the New York Academy of Sciences, calculated the effects on New York City of a magnitude 6 earthquake. That is one-tenth the magnitude of last week’s California quake, but about the same as the Whittier, Calif., quake two years ago.

The study found that such an earthquake centered 17 miles southeast of City Hall, off Rockaway Beach, would cause $11 billion in damage to buildings and start 130 fires. By comparison, preliminary estimates place the damage in last week’s California disaster at $4 billion to $10 billion. If the quake’s epicenter were 11 miles southeast of City Hall, the study found, there would be about $18 billion in damage; if 5 miles, about $25 billion.

No estimates on injuries or loss of life were made. But a magnitude 6 earthquake ”would probably be a disaster unparalleled in New York history,” wrote the authors of the study, Charles Scawthorn and Stephen K. Harris of EQE Engineering in San Francisco.

The study was financed by the National Center for Earthquake Engineering Research at the State University of New York at Buffalo. The research and education center, supported by the National Science Foundation and New York State, was established in 1986 to help reduce damage and loss of life from earthquakes.

The study’s postulated epicenter of 17 miles southeast of City Hall was the location of the strongest quake to strike New York since it has been settled, a magnitude 5 temblor on Aug. 10, 1884. That 1884 quake rattled bottles and crockery in Manhattan and frightened New Yorkers, but caused little damage. Seismologists say a quake of that order is likely to occur within 50 miles of New York City every 300 years. Quakes of magnitude 5 are not rare in the East. The major earthquake zone in the eastern half of the country is the central Mississippi Valley, where a huge underground rift causes frequent geologic dislocations and small temblors. The most powerful quake ever known to strike the United States occurred at New Madrid, Mo., in 1812. It was later estimated at magnitude 8.7 and was one of three quakes to strike that area in 1811-12, all of them stronger than magnitude 8. They were felt as far away as Washington, where they rattled chandeliers, Boston and Quebec.

Because the New Madrid rift is so active, it has been well studied, and scientists have been able to come up with predictions for the central Mississippi valley, which includes St. Louis and Memphis. According to Dr. Russ, there is a 40 to 63 percent chance that a quake of magnitude 6 will strike that area between now and the year 2000, and an 86 to 97 percent chance that it will do so by 2035. The Federal geologists say there is a 1 percent chance or less of a quake greater than magnitude 7 by 2000, and a 4 percent chance or less by 2035.

Elsewhere in the East, scientists are limited in their knowledge of probabilities partly because faults that could cause big earthquakes are buried deeper in the earth’s crust. In contrast to California, where the boundary between two major tectonic plates creates the San Andreas and related faults, the eastern United States lies in the middle of a major tectonic plate. Its faults are far less obvious, their activity far more subtle, and their slippage far slower. 

Any large earthquake would be ”vastly more serious” in the older cities of the East than in California, said Dr. Tsu T. Soong, a professor of civil engineering at the State University of New York at Buffalo who is a researcher in earthquake-mitigation technology at the National Center for Earthquake Engineering Research. First, he said, many buildings are simply older, and therefore weaker and more vulnerable to collapse. Second, there is no seismic construction code in most of the East as there is in California, where such codes have been in place for decades.

The vulnerability is evident in many ways. ”I’m sitting here looking out my window,” said Mr. Silman, the structural engineer in New York, ”and I see a bunch of water tanks all over the place” on rooftops. ”They are not anchored down at all, and it’s very possible they would fall in an earthquake.”

 Many brownstones, he said, constructed as they are of unreinforced masonry walls with wood joists between, ”would just go like a house of cards.” Unreinforced masonry, in fact, is the single most vulnerable structure, engineers say. Such buildings are abundant, even predominant, in many older cities. The Scawthorn-Harris study reviewed inventories of all buildings in Manhattan as of 1972 and found that 28,884, or more than half, were built of unreinforced masonry. Of those, 23,064 were three to five stories high.

Buildings of reinforced masonry, reinforced concrete and steel would hold up much better, engineers say, and wooden structures are considered intrinsically tough in ordinary circumstances. The best performers, they say, would probably be skyscrapers built in the last 20 years. As Mr. Silman explained, they have been built to withstand high winds, and the same structural features that enable them to do so also help them resist an earthquake’s force. But even these new towers have not been provided with the seismic protections required in California and so are more vulnerable than similar structures on the West Coast.

Buildings in New York are not generally constructed with such seismic protections as base-isolated structures, in which the building is allowed to shift with the ground movement; or with flexible frames that absorb and distribute energy through columns and beams so that floors can flex from side to side, or with reinforced frames that help resist distortion.

”If you’re trying to make a building ductile – able to absorb energy – we’re not geared to think that way,” said Mr. Silman.

New York buildings also contain a lot of decorative stonework, which can be dislodged and turned into lethal missiles by an earthquake. In California, building codes strictly regulate such architectural details.

Manhattan does, however, have at least one mitigating factor: ”We are blessed with this bedrock island,” said Mr. Silman. ”That should work to our benefit; we don’t have shifting soils. But there are plenty of places that are problem areas, particularly the shoreline areas,” where landfills make the ground soft and unstable.

As scientists have learned more about geologic faults in the Northeast, the nation’s uniform building code – the basic, minimum code followed throughout the country – has been revised accordingly. Until recently, the code required newly constructed buildings in New York City to withstand at least 19 percent of the side-to-side seismic force that a comparable building in the seismically active areas of California must handle. Now the threshold has been raised to 25 percent.

New York City, for the first time, is moving to adopt seismic standards as part of its own building code. Local and state building codes can and do go beyond the national code. Charles M. Smith Jr., the city Building Commissioner, last spring formed a committee of scientists, engineers, architects and government officials to recommend the changes.

”They all agree that New York City should anticipate an earthquake,” Mr. Smith said. As to how big an earthquake, ”I don’t think anybody would bet on a magnitude greater than 6.5,” he said. ”I don’t know,” he added, ”that our committee will go so far as to acknowledge” the damage levels in the Scawthorn-Harris study, characterizing it as ”not without controversy.”

For the most part, neither New York nor any other Eastern city has done a detailed survey of just how individual buildings and other structures would be affected, and how or whether to modify them.

”The thing I think is needed in the East is a program to investigate all the bridges” to see how they would stand up to various magnitudes of earthquake,” said Bill Geyer, the executive vice president of the New York engineering firm of Steinman, Boynton, Gronquist and Birdsall, which is rehabilitating the cable on the Williamsburg Bridge. ”No one has gone through and done any analysis of the existing bridges.”

In general, he said, the large suspension bridges, by their nature, ”are not susceptible to the magnitude of earthquake you’d expect in the East.” But the approaches and side spans of some of them might be, he said, and only a bridge-by-bridge analysis would tell. Nor, experts say, are some elevated highways in New York designed with the flexibility and ability to accommodate motion that would enable them to withstand a big temblor.

Tunnels Vulnerable

The underground tunnels that carry travelers under the rivers into Manhattan, those that contain the subways and those that carry water, sewers and natural gas would all be vulnerable to rupture, engineers say. The Lincoln, Holland, PATH and Amtrak tunnels, for instance, go from bedrock in Manhattan to soft soil under the Hudson River to bedrock again in New Jersey, said Mark Carter, a partner in Raamot Associates, geotechnical engineers specializing in soils and foundations.

Likewise, he said, subway tunnels between Manhattan and Queens go from hard rock to soft soil to hard rock on Roosevelt Island, to soft soil again and back to rock. The boundaries between soft soil and rock are points of weakness, he said.

”These structures are old,” he said, ”and as far as I know they have not been designed for earthquake loadings.”

Even if it is possible to survey all major buildings and facilities to determine what corrections can be made, cities like New York would then face a major decision: Is it worth spending the money to modify buildings and other structures to cope with a quake that might or might not come in 100, or 200 300 years or more?

”That is a classical problem” in risk-benefit analysis, said Dr. George Lee, the acting director of the Earthquake Engineering Research Center in Buffalo. As more is learned about Eastern earthquakes, he said, it should become ”possible to talk about decision-making.” But for now, he said, ”I think it’s premature for us to consider that question.”

The Nuclear Meltdown at the Sixth Seal (Revelation 6:12)

NYS agencies urge more scrutiny of Algonquin pipeline at Indian Point

Jorge Fitz-Gibbon, Rockland/Westchester Journal News

A group of residents opposed to the Algonquin gas pipeline project meet at Somers Intermediate School Monday, Dec. 4, 2017. Peter Carr/The Journal News

State asks Federal Energy Regulatory Commission for more steps ‘to minimize risk and protect public safety’ near the Buchanan plant

Several New York state agencies are urging the Federal Energy Regulatory Commission to institute additional safety measures on the Algonquin Pipeline portions near the Indian Point nuclear reactor.

In a letter to the commission, officials from the state health, public safety, environmental conservation and homeland security agencies called for “additional scrutiny and monitoring” to minimize risks near the Buchanan plant.

“While the probability of pipeline incidents is low, the proximity to the Indian Point nuclear plant makes the potential consequences of such an event very significant,” the state agencies said in a joint statement. “Additional scrutiny and monitoring to better understand and reduce risks associated with the Algonquin pipelines is warranted.”

Pipeline owner Enbridge is in the midst of expanding the half-century old natural gas pipeline from Pennsylvania, through Westchester, Rockland and Putnam counties, and north into New England.

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Activists gathered in front of Governor Andrew Cuomo’s house in New Castle on Sunday to raise concerns about the Algonquin Pipeline project and other environmental issues. (Photo: Kurt Beebe for The Journal News)

Work done so far includes a new section through Stony Point, under the Hudson River, into Verplanck and near the Indian Point Energy Center.

The plan has sparked protests throughout the pipe’s path.

On Friday, the state agencies asked the federal commission for additional safety measures near the Indian Point property, including:

• Ensure that Enbridge will not be allowed to send additional natural gas at higher pressure through the pipeline to meet high demand for gas in the Northeast.

A map of the Algonquin pipeline expansion project (Photo: Courtesy Spectra Energy)• Require regular testing to ensure that valves on 26-inch, 30-inch and 42-inch pipelines near Indian Point can be closed remotely within three minutes of an event.

• The commission should work with the Nuclear Regulatory Commission to examine Entergy Corp.’s decommission plan for Indian Point “to determine potential impacts to the original Algonquin pipelines.”

History Says Expect The Sixth Seal In New York (Revelation 6:12)

History Says New York Is Earthquake Prone

If the past is any indication, New York can be hit by an earthquake, claims John Armbruster, a seismologist at Columbia University’s Lamont-Doherty Earth Observatory.

Based on historical precedent, Armbruster says the New York City metro area is susceptible to an earthquake of at least a magnitude of 5.0 once a century.

According to the New York Daily News, Lynn Skyes, lead author of a recent study by seismologists at the Lamont-Doherty Earth Observatory adds that a magnitude-6 quake hits the area about every 670 years, and magnitude-7 every 3,400 years.

A 5.2-magnitude quake shook New York City in 1737 and another of the same severity hit in 1884.

Tremors were felt from Maine to Virginia.

There are several fault lines in the metro area, including one along Manhattan’s 125th St. – which may have generated two small tremors in 1981 and may have been the source of the major 1737 earthquake, says Armbruster.

There’s another fault line on Dyckman St. and one in Dobbs Ferry in nearby Westchester County.

“The problem here comes from many subtle faults,” explained Skyes after the study was published.

He adds: “We now see there is earthquake activity on them. Each one is small, but when you add them up, they are probably more dangerous than we thought.”

“Considering population density and the condition of the region’s infrastructure and building stock, it is clear that even a moderate earthquake would have considerable consequences in terms of public safety and economic impact,” says the New York City Area Consortium for Earthquake Loss Mitigation on its website.

Armbruster says a 5.0-magnitude earthquake today likely would result in casualties and hundreds of millions of dollars in damage.

“I would expect some people to be killed,” he notes.

The scope and scale of damage would multiply exponentially with each additional tick on the Richter scale. (ANI)

2018: The Year of the Sixth Seal (Revelation 6:12)

Sloshing of Earth’s core may spike major earthquakes

By Paul VoosenOct. 30, 2017 , 1:45 PM

The number of major earthquakes, like the magnitude-7 one that devastated Haiti in 2010, seems to be correlated with minute fluctuations in day length.

SEATTLE—The world doesn’t stop spinning. But every so often, it slows down. For decades, scientists have charted tiny fluctuations in the length of Earth’s day: Gain a millisecond here, lose a millisecond there. Last week at the annual meeting of the Geological Society of America here, two geophysicists argued that these minute changes could be enough to influence the timing of major earthquakes—and potentially help forecast them.

During the past 100 years, Earth’s slowdowns have correlated surprisingly well with periods with a global increase in magnitude-7 and larger earthquakes, according to Roger Bilham of the University of Colorado (CU) in Boulder and Rebecca Bendick at the University of Montana in Missoula. Usefully, the spike, which adds two to five more quakes than typical, happens well after the slow-down begins. “The Earth offers us a 5-years heads up on future earthquakes, which is remarkable,” says Bilham, who presented the work.

Most seismologists agree that earthquake prediction is a minefield. And so far, Bilham and Bendick have only fuzzy, hard-to-test ideas about what might cause the pattern they found. But the finding is too provocative to ignore, other researchers say. “The correlation they’ve found is remarkable, and deserves investigation,” says Peter Molnar, a geologist also at CU.

The research started as a search for synchrony in earthquake timing. Individual oscillators, be they fireflies, heart muscles, or metronomes, can end up vibrating in synchrony as a result of some kind of cross-talk—or some common influence. To Bendick, it didn’t seem a far jump to consider the faults that cause earthquakes, with their cyclical buildup of strain and violent discharge, as “really noisy, really crummy oscillators,” she says. She and Bilham dove into the data, using the only complete earthquake catalog for the past 100 years: magnitude-7 and larger earthquakes.

In work published in August in Geophysical Research Letters they reported two patterns: First, major quakes appeared to cluster in time

—although not in space. And second, the number of large earthquakes seemed to peak at 32-year intervals. The earthquakes could be somehow talking to each other, or an external force could be nudging the earth into rupture.

Exploring such global forces, the researchers eventually discovered the match with the length of day. Although weather patterns such as El Nino can drive day length to vary back and forth by a millisecond over a year or more, a periodic, decades-long fluctuation of several milliseconds—in particular, its point of peak slow down about every three decades or so—lined up with the quake trend perfectly. “Of course that seems sort of crazy,” Bendick says. But maybe it isn’t. When day length changes over decades, Earth’s magnetic field also develops a temporary ripple. Researchers think slight changes in the flow of the molten iron of the outer core may be responsible for both effects. Just what happens is uncertain—perhaps a bit of the molten outer core sticks to the mantle above. That might change the flow of the liquid metal, altering the magnetic field, and transfer enough momentum between the mantle and the core to affect day length.

Seismologists aren’t used to thinking about the planet’s core, buried 2900 kilometers beneath the crust where quakes happen. But they should, Bilham said during his talk here. The core is “quite close to us. It’s closer than New York from here,” he said.

At the equator, Earth spins 460 meters per second. Given this high velocity, it’s not absurd to think that a slight mismatch in speed between the solid crust and mantle and the liquid core could translate into a force somehow nudging quakes into synchrony, Molnar says. Of course, he adds, “It might be nonsense.” But the evidence for some kind of link is compelling, says geophysicist Michael Manga of the University of California, Berkeley. “I’ve worked on earthquakes triggered by seasonal variation, melting snow. His correlation is much better than what I’m used to seeing.”

One way or another, says James Dolan, a geologist at the University of Southern California in Los Angeles, “we’re going to know in 5 years.” That’s because Earth’s rotation began a periodic slow-down 4-plus years ago. Beginning next year, Earth should expect five more major earthquakes a year than average—between 17 to 20 quakes, compared with the anomalously low four so far this year. If the pattern holds, it will put a new spin on earthquake forecasting.

doi:10.1126/science.aar3598

Quakeland: New York and the Sixth Seal (Revelation 6:12)

Quakeland: On the Road to America’s Next Devastating Earthquake

Roger Bilham

Given recent seismic activity — political as well as geological — it’s perhaps unsurprising that two books on earthquakes have arrived this season. One is as elegant as the score of a Beethoven symphony; the other resembles a diary of conversations overheard during a rock concert. Both are interesting, and both relate recent history to a shaky future.

Journalist Kathryn Miles’s Quakeland is a litany of bad things that happen when you provoke Earth to release its invisible but ubiquitous store of seismic-strain energy, either by removing fluids (oil, water, gas) or by adding them in copious quantities (when extracting shale gas in hydraulic fracturing, also known as fracking, or when injecting contaminated water or building reservoirs). To complete the picture, she describes at length the bad things that happen during unprovoked natural earthquakes. As its subtitle hints, the book takes the form of a road trip to visit seismic disasters both past and potential, and seismologists and earthquake engineers who have first-hand knowledge of them. Their colourful personalities, opinions and prejudices tell a story of scientific discovery and engineering remedy.

Miles poses some important societal questions. Aside from human intervention potentially triggering a really damaging earthquake, what is it actually like to live in neighbourhoods jolted daily by magnitude 1–3 earthquakes, or the occasional magnitude 5? Are these bumps in the night acceptable? And how can industries that perturb the highly stressed rocks beneath our feet deny obvious cause and effect? In 2015, the Oklahoma Geological Survey conceded that a quadrupling of the rate of magnitude-3 or more earthquakes in recent years, coinciding with a rise in fracking, was unlikely to represent a natural process. Miles does not take sides, but it’s difficult for the reader not to.

She visits New York City, marvelling at subway tunnels and unreinforced masonry almost certainly scheduled for destruction by the next moderate earthquake in the vicinity. She considers the perils of nuclear-waste storage in Nevada and Texas, and ponders the risks to Idaho miners of rock bursts — spontaneous fracture of the working face when the restraints of many million years of confinement are mined away. She contemplates the ups and downs of the Yellowstone Caldera — North America’s very own mid-continent supervolcano — and its magnificently uncertain future. Miles also touches on geothermal power plants in southern California’s Salton Sea and elsewhere; the vast US network of crumbling bridges, dams and oil-storage farms; and the magnitude 7–9 earthquakes that could hit California and the Cascadia coastline of Oregon and Washington state this century. Amid all this doom, a new elementary school on the coast near Westport, Washington, vulnerable to inbound tsunamis, is offered as a note of optimism. With foresight and much persuasion from its head teacher, it was engineered to become an elevated safe haven.

Miles briefly discusses earthquake prediction and the perils of getting it wrong (embarrassment in New Madrid, Missouri, where a quake was predicted but never materialized; prison in L’Aquila, Italy, where scientists failed to foresee a devastating seismic event) and the successes of early-warning systems, with which electronic alerts can be issued ahead of damaging seismic waves. Yes, it’s a lot to digest, but most of the book obeys the laws of physics, and it is a engaging read. One just can’t help wishing that Miles’s road trips had taken her somewhere that wasn’t a disaster waiting to happen.

Catastrophic damage in Anchorage, Alaska, in 1964, caused by the second-largest earthquake in the global instrumental record.

In The Great Quake, journalist Henry Fountain provides us with a forthright and timely reminder of the startling historical consequences of North America’s largest known earthquake, which more than half a century ago devastated southern Alaska. With its epicentre in Prince William Sound, the 1964 quake reached magnitude 9.2, the second largest in the global instrumental record. It released more energy than either the 2004 Sumatra–Andaman earthquake or the 2011 Tohoku earthquake off Japan; and it generated almost as many pages of scientific commentary and description as aftershocks. Yet it has been forgotten by many.

The quake was scientifically important because it occurred at a time when plate tectonics was in transition from hypothesis to theory. Fountain expertly traces the theory’s historical development, and how the Alaska earthquake was pivotal in nailing down one of the most important predictions. The earthquake caused a fjordland region larger than England to subside, and a similarly huge region of islands offshore to rise by many metres; but its scientific implications were not obvious at the time. Eminent seismologists thought that a vertical fault had slipped, drowning forests and coastlines to its north and raising beaches and islands to its south. But this kind of fault should have reached the surface, and extended deep into Earth’s mantle. There was no geological evidence of a monster surface fault separating these two regions, nor any evidence for excessively deep aftershocks. The landslides and liquefied soils that collapsed houses, and the tsunami that severely damaged ports and infrastructure, offered no clues to the cause.

“Previous earthquakes provide clear guidance about present-day vulnerability.” The hero of The Great Quake is the geologist George Plafker, who painstakingly mapped the height reached by barnacles lifted out of the intertidal zone along shorelines raised by the earthquake, and documented the depths of drowned forests. He deduced that the region of subsidence was the surface manifestation of previously compressed rocks springing apart, driving parts of Alaska up and southwards over the Pacific Plate. His finding confirmed a prediction of plate tectonics, that the leading edge of the Pacific Plate plunged beneath the southern edge of Alaska along a gently dipping thrust fault. That observation, once fully appreciated, was applauded by the geophysics community.

Fountain tells this story through the testimony of survivors, engineers and scientists, interweaving it with the fascinating history of Alaska, from early discovery by Europeans to purchase from Russia by the United States in 1867, and its recent development. Were the quake to occur now, it is not difficult to envisage that with increased infrastructure and larger populations, the death toll and price tag would be two orders of magnitude larger than the 139 fatalities and US$300-million economic cost recorded in 1964.

What is clear from these two books is that seismicity on the North American continent is guaranteed to deliver surprises, along with unprecedented economic and human losses. Previous earthquakes provide clear guidance about the present-day vulnerability of US infrastructure and populations. Engineers and seismologists know how to mitigate the effects of future earthquakes (and, in mid-continent, would advise against the reckless injection of waste fluids known to trigger earthquakes). It is merely a matter of persuading city planners and politicians that if they are tempted to ignore the certainty of the continent’s seismic past, they should err on the side of caution when considering its seismic future.

Earthquake Assessment For The Sixth Seal (Revelation 6:12)

Earthquake Risk in New Jersey

by Daniel R. Dombroski, Jr.

A 10–fold increase in amplitude represents about a 32–fold increase in energy released for the same duration of shaking. The best known magnitude scale is one designed by C.F. Richter in 1935 for west coast earthquakes.

In New Jersey, earthquakes are measured with seismographs operated by the Lamont–Doherty Earth Observatory of Columbia University and the Delaware Geological Survey.

An earthquake’s intensity is determined by observing its effects at a particular place on the Earth’s surface. Intensity depends on the earthquake’s magnitude, the distance from the epicenter, and local geology. These scales are based on reports of people awakening, felt movements, sounds, and visible effects on structures and landscapes. The most commonly used scale in the United States is the Modified Mercalli Intensity Scale, and its values are usually reported in Roman numerals to distinguish them from magnitudes.

Past damage in New Jersey

New Jersey doesn’t get many earthquakes, but it does get some. Fortunately most are small. A few New Jersey earthquakes, as well as a few originating outside the state, have produced enough damage to warrant the concern of planners and emergency managers.

Damage in New Jersey from earthquakes has been minor: items knocked off shelves, cracked plaster and masonry, and fallen chimneys. Perhaps because no one was standing under a chimney when it fell, there are no recorded earthquake–related deaths in New Jersey. We will probably not be so fortunate in the future.

Area Affected by Eastern Earthquakes

Although the United States east of the Rocky Mountains has fewer and generally smaller earthquakes than the West, at least two factors  increase the earthquake risk in New Jersey and the East. Due to geologic differences, eastern earthquakes effect areas ten times larger than western ones of the same magnitude. Also, the eastern United States is more densely populated, and New Jersey is the most densely populated state in the nation.

Geologic Faults and Earthquakes in New Jersey

Although there are many faults in New Jersey, the Ramapo Fault, which separates the Piedmont and Highlands Physiographic Provinces, is the best known. In 1884 it was blamed for a damaging New York City earthquake simply because it was the only large fault mapped at the time. Subsequent investigations have shown the 1884 earthquake epicenter was actually located in Brooklyn, New York, at least 25 miles from the Ramapo Fault.

However, numerous minor earthquakes have been recorded in the Ramapo Fault Zone, a 10 to 20 mile wide area lying adjacent to, and west of, the actual fault.

More recently, in the 1970’s and early 1980’s, earthquake risk along the Ramapo Fault received attention because of its proximity to the Indian Point, New York, Nuclear Power Generating Station. East of the Rocky Mountains (including New Jersey), earthquakes do not break the ground surface. Their focuses lie at least a few miles below the Earth’s surface, and their locations are determined by interpreting seismographic records. Geologic fault lines seen on the surface today are evidence of ancient events. The presence or absence of mapped faults (fault lines) does not denote either a seismic hazard or the lack of one, and earthquakes can occur anywhere in New Jersey.

Frequency of Damaging Earthquakes in New Jersey

Records for the New York City area, which have been kept for 300 years, provide good information

for estimating the frequency of earthquakes in New Jersey.

Earthquakes with a maximum intensity of VII (see table DamagingEarthquakes Felt in New Jersey )have occurred in the New York City area in 1737, 1783, and 1884. One intensity VI, four intensity V’s, and at least three intensity III shocks have also occurred in the New York area over the last 300 years.

The time–spans between the intensity VII earthquakes were 46 and 101 years. This, and data for the smaller–intensity quakes, implies a return period of 100 years or less, and suggests New Jersey is overdue for a moderate earthquake like the one of 1884.

Buildings and Earthquakes

The 1995 earthquake in Kobe, Japan, is an example of what might happen in New Jersey in a similar quake. It registered a magnitude 7.2 on the Richter scale and produced widespread destruction. But it was the age of construction, soil and foundation condition, proximity to the fault, and type of structure that were the major determining factors in the performance of each building. Newer structures, built to the latest construction standards, appeared to perform relatively well, generally ensuring the life safety of occupants.

New Jersey’s building code has some provisions for earthquake–resistant design. But there are no requirements for retrofitting existing buildingsnot even for unreinforced masonry structures that are most vulnerable to earthquake damage. Housing of this type is common in New Jersey’s crowded urban areas. If an earthquake the size of New York City’s 1884 quake (magnitude 5.5) were to occur today, severe damage would result. Fatalities would be likely.

Structures have collapsed in New Jersey without earthquakes; an earthquake would trigger many more. Building and housing codes need to be updated and strictly enforced to properly prepare for inevitable future earthquakes.

A Lack Of Vigilance Before The Sixth Seal (Revelation 6)

Faults Underlying Exercise Vigilant Guard

Story by: (Author NameStaff Sgt. Raymond Drumsta – 138th Public Affairs Detachment

Dated: Thu, Nov 5, 2009

This map illustrates the earthquake fault lines in Western New York. An earthquake in the region is a likely event, says University of Buffalo Professor Dr. Robert Jacobi.

TONAWANDA, NY — An earthquake in western New York, the scenario that Exercise Vigilant Guard is built around, is not that far-fetched, according to University of Buffalo geology professor Dr. Robert Jacobi.

When asked about earthquakes in the area, Jacobi pulls out a computer-generated state map, cross-hatched with diagonal lines representing geological faults.

The faults show that past earthquakes in the state were not random, and could occur again on the same fault systems, he said.

“In western New York, 6.5 magnitude earthquakes are possible,” he said.

This possibility underlies Exercise Vigilant Guard, a joint training opportunity for National Guard and emergency response organizations to build relationships with local, state, regional and federal partners against a variety of different homeland security threats including natural disasters and potential terrorist attacks.

The exercise was based on an earthquake scenario, and a rubble pile at the Spaulding Fibre site here was used to simulate a collapsed building. The scenario was chosen as a result of extensive consultations with the earthquake experts at the University of Buffalo’s Multidisciplinary Center for Earthquake Engineering Research (MCEER), said Brig. Gen. Mike Swezey, commander of 53rd Troop Command, who visited the site on Monday.

Earthquakes of up to 7 magnitude have occurred in the Northeastern part of the continent, and this scenario was calibrated on the magnitude 5.9 earthquake which occurred in Saguenay, Quebec in 1988, said Jacobi and Professor Andre Filiatrault, MCEER director.

“A 5.9 magnitude earthquake in this area is not an unrealistic scenario,” said Filiatrault.

Closer to home, a 1.9 magnitude earthquake occurred about 2.5 miles from the Spaulding Fibre site within the last decade, Jacobi said. He and other earthquake experts impaneled by the Atomic Energy Control Board of Canada in 1997 found that there’s a 40 percent chance of 6.5 magnitude earthquake occurring along the Clareden-Linden fault system, which lies about halfway between Buffalo and Rochester, Jacobi added.

Jacobi and Filiatrault said the soft soil of western New York, especially in part of downtown Buffalo, would amplify tremors, causing more damage.

“It’s like jello in a bowl,” said Jacobi.

The area’s old infrastructure is vulnerable because it was built without reinforcing steel, said Filiatrault. Damage to industrial areas could release hazardous materials, he added.

“You’ll have significant damage,” Filiatrault said.

Exercise Vigilant Guard involved an earthquake’s aftermath, including infrastructure damage, injuries, deaths, displaced citizens and hazardous material incidents. All this week, more than 1,300 National Guard troops and hundreds of local and regional emergency response professionals have been training at several sites in western New York to respond these types of incidents.

Jacobi called Exercise Vigilant Guard “important and illuminating.”

“I’m proud of the National Guard for organizing and carrying out such an excellent exercise,” he said.

Training concluded Thursday.

Brace Yourselves for the Sixth Seal (Revelation 6)

Brace Yourselves, New Yorkers, You’re Due for a Major Quake

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.

New York, she says, is positively vivisected by faults. Most of them fall into two groups—those running northeast and those running northwest. Combined they create a brittle grid underlying much of Manhattan.

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.

These faults, he says, do a lot to explain the geological history of Manhattan and the surrounding area. They were created millions of years ago, when what is now the East Coast was the site of a violent subduction zone not unlike those present now in the Pacific’s Ring of Fire.

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.

Remember: The Big Apple has experienced an M 5.0 quake about every hundred years. The last one was that 1884 event. And that, says Merguerian, means the city is overdue. Just how overdue?

“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).

“We just have no consciousness towards earthquakes in the eastern United States,” says Merguerian. “And that’s a big mistake.”

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.

NYC earthquake risk: the Sixth Seal (Revelation 6:12)

NYC earthquake risk: Could Staten Island be heavily impacted?

By Ann Marie Barron

Updated May 16, 4:31 AM; Posted May 16, 4:00 AM

Rubble litters Main Street after an earthquake struck Sunday, Aug. 24, 2014, in Napa, Calif. A report by the U.S. Geological Survey outlines the differences between the effect of an earthquake in the West vs. one in the East. (AP Photo/Ben Margot)

STATEN ISLAND, N.Y. – While scientists say it’s impossible to predict when or if an earthquake will occur in New York City, they say that smaller structures — like Staten Island’s bounty of single-family homes — will suffer more than skyscrapers if it does happen.

“Earthquakes in the East tend to cause higher-frequency shaking — faster back-and-forth motion — compared to similar events in the West,” according to a report by the U.S. Geological Survey (USGS), published on its website recently “Shorter structures are more susceptible to damage during fast shaking, whereas taller structures are more susceptible during slow shaking.”

DIFFERENCES IN INTENSITY

The report, “East vs West Coast Earthquakes,” explains how USGS scientists are researching factors that influence regional differences in the intensity and effects of earthquakes, and notes that earthquakes in the East are often felt at more than twice the distance of earthquakes in the West.

Predicting when they will occur is more difficult, said Thomas Pratt, a research geophysicist and the central and Eastern U.S. coordinator for the USGS Earthquake Hazards Program in Reston, Va.

“One of the problems in the East Coast is that we don’t have a history to study,” he said. “In order to get an idea, we have to have had several cycles of these things. The way we know about them in California is we dig around in the mud and we see evidence of past earthquakes.”

Yet Pratt wouldn’t rule out the possibility of a high-magnitude event taking place in New York, which sits in the middle the North American Tectonic Plate, considered by experts to be quite stable.

“We never know,” he said. “One could come tomorrow. On the other hand, it could be another 300 years. We don’t understand why earthquakes happen (here) at all.”

Though the city’s last observable earthquake occurred on Oct. 27, 2001, and caused no real damage, New York has been hit by two Magnitude 5 earthquakes in its history – in 1738 and in 1884 — prompting many to say it is “due” for another.

While earthquakes generally have to be Magnitude 6 or higher to be considered “large,” by experts, “a Magnitude 5, directly under New York City, would shake it quite strongly,” Pratt said.

The reason has to do with the rock beneath our feet, the USGS report says.

OLDER ROCKS

In the East, we have older rocks, some of which formed “hundreds of millions of years before those in the West,” the report says. Since the faults in the rocks have had so much time to heal, the seismic waves travel more efficiently through them when an earthquake occurs.

“Rocks in the East are like a granite countertop and rocks in the West are much softer,” Pratt said. “Take a granite countertop and hit it and it’ll transmit energy well. In the West, it’s like a sponge. The energy gets absorbed.”

If a large, Magnitude 7 earthquake does occur, smaller structures, and older structures in Manhattan would be most vulnerable, Pratt said. “In the 1920s, ’30s and late 1800s, they were not built with earthquake resistance,” he said, noting that newer skyscrapers were built to survive hurricanes, so would be more resistant.

When discussing earthquake prediction and probability, Pratt uses the analogy of a baseball player who averages a home run every 10 times at bat and hasn’t hit one in the past nine games: “When he’s up at bat, will he hit a home run? You just don’t know.”

And though it would probably take a magnitude of 7 to topple buildings in the city, smaller earthquakes are still quite dangerous, he said.

“Bookshelves could fall down and hit you,” he said. “People could be killed.” A lot of stone work and heavy objects fell from buildings when a quake of 5.8 magnitude struck central Virginia in 2011, he noted, but, fortunately, no one was injured.

To be safe, Pratt encourages New Yorkers to keep a few days’ worth of drinking water and other supplies on hand. He, himself, avoids putting heavy things up high.

“It always gets me nervous when I go into a restaurant that has heavy objects high on shelves,” he said. “It’s unlikely you’ll get an earthquake. But, we just don’t know

A Closer Look At the Sixth Seal (Revelation 6:12)

img_2674LOOK AT NEW YORK CITY’S EARTHQUAKE RISKS

By Spectrum News NY1 | April 2, 2018 @4:32 PM

Not every New Yorker felt when the ground shook on August 23, 2011.

When a magnitude 5.8 earthquake cracked the soil near Mineral, Virginia that day, the energy traveled through the Northeast.

Some New Yorkers watched their homes tremor, while others felt nothing.

Researchers say New York City is due for a significant earthquake originating near the five boroughs, based on previous smaller earthquakes in and around the city. While New York is at moderate risk for earthquakes, its high population and infrastructure could lead to significant damage when a magnitude 5 quake or stronger hits the area.

Unbeknownst to many, there are numerous fault lines in the city, but a few stand out for their size and prominence: the 125th Street Fault, the Dyckman Street Fault, the Mosholu Parkway Fault, and the East River Fault.

The 125th Street Fault is the largest, running along the street, extending from New Jersey to the East River. Part of it runs to the northern tip of Central Park, while a portion extends into Roosevelt Island.

The Dyckman Street Fault is located in Inwood, crossing the Harlem River and into Morris Heights, while the Mosholu Parkway Fault is north of the Dyckman Street and 125th Street Faults.

The East River Fault looks a bit like an obtuse angle, with its top portion running parallel, to the west of Central Park, before taking a horizontal turn near 32nd St. and extending into the East River and stopping short of Brooklyn.

Just outside of the city is the Dobbs Ferry Fault, located in suburban Westchester; and the Ramapo Fault, running from eastern Pennsylvania to the mid-Hudson Valley, passing within a few miles northwest of the Indian Point Nuclear Plant, less than 40 miles north of the city and astride the intersection of two active seismic zones.

The locations of faults and the prevalence of earthquakes is generally not a concern for most New Yorkers. One reason might be that perceptions of weaker earthquakes vary widely.

On Nov. 30, a magnitude 4.1 earthquake, centered near Dover, Delaware, could be felt in nearby states. Less than 200 miles away in New York City, some people reported on social media that they felt their houses and apartments shaking. At the same time, some New Yorkers, again, did not feel anything:

Won-Young Kim is a senior research scientist at Columbia University’s Lamont-Doherty Earth Observatory, which monitors and records data on earthquakes that occur in the northeast. Kim says it’s not clear who feels smaller earthquakes, as evident by a magnitude 0.8 quake in the city in December of 2004.

“Hundreds of people called local police, and police called us. Our system was unable to detect that tiny earthquake automatically,” Kim said. “We looked at it, and, indeed, there was a small signal.”

Kim says some parts of the city will feel magnitude 1 or 2 earthquakes even if the seismic activity does not result in any damage.

You have to go back to before the 20th Century, however, to find the last significant earthquake that hit the city. According to Lamont-Doherty researchers, magnitude 5.2 earthquakes occurred in 1737 and 1884. In newspaper accounts, New Yorkers described chimneys falling down and feeling the ground shake underneath them.

“1737 — that was located close to Manhattan,” Kim said. “It was very close to New York City.”

According to Kim, the 1884 quake was felt in areas in or close to the city, such as the Rockaways and Sandy Hook, New Jersey. But it was felt even as far away as Virginia and Maine.

From 1677 to 2007, there were 383 known earthquakes in a 15,000-square-mile area around New York City, researchers at Lamont-Doherty said in a 2008 study.

A 4.9 located in North Central New Jersey was felt in the city in 1783; a 4 hit Ardsley in 1985; and in 2001, magnitude 2.4 and 2.6 quakes were detected in Manhattan itself for the first time.

But the 1737 and 1884 quakes remain the only known ones of at least magnitude 5 to hit the city.

Smaller earthquakes are not to be ignored. Lamont-Doherty researchers say frequent small quakes occur in predictable ratios to larger ones and thus can be used — along with the fault lengths, detected tremors and calculations of how stress builds in the crust — to create a rough time scale.

The takeaway? New York City is due for a significant earthquake.

Researchers say New York City is susceptible to at least a magnitude 5 earthquake once every 100 years, a 6 about every 670 years, and 7 about every 3,400 years.

It’s been 134 years since New York was last hit by at least a magnitude 5. When it happens next, researchers say it won’t be much like 1884.

The city’s earthquake hazard is moderate, according to the New York City Area Consortium for Earthquake Loss Mitigation (NYCEM), but experts agree that, due to its higher population and infrastructure, the damage would be significant.

Before 1995, earthquake risks were not taken into consideration for the city’s building code. Thus, Lamont-Doherty says many older buildings, such as unenforced three- to six-story buildings, could suffer major damage or crumble.

The damage an earthquake causes is also dependent on what’s in the ground. According to the U.S. Geological Survey, bedrock is more resistant to earthquakes than sediment.

The upper third of Manhattan has harder soil that is more resistant to shaking. Parts of Midtown are more susceptible, while Downtown Manhattan’s soil is even softer, according to the NYCEM.

Exceptions to Upper Manhattan’s strength? Portions of Harlem and Inwood — both areas consist of a large amount of soft soil. Central Park has the strongest soil in Manhattan, outside of a small segment of Inwood..

Not all boroughs are created equal. While the Bronx is also made of solid bedrock, the ground in Queens and Brooklyn is softer.

“If you go to Queens and Brooklyn, you have sediment, so there would be more shaking relative to Manhattan,” Kim said. “So, it’s not easy to say the damage would be the same.”

Analysis pins the damage from a magnitude 5 earthquake hitting New York City in the billions, according to Lamont-Doherty.

New York City is not a hotbed for seismic activity; it is not close to a tectonic plate, and it is not clear if one of the faults would be the source of a strong quake. But the predicted damage to the city has concerned many experts.

Until that day, earthquakes are isolated events for New Yorkers. Some have felt the ground move, while others have only felt shaking when subway cars travel underground.

But researchers agree: One day, the ground will wake up in the city that never sleeps, and all New Yorkers will understand what Mineral, Virginia felt when their homes rattled with the earth.