The Sixth Seal Is Long Overdue (Rev 6)

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

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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

Columbia University Warns Of Sixth Seal (Revelation 6:12)

Earthquakes May Endanger New York More Than Thought, Says Study

New-York-Destroyed-300x224

A study by a group of prominent seismologists suggests that a pattern of subtle but active faults makes the risk of earthquakes to the New York City area substantially greater than formerly believed. Among other things, they say that the controversial Indian Point nuclear power plants, 24 miles north of the city, sit astride the previously unidentified intersection of two active seismic zones. The paper appears in the current issue of the Bulletin of the Seismological Society of America.

Many faults and a few mostly modest quakes have long been known around New York City, but the research casts them in a new light. The scientists say the insight comes from sophisticated analysis of past quakes, plus 34 years of new data on tremors, most of them perceptible only by modern seismic instruments. The evidence charts unseen but potentially powerful structures whose layout and dynamics are only now coming clearer, say the scientists. All are based at Columbia University’s Lamont-Doherty Earth Observatory, which runs the network of seismometers that monitors most of the northeastern United States.

Lead author Lynn R. Sykes said the data show that large quakes are infrequent around New York compared to more active areas like California and Japan, but that the risk is high, because of the overwhelming concentration of people and infrastructure. “The research raises the perception both of how common these events are, and, specifically, where they may occur,” he said. “It’s an extremely populated area with very large assets.” Sykes, who has studied the region for four decades, is known for his early role in establishing the global theory of plate tectonics.

The authors compiled a catalog of all 383 known earthquakes from 1677 to 2007 in a 15,000-square-mile area around New York City. Coauthor John Armbruster estimated sizes and locations of dozens of events before 1930 by combing newspaper accounts and other records. The researchers say magnitude 5 quakes—strong enough to cause damage–occurred in 1737, 1783 and 1884. There was little settlement around to be hurt by the first two quakes, whose locations are vague due to a lack of good accounts; but the last, thought to be centered under the seabed somewhere between Brooklyn and Sandy Hook, toppled chimneys across the city and New Jersey, and panicked bathers at Coney Island. Based on this, the researchers say such quakes should be routinely expected, on average, about every 100 years. “Today, with so many more buildings and people, a magnitude 5 centered below the city would be extremely attention-getting,” said Armbruster. “We’d see billions in damage, with some brick buildings falling. People would probably be killed.”

Starting in the early 1970s Lamont began collecting data on quakes from dozens of newly deployed seismometers; these have revealed further potential, including distinct zones where earthquakes concentrate, and where larger ones could come. The Lamont network, now led by coauthor Won-Young Kim, has located hundreds of small events, including a magnitude 3 every few years, which can be felt by people at the surface, but is unlikely to cause damage. These small quakes tend to cluster along a series of small, old faults in harder rocks across the region. Many of the faults were discovered decades ago when subways, water tunnels and other excavations intersected them, but conventional wisdom said they were inactive remnants of continental collisions and rifting hundreds of millions of years ago. The results clearly show that they are active, and quite capable of generating damaging quakes, said Sykes.

One major previously known feature, the Ramapo Seismic Zone, runs from eastern Pennsylvania to the mid-Hudson Valley, passing within a mile or two northwest of Indian Point. The researchers found that this system is not so much a single fracture as a braid of smaller ones, where quakes emanate from a set of still ill-defined faults. East and south of the Ramapo zone—and possibly more significant in terms of hazard–is a set of nearly parallel northwest-southeast faults. These include Manhattan’s 125th Street fault, which seems to have generated two small 1981 quakes, and could have been the source of the big 1737 quake; the Dyckman Street fault, which carried a magnitude 2 in 1989; the Mosholu Parkway fault; and the Dobbs Ferry fault in suburban Westchester, which generated the largest recent shock, a surprising magnitude 4.1, in 1985. Fortunately, it did no damage. Given the pattern, Sykes says the big 1884 quake may have hit on a yet-undetected member of this parallel family further south.

The researchers say that frequent small quakes occur in predictable ratios to larger ones, and so can be used to project a rough time scale for damaging events. Based on the lengths of the faults, the detected tremors, and calculations of how stresses build in the crust, the researchers say that magnitude 6 quakes, or even 7—respectively 10 and 100 times bigger than magnitude 5–are quite possible on the active faults they describe. They calculate that magnitude 6 quakes take place in the area about every 670 years, and sevens, every 3,400 years. The corresponding probabilities of occurrence in any 50-year period would be 7% and 1.5%. After less specific hints of these possibilities appeared in previous research, a 2003 analysis by The New York City Area Consortium for Earthquake Loss Mitigation put the cost of quakes this size in the metro New York area at $39 billion to $197 billion. A separate 2001 analysis for northern New Jersey’s Bergen County estimates that a magnitude 7 would destroy 14,000 buildings and damage 180,000 in that area alone. The researchers point out that no one knows when the last such events occurred, and say no one can predict when they next might come.

“We need to step backward from the simple old model, where you worry about one large, obvious fault, like they do in California,” said coauthor Leonardo Seeber. “The problem here comes from many subtle faults. 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. We need to take a very close look.” Seeber says that because the faults are mostly invisible at the surface and move infrequently, a big quake could easily hit one not yet identified. “The probability is not zero, and the damage could be great,” he said. “It could be like something out of a Greek myth.”

The researchers found concrete evidence for one significant previously unknown structure: an active seismic zone running at least 25 miles from Stamford, Conn., to the Hudson Valley town of Peekskill, N.Y., where it passes less than a mile north of the Indian Point nuclear power plant. The Stamford-Peekskill line stands out sharply on the researchers’ earthquake map, with small events clustered along its length, and to its immediate southwest. Just to the north, there are no quakes, indicating that it represents some kind of underground boundary. It is parallel to the other faults beginning at 125th Street, so the researchers believe it is a fault in the same family. Like the others, they say it is probably capable of producing at least a magnitude 6 quake. Furthermore, a mile or so on, it intersects the Ramapo seismic zone.

Sykes said the existence of the Stamford-Peekskill line had been suggested before, because the Hudson takes a sudden unexplained bend just ot the north of Indian Point, and definite traces of an old fault can be along the north side of the bend. The seismic evidence confirms it, he said. “Indian Point is situated at the intersection of the two most striking linear features marking the seismicity and also in the midst of a large population that is at risk in case of an accident,” says the paper. “This is clearly one of the least favorable sites in our study area from an earthquake hazard and risk perspective.”

The findings comes at a time when Entergy, the owner of Indian Point, is trying to relicense the two operating plants for an additional 20 years—a move being fought by surrounding communities and the New York State Attorney General. Last fall the attorney general, alerted to the then-unpublished Lamont data, told a Nuclear Regulatory Commission panel in a filing: “New data developed in the last 20 years disclose a substantially higher likelihood of significant earthquake activity in the vicinity of [Indian Point] that could exceed the earthquake design for the facility.” The state alleges that Entergy has not presented new data on earthquakes past 1979. However, in a little-noticed decision this July 31, the panel rejected the argument on procedural grounds. A source at the attorney general’s office said the state is considering its options.

The characteristics of New York’s geology and human footprint may increase the problem. Unlike in California, many New York quakes occur near the surface—in the upper mile or so—and they occur not in the broken-up, more malleable formations common where quakes are frequent, but rather in the extremely hard, rigid rocks underlying Manhattan and much of the lower Hudson Valley. Such rocks can build large stresses, then suddenly and efficiently transmit energy over long distances. “It’s like putting a hard rock in a vise,” said Seeber. “Nothing happens for a while. Then it goes with a bang.” Earthquake-resistant building codes were not introduced to New York City until 1995, and are not in effect at all in many other communities. Sinuous skyscrapers and bridges might get by with minimal damage, said Sykes, but many older, unreinforced three- to six-story brick buildings could crumble.

Art Lerner-Lam, associate director of Lamont for seismology, geology and tectonophysics, pointed out that the region’s major highways including the New York State Thruway, commuter and long-distance rail lines, and the main gas, oil and power transmission lines all cross the parallel active faults, making them particularly vulnerable to being cut. Lerner-Lam, who was not involved in the research, said that the identification of the seismic line near Indian Point “is a major substantiation of a feature that bears on the long-term earthquake risk of the northeastern United States.” He called for policymakers to develop more information on the region’s vulnerability, to take a closer look at land use and development, and to make investments to strengthen critical infrastructure.

“This is a landmark study in many ways,” said Lerner-Lam. “It gives us the best possible evidence that we have an earthquake hazard here that should be a factor in any planning decision. It crystallizes the argument that this hazard is not random. There is a structure to the location and timing of the earthquakes. This enables us to contemplate risk in an entirely different way. And since we are able to do that, we should be required to do that.”

New York Earthquake Briefs and Quotes:

Existing U.S. Geological Survey seismic hazard maps show New York City as facing more hazard than many other eastern U.S. areas. Three areas are somewhat more active—northernmost New York State, New Hampshire and South Carolina—but they have much lower populations and fewer structures. The wider forces at work include pressure exerted from continuing expansion of the mid-Atlantic Ridge thousands of miles to the east; slow westward migration of the North American continent; and the area’s intricate labyrinth of old faults, sutures and zones of weakness caused by past collisions and rifting.

Due to New York’s past history, population density and fragile, interdependent infrastructure, a 2001 analysis by the Federal Emergency Management Agency ranks it the 11th most at-risk U.S. city for earthquake damage. Among those ahead: Los Angeles, San Francisco, Seattle and Portland. Behind: Salt Lake City, Sacramento, Anchorage.

New York’s first seismic station was set up at Fordham University in the 1920s. Lamont-Doherty Earth Observatory, in Palisades, N.Y., has operated stations since 1949, and now coordinates a network of about 40.

Dozens of small quakes have been felt in the New York area. A Jan. 17, 2001 magnitude 2.4, centered in the Upper East Side—the first ever detected in Manhattan itself–may have originated on the 125th Street fault. Some people thought it was an explosion, but no one was harmed.

The most recent felt quake, a magnitude 2.1 on July 28, 2008, was centered near Milford, N.J. Houses shook and a woman at St. Edward’s Church said she felt the building rise up under her feet—but no damage was done.

Questions about the seismic safety of the Indian Point nuclear power plant, which lies amid a metropolitan area of more than 20 million people, were raised in previous scientific papers in 1978 and 1985.

Because the hard rocks under much of New York can build up a lot strain before breaking, researchers believe that modest faults as short as 1 to 10 kilometers can cause magnitude 5 or 6 quakes.

In general, magnitude 3 quakes occur about 10 times more often than magnitude fours; 100 times more than magnitude fives; and so on. This principle is called the Gutenberg-Richter relationship.

The Sixth Seal: Real Risk, Few Precautions (Revelation 6:12)

Eastern Quakes: Real Risk, Few Precautions

1989 San Francisco Earthquake

1989 San Francisco Earthquake

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.”

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.”

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

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

Did You Feel the Virginia 2011 Earthquake?

Did You Feel the Virginia 2011 Earthquake?

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 km2 from 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.

 

The Next Big ONE: The Sixth Seal Of New York City (Revelation 6:12)

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

Ramapo Fault Line

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

Economic Consequences of the Sixth Seal (Revelation 6:12)

Scenario Earthquakes for Urban Areas Along the Atlantic Seaboard of the United States

NYCEM.org

New York City Area Consortium for Earthquake Loss Mitigation

If today a magnitude 6 earthquake were to occur centered on New York City, what would its effects be? Will the loss be 10 or 100 billion dollars? Will there be 10 or 10,000 fatalities? Will there be 1,000 or 100,000 homeless needing shelter? Can government function, provide assistance, and maintain order?

At this time, no satisfactory answers to these questions are available. A few years ago, rudimentary scenario studies were made for Boston and New York with limited scope and uncertain results. For most eastern cities, including Washington D.C., we know even less about the economic, societal and political impacts from significant earthquakes, whatever their rate of occurrence.

Why do we know so little about such vital public issues? Because the public has been lulled into believing that seriously damaging quakes are so unlikely in the east that in essence we do not need to consider them. We shall examine the validity of this widely held opinion.

Is the public’s earthquake awareness (or lack thereof) controlled by perceived low Seismicity, Seismic Hazard, or Seismic Risk? How do these three seismic features differ from, and relate to each other? In many portions of California, earthquake awareness is refreshed in a major way about once every decade (and in some places even more often) by virtually every person experiencing a damaging event. The occurrence of earthquakes of given magnitudes in time and space, not withstanding their effects, are the manifestations of seismicity. Ground shaking, faulting, landslides or soil liquefaction are the manifestations of seismic hazard. Damage to structures, and loss of life, limb, material assets, business and services are the manifestations of seismic risk. By sheer experience, California’s public understands fairly well these three interconnected manifestations of the earthquake phenomenon. This awareness is reflected in public policy, enforcement of seismic regulations, and preparedness in both the public and private sector. In the eastern U.S., the public and its decision makers generally do not understand them because of inexperience. Judging seismic risk by rates of seismicity alone (which are low in the east but high in the west) has undoubtedly contributed to the public’s tendency to belittle the seismic loss potential for eastern urban regions.

Let us compare two hypothetical locations, one in California and one in New York City. Assume the location in California does experience, on average, one M = 6 every 10 years, compared to New York once every 1,000 years. This implies a ratio of rates of seismicity of 100:1. Does that mean the ratio of expected losses (when annualized per year) is also 100:1? Most likely not. That ratio may be closer to 10:1, which seems to imply that taking our clues from seismicity alone may lead to an underestimation of the potential seismic risks in the east. Why should this be so?

To check the assertion, let us make a back-of-the-envelope estimate. The expected seismic risk for a given area is defined as the area-integrated product of: seismic hazard (expected shaking level), assets ($ and people), and the assets’ vulnerabilities (that is, their expected fractional loss given a certain hazard – say, shaking level). Thus, if we have a 100 times lower seismicity rate in New York compared to California, which at any given point from a given quake may yield a 2 times higher shaking level in New York compared to California because ground motions in the east are known to differ from those in the west; and if we have a 2 times higher asset density (a modest assumption for Manhattan!), and a 2 times higher vulnerability (again a modest assumption when considering the large stock of unreinforced masonry buildings and aged infrastructure in New York), then our California/New York ratio for annualized loss potential may be on the order of (100/(2x2x2)):1. That implies about a 12:1 risk ratio between the California and New York location, compared to a 100:1 ratio in seismicity rates.

From this example it appears that seismic awareness in the east may be more controlled by the rate of seismicity than by the less well understood risk potential. This misunderstanding is one of the reasons why earthquake awareness and preparedness in the densely populated east is so disproportionally low relative to its seismic loss potential. Rare but potentially catastrophic losses in the east compete in attention with more frequent moderate losses in the west. New York City is the paramount example of a low-probability, high-impact seismic risk, the sort of risk that is hard to insure against, or mobilize public action to reduce the risks.

There are basically two ways to respond. One is to do little and wait until one or more disastrous events occur. Then react to these – albeit disastrous – “windows of opportunity.” That is, pay after the unmitigated facts, rather than attempt to control their outcome. This is a high-stakes approach, considering the evolved state of the economy. The other approach is to invest in mitigation ahead of time, and use scientific knowledge and inference, education, technology transfer, and combine it with a mixture of regulatory and/or economic incentives to implement earthquake preparedness. The National Earthquake Hazard Reduction Program (NEHRP) has attempted the latter while much of the public tends to cling to the former of the two options. Realistic and reliable quantitative loss estimation techniques are essential to evaluate the relative merits of the two approaches.

This paper tries to bring into focus some of the seismological factors which are but one set of variables one needs for quantifying the earthquake loss potential in eastern U.S. urban regions. We use local and global analogs for illustrating possible scenario events in terms of risk. We also highlight some of the few local steps that have been undertaken towards mitigating against the eastern earthquake threat; and discuss priorities for future actions.

Next article September 29, 2014

A Closer Look At The Sixth Seal (Rev 6:12)

A Look at the Tri-State’s Active Fault Line

Ramapo

Monday, March 14, 2011

 

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.

East Coast Expecting The Sixth Seal (Revelation 6:12)

United States Fault Lines Map – Earthquakes could also happen in East Coast and in the Midwest Cites

Fault Lines US

[BestSyndication News] Earthquakes are always a concern out in Alaska and in California, as it is full of fault lines that are continually shifting. There are some fault lines that are overdue to shift, especially the California San Andres fault line that runs through the mountain ranges and close to Wrightwood. But did you know there is a United States Fault Lines Map that illustrates great potentials for earthquakes outside of our state?

New Madrid Fault Line

The New Madrid Fault Line has records of over 4000 earthquake reports since 1974. This fault line is also called the New Madrid Seismic Zone and has potential to devastate the states of Illinois, Indiana, Missouri, Arkansas, Kentucky, Tennessee, and Mississippi. The biggest part of the New Madrid Fault Line sits in Missouri.

We often forget that this Midwestern fault line is there, but in 1811-1812 there was a series of earthquakes that shook with estimated magnitudes of 8.1 – 8.3, with several aftershocks of 6.0 magnitudes. Since those big ones, the largest earthquake that this fault line produced was in a 6.6-magnitude quake that happened on October 31, 1895. It’s epicenter was in Charleston, Missouri.The damage from these earthquakes were extensive, and there has been recent speculation by the scientific community that believe that this fault line might be shutting down and moving elsewhere. In an issue of Nature, scientist believe the current seismic activity at the New Madrid Fault line is only aftershocks from the earthquake back in 1811 and 1812.

Ramapo Fault Line

The Ramapo Fault Line spans 300 kilometers and affects the states of New York, New Jersey, and Pennsylvania. These faults run between the Appalachian Mountains and Piedmont areas to the east.

This fault remains relatively inactive, but scientists believe that it could produce some serious earthquakes. There was a study completed in 2008 that believes a 6 – 7 magnitude earthquake will very likely occur from this fault line. The last time this fault was the most active was believed to be 200 million years ago.

San Andreas Fault Line

The last few years Southern California has been preparing for the next big one with government sponsored Earthquake Drills. Scientist are predicting that the next big one with a magnitude of a 7.0 or higher for this fault line will happen any time, it could be now or 10 years from now. They believe the areas that are going to be hit the hardest are going to be Palm Springs and a number of other cities in San Bernardino, Riverside and Imperial counties in California, and Mexicali municipality in Baja California.

To learn more about earthquakes you can visit http://earthquake.usgs.gov/learn/

The Ramapo Fault and the Sixth Seal (Revelation 6:12)

Living on the Fault LineRamapo_Fault_Line

A major earthquake isn’t likely here, but if it comes, watch out.

Posted June 15, 2010 by Wayne J. Guglielmo

This chart shows the location of the Ramapo Fault System, the longest and one of the oldest systems of cracks in the earth’s crust in the Northeast. It also shows the location of all earthquakes of magnitude 2.5 or greater in New Jersey during the last 50 years. The circle in blue indicates the largest known Jersey quake.

The couple checked with Burns’s parents, who live in nearby Basking Ridge, and they, too, had heard and felt something, which they thought might have been an earthquake. A call by Burns some 20 minutes later to the Bernardsville Police Department—one of many curious and occasionally panicky inquiries that Sunday morning, according to the officer in charge, Sergeant John Remian—confirmed their suspicion: A magnitude 2.6 earthquake, its epicenter in Peapack/Gladstone, about seven miles from Bernardsville, had hit the area. A smaller aftershock followed about two and a half hours later.

After this year’s epic earthquakes in Haiti, Chile, Mexico, Indonesia, and China, the 2.6 quake and aftershock that shook parts of New Jersey in February may seem minor league, even to the Somerset County residents who experienced them. On the exponential Richter Scale, a magnitude 7.0 quake like the one that hit Haiti in January is almost 4 million times stronger than a quake of 2.6 magnitude. But comparisons of magnitude don’t tell the whole story.

Northern New Jersey straddles the Ramapo Fault, a significant ancient crack in the earth’s crust. The longest fault in the Northeast, it begins in Pennsylvania and moves into New Jersey, trending northeast through Hunterdon, Somerset, Morris, Passaic, and Bergen counties before terminating in New York’s Westchester County, not far from the Indian Point Energy Center, a nuclear power plant. And though scientists dispute how active this roughly 200 million-year-old fault really is, many earthquakes in the state’s surprisingly varied seismic history are believed to have occurred on or near it. The fault line is visible at ground level and likely extends as deep as nine miles below the surface.

During the past 230 years or so, New Jersey has been at the epicenter of nearly 170 earthquakes, according to data compiled by the New Jersey Geological Survey, part of the United States Department of Environmental Protection. The largest known quake struck in 1783, somewhere west of New York City, perhaps in Sussex County. It’s typically listed as 5.3 in magnitude, though that’s an estimate by seismologists who are quick to point out that the concept of magnitude—measuring the relative size of an earthquake—was not introduced until 1935 by Charles Richter and Beno Gutenberg. Still, for quakes prior to that, scientists are not just guessing.

“We can figure out the damage at the time by going back to old records and newspaper accounts,” says Won-Young Kim, a senior research scientist at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York, directly across the New Jersey border. “Once the amount and extent of contemporary damage has been established,” Kim says, “we’re then able to gauge the pattern of ground shaking or intensity of the event—and from there extrapolate its probable magnitude.”

Other earthquakes of magnitude 5 or higher have been felt in New Jersey, although their epicenters laying near New York City. One—which took place in 1737 and was said to have been felt as far north as Boston and as far south as northern Delaware—was probably in the 5 to 5.5 range. In 1884, an earthquake of similar magnitude occurred off New York’s Rockaway Beach. This well-documented event pulled houses off their foundations and caused steeples to topple as far west as Rahway. The shock wave, scientists believe, was felt over 70,000 square miles, from Vermont to Maryland.

Among the largest sub-5 magnitude earthquakes with epicenters in New Jersey, two (a 3.8 and a 4.0) took place on the same day in 1938 in the Lakehurst area in Ocean County. On August 26, 2003, a 3.5 magnitude quake shook the Frenchtown/Milford area in Hunterdon County. On February 3 of last year, a 3.0 magnitude quake occurred in the Morris County town of Mendham. “A lot of people felt this one because of the intense shaking, although the area of intensity wasn’t very wide,” says Lamont-Doherty’s Kim, who visited the site after the event.

After examining the known historical and geological record, Kim and other seismologists have found no clear evidence that an earthquake of greater than 5.3 to 5.5 magnitude has taken place in this area going back to 1737. This doesn’t mean, of course, that one did not take place in the more remote past or that one will not occur in the future; it simply means that a very large quake is less likely to occur here than in other places in the east where the seismic hazard is greater, including areas in South Carolina and northeastern New York State.

But no area on the East Coast is as densely populated or as heavily built-up as parts of New Jersey and its neighbors. For this reason, scientists refer to the Greater New York City-Philadelphia area, which includes New Jersey’s biggest cities, as one of “low earthquake hazard but high vulnerability.” Put simply, the Big One isn’t likely here—but if it comes, especially in certain locations, watch out.

Given this low-hazard, high-vulnerability scenario, how far along are scientists in their efforts to predict larger magnitude earthquakes in the New Jersey area? The answer is complex, complicated by the state’s geographical position, its unique geological history, the state of seismology itself, and the continuing debate over the exact nature and activity of the Ramapo Fault.

Over millions of years, New Jersey developed four distinct physiographic provinces or regions, which divide the state into a series of diagonal slices, each with its own terrain, rock type, and geological landforms.

The northernmost slice is the Valley and Ridge, comprising major portions of Sussex and Warren counties. The southernmost slice is the Coastal Plain, a huge expanse that covers some three-fifths of the state, including all of the Shore counties. Dividing the rest of the state are the Highlands, an area for the most part of solid but brittle rock right below the Valley and Ridge, and the lower lands of the Piedmont, which occupy all of Essex, Hudson, and Union counties, most of Bergen, Hunterdon, and Somerset, and parts of Middlesex, Morris, and Passaic.

For earthquake monitors and scientists, the formation of these last two provinces—the Highlands and the Piedmont—are of special interest. To understand why, consider that prior to the appearance of the Atlantic Ocean, today’s Africa was snuggled cozily up against North America and surrounded by a single enormous ocean. “At that point, you could have had exits off the New Jersey Turnpike for Morocco,” says Alexander Gates, professor of geology and chair of the department of Earth and Environmental Sciences at Rutgers-Newark.

Under the pressure of circulating material within the Earth’s super-hot middle layer, or mantle, what was once a single continent—one that is thought to have included today’s other continents as well—began to stretch and eventually break, producing numerous cracks or faults and ultimately separating to form what became the Atlantic Ocean. In our area, the longest and most active of these many cracks was the Ramapo Fault, which, through a process known as normal faulting, caused one side of the earth’s crust to slip lower—the Piedmont—relative to the other side—the Highlands. “All this occurred about 225 million years ago,” says Gates. “Back then, you were talking about thousands of feet between the Highlands and the Piedmont and a very active Ramapo Fault.”

The Earth’s crust, which is 20 to 25 miles thick, is not a single, solid shell, but is broken into seven vast tectonic plates, which drift atop the soft, underlying mantle. Although the northeast-trending Ramapo Fault neatly divides two of New Jersey’s four physiographic provinces, it does not form a so-called plate boundary, as does California’s infamous San Andreas Fault. As many Californians know all too well, this giant fault forms the boundary between two plates—to the west, the Pacific Plate, and to the east, the North American Plate; these rub up against each other, producing huge stresses and a regularly repeating pattern of larger earthquakes.

The Ramapo Fault sits on the North American Plate, which extends past the East Coast to the middle of the Atlantic, where it meets the Mid-Atlantic Ridge, an underwater mountain range in constant flux. The consequences of this intraplate setting are huge: First, as Gates points out, “The predictability of bigger earthquakes on…[such] settings is exceedingly poor, because they don’t occur very often.” Second, the intraplate setting makes it more difficult to link our earthquakes to a major cause or fault, as monitors in California can often do.

This second bit of uncertainty is especially troubling for some people, including some in the media who want a neat story. To get around it, they ignore the differences between plate settings and link all of New Jersey’s earthquakes, either directly or implicitly, to the Ramapo Fault. In effect, such people want the Ramapo Fault “to look like the San Andreas Fault,” says Gates. “They want to be able to point to one big fault that’s causing all of our earthquakes.”

Gates does not think that’s the case, and he has been working with colleagues for a number of years to prove it. “What we have found is that there are smaller faults that generally cut from east to west across the northeast-trending Ramapo Fault,” he explains. “These much smaller faults are all over the place, and they’re actually the ones that are the active faults in the area.”

But what mechanisms are responsible for the formation of these apparently active auxiliary faults? One such mechanism, say scientists, is the westward pressure the Atlantic Ocean exerts on the North American Plate, which for the most part resists any movement. “I think we are in an equilibrium state most of the time,” says Lamont-Doherty’s Kim.

Still, that continuous pressure on the plate we sit on causes stress, and when that stress builds up sufficiently, the earth’s crust has a tendency to break around any weak zones. In our area, the major weak zone is the Ramapo Fault—“an ancient zone of weakness,” as Kim calls it. That zone of weakness exacerbates the formation of auxiliary faults, and thereby the series of minor earthquakes the state has experienced over the years.

All this presupposes, of course, that any intraplate stress in this area will continue to be released gradually, in a series of relatively minor earthquakes or releases of energy. But what if that were not the case? What if the stress continued to build up, and the release of large amounts of energy came all at once? In crude terms, that’s part of the story behind the giant earthquakes that rocked what is now New Madrid, Missouri, between 1811 and 1812. Although estimates of their magnitude have been revised downward in recent years to less than magnitude 8, these earthquakes are generally regarded as among the largest intraplate events to have occurred in the continental United States.

For a number of reasons—including the relatively low odds that the kind of stored energy that unleashed the New Madrid events could ever build up here—earthquakes of plus-6 magnitude are probably not in our future. Still, says Kim, even a magnitude 6 earthquake in certain areas of the state could do considerable damage, especially if its intensity or ground shaking was of sufficient strength. In a state as geologically diverse and densely populated as New Jersey, this is a crucial wild card.

Part of the job of the experts at the New Jersey Geological Survey is to assess the seismic hazards in different parts of the state. To do this, they use a computer-simulation model developed under the direction of the Federal Emergency Management Agency, known as HAZUS, for Hazards US. To assess the amount of ground shaking likely to occur in a given county during events ranging in magnitude from 5 to 7 on the Richter Scale, NJGS scientists enter three features of a county’s surface geology into their computer model. Two of these features relate to the tendency of soil in a given area to lose strength, liquefy, or slide downhill when shaken. The third and most crucial feature has to do with the depth and density of the soil itself and the type of bedrock lying below it; this is a key component in determining a region’s susceptibility to ground shaking and, therefore, in estimating the amount of building and structural damage that’s likely to occur in that region. Estimates for the various counties—nine to date have been studied—are sent to the New Jersey Office of Emergency Management, which provided partial funding for the project.

To appreciate why this element of ground geology is so crucial to earthquake modelers, consider the following: An earthquake’s intensity—which is measured on something called the Modified Mercalli Scale—is related to a number of factors. The amount of energy released or the magnitude of an event is clearly a big factor. But two earthquakes of the same magnitude can have very different levels of intensity; in fact, it’s quite possible for a lower magnitude event to generate more ground shaking than a higher magnitude one.

In addition to magnitude, other factors that affect intensity are the distance of the observer or structure from the epicenter, where intensity is the greatest; the depth beneath the surface of the initial rupture, with shallower ruptures producing more ground shaking than deeper ones; and, most significantly, the ground geology or material that the shock wave generated by the earthquake must pass through.

As a rule, softer materials like sand and gravel shake much more intensely than harder materials, because the softer materials are comparatively inefficient energy conductors, so whatever energy is released by the quake tends to be trapped, dispersing much more slowly. (Think of a bowl of Jell-O on a table that’s shaking.)

In contrast, harder materials, like the solid rock found widely in the Highlands, are brittle and break under pressure, but conduct energy well, so that even big shock waves disperse much more rapidly through them, thereby weakening the amount of ground shaking. “If you’ve read any stories about the 1906 earthquake in San Francisco, you know the most intense damage was in those flat, low areas by the Bay, where the soil is soft, and not in the hilly, rocky areas above,” says Karl Muessig, state geologist and NJGS head.

The map that accompanies the online version of the NJGS’s Earthquake Loss Estimation Study divides the state’s surface geology into five seismic soil classes, ranging from Class A, or hard rock, to Class E, or soft soil (state.nj.us/dep/njgs/enviroed/hazus.htm).

Although the weakest soils are scattered throughout the state, including the Highlands, which besides harder rock also contains areas of glacial lakes, clays, and wetlands, they are most evident in the Piedmont and the Coastal Plain. “The largest expanses of them are in coastal areas where you have salt marshes or large glacial lakes, as in parts of the Passaic River basin,” says Scott Stanford, a research scientist with NJGS and lead author of the estimate. Some of the very weakest soils, Stanford adds, are in areas of filled marshland, including places along the Hudson waterfront, around Newark Bay and the Meadowlands, and along the Arthur Kill.

Faults in these areas—and in the coastal plain generally—are far below the ground, perhaps several hundred to a thousand feet down, making identification difficult. “There are numerous faults upon which you might get earthquake movement that we can’t see, because they’re covered by younger sediments,” Stanford says.

This combination of hidden faults and weak soils worries scientists, who are all too aware that parts of the coastal plain and Piedmont are among the most densely populated and developed areas in the state. (The HAZUS computer model also has a “built environment” component, which summarizes, among other things, types of buildings in a given area.) For this reason, such areas would be in the most jeopardy in the event of a large earthquake.

“Any vulnerable structure on these weak soils would have a higher failure hazard,” Stanford says. And the scary truth is that many structures in New Jersey’s largest cities, not to mention New York City, would be vulnerable, since they’re older and built before anyone gave much thought to earthquake-related engineering and construction codes.

For example, in the study’s loss estimate for Essex County, which includes Newark, the state’s largest city, a magnitude 6 event would result in damage to 81,600 buildings, including almost 10,000 extensively or completely; 36,000 people either displaced from their homes or forced to seek short-term shelter; almost $9 million in economic losses from property damage and business interruption; and close to 3,300 injuries and 50 fatalities. (The New York City Area Consortium for Earthquake Loss Mitigation has conducted a similar assessment for New York City, at nycem.org.)

All of this suggests the central irony of New Jersey geology: The upland areas that are most prone to earthquakes—the counties in or around the Ramapo Fault, which has spawned a network of splays, or auxiliary faults—are much less densely populated and sit, for the most part, on good bedrock. These areas are not invulnerable, certainly, but, by almost all measures, they would not sustain very severe damage, even in the event of a higher magnitude earthquake. The same can’t be said for other parts of the state, where the earthquake hazard is lower but the vulnerability far greater. Here, the best we can do is to prepare—both in terms of better building codes and a constantly improving emergency response.

Meanwhile, scientists like Rutgers’s Gates struggle to understand the Earth’s quirky seismic timetable: “The big thing with earthquakes is that you can commonly predict where they are going to occur,” Gates says. “When they’re going to come, well, we’re nowhere near being able to figure that out.”

***********************

Planning for the Big One

For the men and women of the state police who manage and support the New Jersey Office of Emergency Management (OEM), the response to some events, like hurricanes, can be marshalled in advance. But an earthquake is what responders call a no-notice event.

In New Jersey, even minor earthquakes—like the one that shook parts of Somerset County in February—attract the notice of local, county, and OEM officials, who continuously monitor events around the state from their Regional Operations and Intelligence Center (The ROIC) in West Trenton, a multimillion dollar command-and-control facility that has been built to withstand 125 mph winds and a 5.5 magnitude earthquake. In the event of a very large earthquake, during which local and county resources are apt to become quickly overwhelmed, command and control authority would almost instantly pass to West Trenton.

Here, officials from the state police, representatives of a galaxy of other state agencies, and a variety of communications and other experts would assemble in the cavernous and ultra-high tech Emergency Operations Center to oversee the state’s response. “A high-level earthquake would definitely cause the governor to declare a state of emergency,” says OEM public information officer Nicholas J. Morici. “And once that takes place, our emergency operations plan would be put in motion.”

Emergency officials have modeled that plan—one that can be adapted to any no-notice event, including a terrorist attack—on response methodologies developed by the Federal Emergency Management Agency (FEMA), part of the U.S. Department of Homeland Security. At its core is a series of seventeen emergency support functions, ranging from transportation to firefighting, debris removal, search and rescue, public health, and medical services. A high-magnitude event would likely activate all of these functions, says Morici, along with the human and physical resources needed to carry them out—cranes and heavy trucks for debris removal, fire trucks and teams for firefighting, doctors and EMTs for medical services, buses and personnel carriers for transportation, and so on.

This is where an expert like Tom Rafferty comes in. Rafferty is a Geographic Information Systems Specialist attached to the OEM. His job during an emergency is to keep track electronically of which resources are where in the state, so they can be deployed quickly to where they are needed. “We have a massive database called the Resource Directory Database in which we have geolocated municipal, county, and state assets to a very detailed map of New Jersey,” Rafferty says. “That way, if there is an emergency like an earthquake going on in one area, the emergency managers can quickly say to me, for instance, ‘We have major debris and damage on this spot of the map. Show us the location of the nearest heavy hauler. Show us the next closest location,’ and so on.”

A very large quake, Rafferty says, “could overwhelm resources that we have as a state.” In that event, OEM has the authority to reach out to FEMA for additional resources and assistance. It can also call upon the private sector—the Resource Directory has been expanded to include non-government assets—and to a network of volunteers. “No one has ever said, ‘We don’t want to help,’” Rafferty says. New Jersey officials can also request assistance through the Emergency Management Assistance Compact (EMAC), an agreement among the states to help each other in times of extreme crisis.

“You always plan for the worst,” Rafferty says, “and that way when the worst doesn’t happen, you feel you can handle it if and when it does.”

Contributing editor Wayne J. Guglielmo lives in Mahwah, near the Ramapo Fault.

The Next Big ONE: The Sixth Seal Of New York City

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

Ramapo Fault Line

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