On the Road to America’s Next Devastating Earthquake in NYC: Revelation 6

             

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

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

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.

The Sixth Seal Long Overdue (Revelation 6)

  

       

ON THE MAP; Exploring the Fault Where the Next Big One May Be Waiting

The Big One Awaits

By MARGO NASH

Published: March 25, 2001

Alexander Gates, a geology professor at Rutgers-Newark, is co-author of “The Encyclopedia of Earthquakes and Volcanoes,“ which will be published by Facts on File in July. He has been leading a four-year effort to remap an area known as the Sloatsburg Quadrangle, a 5-by-7-mile tract near Mahwah that crosses into New York State. The Ramapo Fault, which runs through it, was responsible for a big earthquake in 1884, and Dr. Gates warns that a recurrence is overdue. He recently talked about his findings.

Q. What have you found?

A. We’re basically looking at a lot more rock, and we’re looking at the fracturing and jointing in the bedrock and putting it on the maps. Any break in the rock is a fracture. If it has movement, then it’s a fault. There are a lot of faults that are offshoots of the Ramapo. Basically when there are faults, it means you had an earthquake that made it. So there was a lot of earthquake activity to produce these features. We are basically not in a period of earthquake activity along the Ramapo Fault now, but we can see that about six or seven times in history, about 250 million years ago, it had major earthquake activity. And because it’s such a fundamental zone of weakness, anytime anything happens, the Ramapo Fault goes.

Q. Where is the Ramapo Fault?

 A. The fault line is in western New Jersey and goes through a good chunk of the state, all the way down to Flemington. It goes right along where they put in the new 287. It continues northeast across the Hudson River right under the Indian Point power plant up into Westchester County. There are a lot of earthquakes rumbling around it every year, but not a big one for a while.

Q. Did you find anything that surprised you?

A. I found a lot of faults, splays that offshoot from the Ramapo that go 5 to 10 miles away from the fault. I have looked at the Ramapo Fault in other places too. I have seen splays 5 to 10 miles up into the Hudson Highlands. And you can see them right along the roadsides on 287. There’s been a lot of damage to those rocks, and obviously it was produced by fault activities. All of these faults have earthquake potential.

Q. Describe the 1884 earthquake.

A. It was in the northern part of the state near the Sloatsburg area. They didn’t have precise ways of describing the location then. There was lots of damage. Chimneys toppled over. But in 1884, it was a farming community, and there were not many people to be injured. Nobody appears to have written an account of the numbers who were injured.

Q. What lessons we can learn from previous earthquakes?

A. In 1960, the city of Agadir in Morocco had a 6.2 earthquake that killed 12,000 people, a third of the population, and injured a third more. I think it was because the city was unprepared.There had been an earthquake in the area 200 years before. But people discounted the possibility of a recurrence. Here in New Jersey, we should not make the same mistake. We should not forget that we had a 5.4 earthquake 117 years ago. The recurrence interval for an earthquake of that magnitude is every 50 years, and we are overdue. The Agadir was a 6.2, and a 5.4 to a 6.2 isn’t that big a jump.

Q. What are the dangers of a quake that size?

A. When you’re in a flat area in a wooden house it’s obviously not as dangerous, although it could cut off a gas line that could explode. There’s a real problem with infrastructure that is crumbling, like the bridges with crumbling cement. There’s a real danger we could wind up with our water supplies and electricity cut off if a sizable earthquake goes off. The best thing is to have regular upkeep and keep up new building codes. The new buildings will be O.K. But there is a sense of complacency.

MARGO NASH

New York Subways at the Sixth Seal (Revelation 6)

                     How vulnerable are NYC’s underwater subway tunnels to flooding?

Ashley Fetters
New York City is full of peculiar phenomena—rickety fire escapes; 100-year-old subway tunnels; air conditioners propped perilously into window frames—that can strike fear into the heart of even the toughest city denizen

ew York-specific fears, letting you know what you should actually worry about, and what anxieties you can simply let slip away.
The 25-minute subway commute from Crown Heights to the Financial District on the 2/3 line is, in my experience, a surprisingly peaceful start to the workday—save for one 3,100-foot stretch between the Clark Street and Wall Street stations, where for three minutes I sit wondering what the probability is that I will soon die a torturous, claustrophobic drowning death right here in this subway car.
The Clark Street Tunnel, opened in 1916, is one of approximately a dozen tunnels that escort MTA passengers from one borough to the next underwater—and just about all of them, with the exception of the 1989 addition of the 63rd Street F train tunnel, were constructed between 1900 and 1936.
Each day, thousands of New Yorkers venture across the East River and back again through these tubes buried deep in the riverbed, some of which are nearing or even past their 100th birthdays. Are they wrong to ponder their own mortality while picturing one of these watery catacombs suddenly springing a leak?
Mostly yes, they are, says Michael Horodniceanu, the former president of MTA Capital Construction and current principal of Urban Advisory Group. First, it’s important to remember that the subway tunnel is built under the riverbed, not just in the river—so what immediately surrounds the tunnel isn’t water but some 25 feet of soil. “There’s a lot of dirt on top of it,” Horodniceanu says. “It’s well into the bed of the bottom of the channel.”
And second, as Angus Kress Gillespie, author of Crossing Under the Hudson: The Story of the Holland and Lincoln Tunnels, points out, New York’s underwater subway tunnels are designed to withstand some leaking. And withstand it they do: Pumps placed below the floor of the tunnel, he says, are always running, always diverting water seepage into the sewers. (Horodniceanu says the amount of water these pumps divert into the sewer system each day numbers in the thousands of gallons.)
Additionally, MTA crews routinely repair the grouting and caulking, and often inject a substance into the walls that creates a waterproof membrane outside the tunnel—which keeps water out of the tunnel and relieves any water pressure acting on its walls. New tunnels, Horodniceanu points out, are even built with an outside waterproofing membrane that works like an umbrella: Water goes around it, it falls to the sides, and then it gets channeled into a pumping station and pumped out.
Of course, the classic New York nightmare scenario isn’t just a cute little trickle finding its way in. The anxiety daydream usually involves something sinister, or seismic. The good news, however, is that while an earthquake or explosion would indeed be bad for many reasons, it likely wouldn’t result in the frantic flooding horror scene that plays out in some commuters’ imaginations.
The Montague Tube, which sustained severe damage during Hurricane Sandy.
MTA New York City Transit / Marc A. Hermann
Horodniceanu assures me that tunnels built more recently are “built to withstand a seismic event.” The older tunnels, however—like, um, the Clark Street Tunnel—“were not seismically retrofitted, let me put it that way,” Horodniceanu says. “But the way they were built is in such a way that I do not believe an earthquake would affect them.” They aren’t deep enough in the ground, anyway, he says, to be too intensely affected by a seismic event. (The MTA did not respond to a request for comment.)
One of the only real threats to tunnel infrastructure, Horodniceanu adds, is extreme weather. Hurricane Sandy, for example, caused flooding in the tunnels, which “created problems with the infrastructure.” He continues, “The tunnels have to be rebuilt as a result of saltwater corroding the infrastructure.”
Still, he points out, hurricanes don’t exactly happen with no warning. So while Hurricane Sandy did cause major trauma to the tunnels, train traffic could be stopped with ample time to keep passengers out of harm’s way. In 2012, Governor Andrew Cuomo directed all the MTA’s mass transit services to shut down at 7 p.m. the night before Hurricane Sandy was expected to hit New York City.
And Gillespie, for his part, doubts even an explosion would result in sudden, dangerous flooding. A subway tunnel is not a closed system, he points out; it’s like a pipe that’s open at both ends. “The force of a blast would go forwards and backwards out the exit,” he says.
So the subway-train version of that terrifying Holland Tunnel flood scene in Sylvester Stallone’s Daylight is … unrealistic, right?
“Yeah,” Gillespie laughs. “Yeah. It is.”
Got a weird New York anxiety that you want explored? E-mail tips@curbed.com, and we may include it in a future column.

USA’s Fukushima At The Sixth Seal in New York (Revelation 6)

Recent series of Indian Point shutdowns worst in years

Ernie Garcia, elgarcia@lohud.com

BUCHANAN — Four unplanned reactor shutdowns over a two-month period at Indian Point are the most setbacks the nuclear power plant has experienced in years.

A review of unplanned shutdowns from January 2012 to the present showed this year’s events happened within a short time frame, between May 7 and July 8, in contrast with events from other years that were more spread out, according to data released by Indian Point.

So many mishaps at the Entergy-owned plant haven’t occurred since 2009, when one of two units at the Buchanan site experienced a similar series, said plant spokesman Jerry Nappi.

Besides a May 9 transformer failure that spilled some 3,000 gallons of oil into  the Hudson River, this year’s shutdowns were prompted by a May 7 steam leak, a July 8 pump motor failure and a June 15 switch yard breaker failure offsite in a Consolidated Edison substation.

If a nuclear plant has more than three unplanned shutdowns in a nine-month period, its performance indicator could be changed by the federal Nuclear Regulatory Commission, which results in additional oversight. That’s what happened with Entergy’s Pilgrim Nuclear Power Station in Plymouth, Mass., after four unplanned shutdowns in 2013.

So far, Entergy said there doesn’t appear to be a pattern to the Indian Point shutdowns.

“You do want to look at these events holistically to see if there is something in common, but you also look individually to see what the causes were,” Nappi said. “A plant shutdown in and of itself is not a safety issue.”

One of the four recent Buchanan shutdowns triggered a special inspection by the NRC and calls to close the nuclear plant by environmental groups and elected officials. Gov. Andrew Cuomo has said in the past Indian Point should close, but his office did not respond to a request for comment about whether the recent shutdowns have prompted any state scrutiny.

The NRC is expected to release a quarterly report on Indian Point this month that will address the transformer failure and, by year’s end, is planning an inspection of the transformer and an analysis of transformer issues since 2007.

Besides its transformer-related inquiries, the other three shutdowns have not raised “any immediate safety concerns or crossed any thresholds that would result in additional NRC oversight,” agency spokesman Neil Sheehan wrote in an email.

The unplanned shutdowns at Indian Point and Pilgrim in Massachusetts were  mostly preventable, said Paul Blanch, a former Indian Point employee with 45 years of nuclear power experience.

“For this to happen this frequently indicates a deeper problem,” he said. “I believe it’s management oversight in the maintenance of these plants.”

Nappi said the transformer that failed May 9 and caused a fire and oil spill into the Hudson was regularly monitored. Investigators determined the failure was due to faulty insulation.

“The transformer inspection and reviews were in accordance with our standards and industry expectations, yet there was no indication the transformer was going to fail,” Nappi said.

The NRC conducted a separate, but related special inspection into the May 9 incident that focused on a half-inch of water that collected in an electrical switchgear room floor. Inspectors determined a fire suppression system’s valve failed to close properly.

Inspectors noted in their report that Entergy knew about that problem since April 2011 and replaced the valve but didn’t discover the actual cause — a dysfunctional switch — until after the fire.

Indian Point’s Unit 3 was down 19 days May through July, with the transformer failure accounting for 16 days. The shutdowns didn’t cause the public any supply problems because New York’s grid can import electricity from other states and New York has an energy plan to maintain reliability, according to the U.S. Energy Information Administration.

The nuclear energy industry judges a power plant on how continuously it produces energy, which is called a capacity factor.

There were 100 nuclear plants in the United States in 2014, a record year in terms of efficiency. In January, the Nuclear Energy Institute announced the U.S. average capacity factor was 91.9 percent.

Indian Point has an above-average efficiency rate. The plant’s Unit 2 and 3 reactors were each online more than 99 percent of the time during their most recent two-year operating cycles. They are currently in the middle of other cycles.

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)

The Year of the Sixth Seal in NYC 2026 (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

USGS Evidence Shows Power of the Sixth Seal in NYC (Revelation 6:12)

          

New Evidence Shows Power of East Coast Earthquakes
Virginia Earthquake Triggered Landslides at Great Distances

Released: 11/6/2012 8:30:00 AM USGS.gov

Earthquake shaking in the eastern United States can travel much farther and cause damage over larger areas than previously thought.

U.S. Geological Survey scientists found that last year’s magnitude 5.8 earthquake in Virginia triggered landslides at distances four times farther—and over an area 20 times larger—than previous research has shown.

“We used landslides as an example and direct physical evidence to see how far-reaching shaking from east coast earthquakes could be,” said Randall Jibson, USGS scientist and lead author of this study. “Not every earthquake will trigger landslides, but we can use landslide distributions to estimate characteristics of earthquake energy and how far regional ground shaking could occur.”

“Scientists are confirming with empirical data what more than 50 million people in the eastern U.S. experienced firsthand: this was one powerful earthquake,” said USGS Director Marcia McNutt. “Calibrating the distance over which landslides occur may also help us reach back into the geologic record to look for evidence of past history of major earthquakes from the Virginia seismic zone.”

This study will help inform earthquake hazard and risk assessments as well as emergency preparedness, whether for landslides or other earthquake effects.

This study also supports existing research showing that although earthquakes  are less frequent in the East, their damaging effects can extend over a much larger area as compared to the western United States.

The research is being presented today at the Geological Society of America conference, and will be published in the December 2012 issue of the Bulletin of the Seismological Society of America.

The USGS found that the farthest landslide from the 2011 Virginia earthquake was 245 km (150 miles) from the epicenter. This is by far the greatest landslide distance recorded from any other earthquake of similar magnitude. Previous studies of worldwide earthquakes indicated that landslides occurred no farther than 60 km (36 miles) from the epicenter of a magnitude 5.8 earthquake.

“What makes this new study so unique is that it provides direct observational evidence from the largest earthquake to occur in more than 100 years in the eastern U.S,” said Jibson. “Now that we know more about the power of East Coast earthquakes, equations that predict ground shaking might need to be revised.”

It is estimated that approximately one-third of the U.S. population could have felt last year’s earthquake in Virginia, more than any earthquake in U.S. history. About 148,000 people reported their ground-shaking experiences caused by the earthquake on the USGS “Did You Feel It?” website. Shaking reports came from southeastern Canada to Florida and as far west as Texas.

In addition to the great landslide distances recorded, the landslides from the 2011 Virginia earthquake occurred in an area 20 times larger than expected from studies of worldwide earthquakes. Scientists plotted the landslide locations that were farthest out and then calculated the area enclosed by those landslides. The observed landslides from last year’s Virginia earthquake enclose an area of about 33,400 km2, while previous studies indicated an expected area of about 1,500 km2from an earthquake of similar magnitude.

“The landslide distances from last year’s Virginia earthquake are remarkable compared to historical landslides across the world and represent the largest distance limit ever recorded,” said Edwin Harp, USGS scientist and co-author of this study. “There are limitations to our research, but the bottom line is that we now have a better understanding of the power of East Coast earthquakes and potential damage scenarios.”

The difference between seismic shaking in the East versus the West is due in part to the geologic structure and rock properties that allow seismic waves to travel farther without weakening.

Learn more about the 2011 central Virginia earthquake.