New York City isn’t immune to earthquakes; a couple of small tremors measuring about 2.5 on the Richter scale even struck back in 2001 and 2002.But on August 10, 1884, a more powerful earthquake hit. Estimated from 4.9 to 5.5 in magnitude, the tremor made houses shake, chimneys fall, and residents wonder what the heck was going on, according to a New York Timesarticle two days later.The quake was subsequently thought to have been centered off Far Rockaway or Coney Island.It wasn’t the first moderate quake, and it won’t be the last. In a 2008 Columbia University study, seismologists reported that the city is crisscrossed with several fault lines, one along 125th Street. With that in mind, New Yorkers should expect a 5.0 or higher earthquake centered here every 100 years, the seismologists say.Translation: We’re about 30 years overdue. Lucky for us the city adopted earthquake-resistant building codes in 1995.1884 A Forewarning Of The Sixth Seal (Revelation 6:12)
Did you feel it? At 9:10 am EST Sunday morning, a Magnitude 3.6 earthquake struck just south of Bliss Corner, Massachusetts, which is a census-designated place in Dartmouth. If you felt it, report it!
While minor earthquakes do happen from time to time in New England, tremors that are felt by a large number of people and that cause damage are rare.
The earthquake was originally measured as a magnitude 4.2 on the Richter scale by the United States Geological Surgey (USGS) before changing to a 3.6.
Earthquakes in New England and most places east of the Rocky Mountains are much different than the ones that occur along well-known fault lines in California and along the West Coast.
Rhode Island and Southeastern Massachusetts fall nearly in the center of the North American Plate, one of 15 (seven primary, eight secondary) that cover the Earth.
Earth’s tectonic plates
Tectonic plates move ever-so-slowly, and as they either push into each other, pull apart, or slide side-by-side, earthquakes are possible within the bedrock, usually miles deep.
Most of New England’s and Long Island’s bedrock was assembled as continents collided to form a supercontinent 500-300 million years ago, raising the northern Appalachian Mountains.
Plate tectonics (Courtesy: Encyclopaedia Britannica)
Fault lines left over from the creation of the Appalachian Mountains can still lead to earthquakes locally, and many faults remain undetected. According to the USGS, few, if any, earthquakes in New England can be linked to named faults.
While earthquakes in New England are generally much weaker compared to those on defined fault lines, their reach is still impressive. Sunday’s 3.6 was felt in Rhode Island, Massachusetts, Connecticut, New York, and New Hampshire.
USGS Community Internet Intensity Map
While M 3.6 earthquakes rarely cause damage, some minor cracks were reported on social media from the shaking.
According to the USGS, moderately damaging earthquakes strike somewhere in the region every few decades, and smaller earthquakes are felt roughly twice a year.
The most recent New England earthquake to cause moderate damage occurred in 1940 (magnitude 5.6) in central New Hampshire.
By WILLIAM K. STEVENSPublished: 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.
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.”
East Coast Earthquake Preparedness
By By BEN NUCKOLS
Posted: 08/25/2011 8:43 am EDT
WASHINGTON — There were cracks in the Washington Monument and broken capstones at the National Cathedral. In the District of Columbia suburbs, some people stayed in shelters because of structural concerns at their apartment buildings.
A day after the East Coast’s strongest earthquake in 67 years, inspectors assessed the damage and found that most problems were minor. But the shaking raised questions about whether this part of the country, with its older architecture and inexperience with seismic activity, is prepared for a truly powerful quake.
The 5.8 magnitude quake felt from Georgia north to Canada prompted swift inspections of many structures Wednesday, including bridges and nuclear plants. An accurate damage estimate could take weeks, if not longer. And many people will not be covered by insurance.
In a small Virginia city near the epicenter, the entire downtown business district was closed. School was canceled for two weeks to give engineers time to check out cracks in several buildings.
At the 555-foot Washington Monument, inspectors found several cracks in the pyramidion – the section at the top of the obelisk where it begins narrowing to a point.
A 4-foot crack was discovered Tuesday during a visual inspection by helicopter. It cannot be seen from the ground. Late Wednesday, the National Park Service announced that structural engineers had found several additional cracks inside the top of the monument.
Carol Johnson, a park service spokeswoman, could not say how many cracks were found but said three or four of them were “significant.” Two structural engineering firms that specialize in assessing earthquake damage were being brought in to conduct a more thorough inspection on Thursday.
The monument, by far the tallest structure in the nation’s capital, was to remain closed indefinitely, and Johnson said the additional cracks mean repairs are likely to take longer. It has never been damaged by a natural disaster, including earthquakes in Virginia in 1897 and New York in 1944.
Tourists arrived at the monument Wednesday morning only to find out they couldn’t get near it. A temporary fence was erected in a wide circle about 120 feet from the flags that surround its base. Walkways were blocked by metal barriers manned by security guards.
“Is it really closed?” a man asked the clerk at the site’s bookstore.
“It’s really closed,” said the clerk, Erin Nolan. Advance tickets were available for purchase, but she cautioned against buying them because it’s not clear when the monument will open.
“This is pretty much all I’m going to be doing today,” Nolan said.
Tuesday’s quake was centered about 40 miles northwest of Richmond, 90 miles south of Washington and 3.7 miles underground. In the nearby town of Mineral, Va., Michael Leman knew his Main Street Plumbing & Electrical Supply business would need – at best – serious and expensive repairs.
At worst, it could be condemned. The facade had become detached from the rest of the building, and daylight was visible through a 4- to 6-inch gap that opened between the front wall and ceiling.
“We’re definitely going to open back up,” Leman said. “I’ve got people’s jobs to look out for.”
Leman said he is insured, but some property owners might not be so lucky.
The Insurance Information Institute said earthquakes are not covered under standard U.S. homeowners or business insurance policies, although supplemental coverage is usually available.
The institute says coverage for other damage that may result from earthquakes, such as fire and water damage from burst gas or water pipes, is provided by standard homeowners and business insurance policies in most states. Cars and other vehicles with comprehensive insurance would also be protected.
The U.S. Geological Survey classified the quake as Alert Level Orange, the second-most serious category on its four-level scale. Earthquakes in that range lead to estimated losses between $100 million and $1 billion.
In Culpeper, Va., about 35 miles from the epicenter, walls had buckled at the old sanctuary at St. Stephen’s Episcopal Church, which was constructed in 1821 and drew worshippers including Confederate Gens. Robert E. Lee and J.E.B. Stuart. Heavy stone ornaments atop a pillar at the gate were shaken to the ground. A chimney from the old Culpeper Baptist Church built in 1894 also tumbled down.
At the Washington National Cathedral, spokesman Richard Weinberg said the building’s overall structure remains sound and damage was limited to “decorative elements.”
Massive stones atop three of the four spires on the building’s central tower broke off, crashing onto the roof. At least one of the spires is teetering badly, and cracks have appeared in some flying buttresses.
Repairs were expected to cost millions of dollars – an expense not covered by insurance.
“Every single portion of the exterior is carved by hand, so everything broken off is a piece of art,” Weinberg said. “It’s not just the labor, but the artistry of replicating what was once there.”
The building will remain closed as a precaution. Services to dedicate the memorial honoring Rev. Martin Luther King Jr. were moved.
Other major cities along the East Coast that felt the shaking tried to gauge the risk from another quake.
A few hours after briefly evacuating New York City Hall, Mayor Michael Bloomberg said the city’s newer buildings could withstand a more serious earthquake. But, he added, questions remain about the older buildings that are common in a metropolis founded hundreds of years ago.
“We think that the design standards of today are sufficient against any eventuality,” he said. But “there are questions always about some very old buildings. … Fortunately those tend to be low buildings, so there’s not great danger.”
An earthquake similar to the one in Virginia could do billions of dollars of damage if it were centered in New York, said Barbara Nadel, an architect who specializes in securing buildings against natural disasters and terrorism.
The city’s 49-page seismic code requires builders to prepare for significant shifting of the earth. High-rises must be built with certain kinds of bracing, and they must be able to safely sway at least somewhat to accommodate for wind and even shaking from the ground, Nadel said.
Buildings constructed in Boston in recent decades had to follow stringent codes comparable to anything in California, said Vernon Woodworth, an architect and faculty member at the Boston Architectural College. New construction on older structures also must meet tough standards to withstand severe tremors, he said.
It’s a different story with the city’s older buildings. The 18th- and 19th-century structures in Boston’s Back Bay, for instance, were often built on fill, which can liquefy in a strong quake, Woodworth said. Still, there just aren’t many strong quakes in New England.
The last time the Boston area saw a quake as powerful as the one that hit Virginia on Tuesday was in 1755, off Cape Ann, to the north. A repeat of that quake would likely cause deaths, Woodworth said. Still, the quakes are so infrequent that it’s difficult to weigh the risks versus the costs of enacting tougher building standards regionally, he said.
People in several of the affected states won’t have much time to reflect before confronting another potential emergency. Hurricane Irene is approaching the East Coast and could skirt the Mid-Atlantic region by the weekend and make landfall in New England after that.
In North Carolina, officials were inspecting an aging bridge that is a vital evacuation route for people escaping the coastal barrier islands as the storm approaches.
Speaking at an earthquake briefing Wednesday, Washington Mayor Vincent Gray inadvertently mixed up his disasters.
“Everyone knows, obviously, that we had a hurricane,” he said before realizing his mistake.
“Hurricane,” he repeated sheepishly as reporters and staffers burst into laughter. “I’m getting ahead of myself!”
Associated Press writers Sam Hananel in Washington; Alex Dominguez in Baltimore; Bob Lewis in Mineral, Va.; Samantha Gross in New York City; and Jay Lindsay in Boston contributed to this report.
January 20, 2010New York City isn’t immune to earthquakes; a couple of small tremors measuring about 2.5 on the Richter scale even struck back in 2001 and 2002.But on August 10, 1884, a more powerful earthquake hit. Estimated from 4.9 to 5.5 in magnitude, the tremor made houses shake, chimneys fall, and residents wonder what the heck was going on, according to a New York Timesarticle two days later.The quake was subsequently thought to have been centered off Far Rockaway or Coney Island.It wasn’t the first moderate quake, and it won’t be the last. In a 2008 Columbia University study, seismologists reported that the city is crisscrossed with several fault lines, one along 125th Street. With that in mind, New Yorkers should expect a 5.0 or higher earthquake centered here every 100 years, the seismologists say.Translation: We’re about 30 years overdue. Lucky for us the city adopted earthquake-resistant building codes in 1995.1884 A Forewarning Of The Sixth Seal (Revelation 6:12)
A Look at the Tri-State’s Active Fault LineMonday, March 14, 2011By Bob Hennelly
The Ramapo Fault is the longest fault in the Northeast that occasionally makes local headlines when minor tremors cause rock the Tri-State region. It begins in Pennsylvania, crosses the Delaware River and continues through Hunterdon, Somerset, Morris, Passaic and Bergen counties before crossing the Hudson River near Indian Point nuclear facility.In the past, it has generated occasional activity that generated a 2.6 magnitude quake in New Jersey’s Peakpack/Gladstone area and 3.0 magnitude quake in Mendham.But the New Jersey-New York region is relatively seismically stable according to Dr. Dave Robinson, Professor of Geography at Rutgers. Although it does have activity.„There is occasional seismic activity in New Jersey,“ said Robinson. „There have been a few quakes locally that have been felt and done a little bit of damage over the time since colonial settlement — some chimneys knocked down in Manhattan with a quake back in the 18th century, but nothing of a significant magnitude.“Robinson said the Ramapo has on occasion registered a measurable quake but has not caused damage: „The Ramapo fault is associated with geological activities back 200 million years ago, but it’s still a little creaky now and again,“ he said.„More recently, in the 1970s and early 1980s, earthquake risk along the Ramapo Fault received attention because of its proximity to Indian Point,“ according to the New Jersey Geological Survey website.Historically, critics of the Indian Point Nuclear facility in Westchester County, New York, did cite its proximity to the Ramapo fault line as a significant risk.In 1884, according to the New Jersey Geological Survey website, the Rampao Fault was blamed for a 5.5 quake that toppled chimneys in New York City and New Jersey that was felt from Maine to Virginia.„Subsequent investigations have shown the 1884 Earthquake epicenter was actually located in Brooklyn, New York, at least 25 miles from the Ramapo Fault,“ according to the New Jersey Geological Survey website.
On Nov. 8, a 3.6 magnitude earthquake struck Buzzard’s Bay off the coast of New Bedford. Reverberations were felt up to 100 miles away, across Massachusetts, Rhode Island, and parts of Connecticut and New York. News outlets scrambled to interview local residents who felt the ground shake their homes. Seismologists explained that New England earthquakes, while uncommon and usually minor, are by no means unheard of.
It’s sometimes called the Boston Earthquake and sometimes the Cape Ann Earthquake. Its epicenter is thought to have been in the Atlantic Ocean about 25 miles east of Gloucester. Estimates say that it would have registered between 6.0 and 6.3 on the modern Richter scale. It was an occasion to remember as chronicled by John E. Ebel, director of the Weston observatory of Boston College:
“At about 4:30 in the morning on 18 November, 1755, a strong earthquake rocked the New England area. Observers reported damage to chimneys, brick buildings and stone walls in coastal communities from Portland, Maine to south of Boston … Chimneys were also damaged as far away as Springfield, Massachusetts, and New Haven, Connecticut. The earthquake was felt at Halifax, Nova Scotia to the northeast, Lake Champlain to the northwest, and Winyah, South Carolina to the southwest. The crew of a ship in deep water about 70 leagues east of Boston thought it had run aground and only realized it had felt an earthquake after it arrived at Boston later that same day.
“The 1755 earthquake rocked Boston, with the shaking lasting more than a minute. According to contemporary reports, as many as 1,500 chimneys were shattered or thrown down in part, the gable ends of about 15 brick buildings were broken out, and some church steeples ended up tilted due to the shaking. Falling chimney bricks created holes in the roofs of some houses. Some streets, particularly those on manmade ground along the water, were so covered with bricks and debris that passage by horse-drawn carriage was impossible. Many homes lost china and glassware that was thrown from shelves and shattered. A distiller’s cistern filled with liquor broke apart and lost its contents.”
We don’t have many details of the earthquake’s impact here, there being no newspaper in Worcester County at that time. We do know that one man, Christian Angel, working in a “silver” mine in Sterling, was buried alive when the ground shook. He is the only known fatality in these parts. We can assume that, if the quake shook down chimneys in Springfield and New Haven, it did even more damage hereabouts. We can imagine the cries of alarm and the feeling of panic as trees swayed violently, fields and meadows trembled underfoot and pottery fell off shelves and crashed below.
The Boston Earthquake was an aftershock from the gigantic Lisbon Earthquake that had leveled Lisbon, Portugal, a few days before. That cataclysm, estimated as an 8 or 9 on the modern Richter scale, was the most devastating natural catastrophe to hit western Europe since Roman times. The first shock struck on Nov. 1, at about 9 in the morning.
According to one account: ”Suddenly the city began to shudder violently, its tall medieval spires waving like a cornfield in the breeze … In the ancient cathedral, the Basilica de Santa Maria, the nave rocked and the massive chandeliers began swinging crazily. . . . Then came a second, even more powerful shock. And with it, the ornate façade of every great building in the square … broke away and cascaded forward.”
Until that moment, Lisbon had been one of the leading cities in western Europe, right up there with London and Paris. With 250,000 people, it was a center of culture, financial activity and exploration. Within minutes it was reduced to smoky, dusty rubble punctuated by human groans and screams. An estimated 60,000 to 100,000 lost their lives.
Since then, New England has been mildly shaken by quakes from time to time. One series of tremors on March 1, 1925, was felt throughout Worcester County, from Fitchburg to Worcester, and caused a lot of speculation.
What if another quake like that in 1755 hit New England today? What would happen? That question was studied 15 years ago by the Massachusetts Civil Defense Agency. Its report is sobering:
“The occurrence of a Richter magnitude 6.25 earthquake off Cape Ann, Massachusetts … would cause damage in the range of 2 to 10 billion dollars … in the Boston metropolitan area (within Route 128) due to ground shaking, with significant additional losses due to secondary effects such as soil liquefaction failures, fires and economic interruptions. Hundreds of deaths and thousands of major and minor injuries would be expected … Thousands of people could be displaced from their homes … Additional damage may also be experienced outside the 128 area, especially closer to the earthquake epicenter.”
So even if we don’t worry much about volcanoes, we know that hurricanes and tornadoes are always possible. As for earthquakes, they may not happen in this century or even in this millennium, but it is sobering to think that if the tectonic plates under Boston and Gloucester shift again, we could see a repeat of 1755.
It was around 8 p.m. on Saturday, Feb. 16, that the 2.1 magnitude earthquake was recorded. It was a shake-up that took place in northeast Summerville, neighboring the Berkley and Dorchester county border, and largely went unnoticed by locals.
Generally earthquakes that are less than a magnitude 3.0 are not felt, explained Mario Formisano, Dorchester County Director of Emergency Management.
However, there have been approximately 50 reports of residents who said they felt its effects, according to the United States Geological Survey. Still, there remains no reports of injury or damage.
The very nature of earthquakes are completely unpredictable, which is why members of the Dorchester County Emergency Management Department have exercised earthquake preparedness scenarios multiple times throughout the past decade.
Formisano said that because of the counties positioning along the seismic zone, a mitigation plan has been put in place, identifying earthquakes as a major natural hazard for the area. This plan outlines mitigation strategies developed to reduce impacts in the case of a more severe quake.
Many new residents move to the area unaware of the local seismic zone. Formaisano pointed out that while some residents will opt to pick up an earthquake insurance policy, many gamble on avoiding experiencing a major earthquake in their lifetime.
Though records indicate that the last several earthquakes have registered at magnitudes low enough for there to be little to no impact, the area is not unaccustomed to facing a quake of larger volume.
With a magnitude of 7.3, the historical Charleston earthquake of 1886 led to economic losses of approximately $23 million dollars and at least 60 deaths all within the first moments of its impact, according to a report by the USGS.
Additionally, within 10 minutes, the effects of the quake were reported to have been experienced in places as far away as New York, Missouri and Illinois.
Over the next 30 years, the USGS reported that more than 400 aftershocks were felt in the surrounding Charleston area, contributing to additional wreckage.
“The risk has and will always exist for a major earthquake in our area,” Formaisano said. “That combined with the unpredictability of earthquakes is a reminder for residents and business to always be prepared.”
Quakeland: On the Road to America’s Next Devastating EarthquakeRoger BilhamGiven 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 History of Earthquakes In New YorkBy Meteorologist Michael Gouldrick New York State PUBLISHED 6:30 AM ET Sep. 09, 2020 PUBLISHED 6:30 AM EDT Sep. 09, 2020New York State has a long history of earthquakes. Since the early to mid 1700s there have been over 550 recorded earthquakes that have been centered within the state’s boundary. New York has also been shaken by strong earthquakes that occurred in southeast Canada and the Mid-Atlantic states.
Courtesy of Northeast States Emergency ConsortiumThe largest earthquake that occurred within New York’s borders happened on September 5th, 1944. It was a magnitude 5.9 and did major damage in the town of Massena.A school gymnasium suffered major damage, some 90% of chimneys toppled over and house foundations were cracked. Windows broke and plumbing was damaged. This earthquake was felt from Maine to Michigan to Maryland.Another strong quake occurred near Attica on August 12th, 1929. Chimneys took the biggest hit, foundations were also cracked and store shelves toppled their goods.In more recent memory some of the strongest quakes occurred On April 20th, 2002 when a 5.0 rattled the state and was centered on Au Sable Forks area near Plattsburg, NY.Strong earthquakes outside of New York’s boundary have also shaken the state. On February 5th, 1663 near Charlevoix, Quebec, an estimated magnitude of 7.5 occurred. A 6.2 tremor was reported in Western Quebec on November 1st in 1935. A 6.2 earthquake occurred in the same area on March 1st 1925. Many in the state also reported shaking on August 23rd, 2011 from a 5.9 earthquake near Mineral, Virginia.
Earthquakes in the northeast U.S. and southeast Canada are not as intense as those found in other parts of the world but can be felt over a much larger area. The reason for this is the makeup of the ground. In our part of the world, the ground is like a jigsaw puzzle that has been put together. If one piece shakes, the whole puzzle shakes.In the Western U.S., the ground is more like a puzzle that hasn’t been fully put together yet. One piece can shake violently, but only the the pieces next to it are affected while the rest of the puzzle doesn’t move.In Rochester, New York, the most recent earthquake was reported on March 29th, 2020. It was a 2.6 magnitude shake centered under Lake Ontario. While most did not feel it, there were 54 reports of the ground shaking.So next time you are wondering why the dishes rattled, or you thought you felt the ground move, it certainly could have been an earthquake in New York.Here is a website from the USGS (United Sates Geologic Society) of current earthquakes greater than 2.5 during the past day around the world. As you can see, the Earth is a geologically active planet!Another great website of earthquakes that have occurred locally can be found here.To learn more about the science behind earthquakes, check out this website from the USGS.