New Madrid Fault
August 23, 2011 by staff
The earthquake that shook Washington, DC, New York and parts from Tuesday afternoon was unusual but did not come as a complete surprise to geologists. While four-fifths of the world’s largest earthquakes occur on tectonic belt takes in California, Japan and Indonesia, smaller risk areas are scattered throughout the eastern United States, as this seismic risk map shows . Recent research suggests some of them might be related to a failure mysterious ancient runs clear from Alabama to New York.
In fact, 39 of 50 states – including New York and Tennessee – have a moderate risk to high seismic risk, ABC Good Morning America last year. The New Madrid fault, which runs from St. Louis to Memphis, is one of the most dangerous country. Between 1811 and 1812 was the scene of a series of earthquakes larger than any recorded in California, causing damage as far away as Washington, DC and Charleston, South Carolina
The Central Virginia is home to a smaller seismic zone, but the minor earthquakes have been reported there periodically for centuries, according to the USGS. Until Tuesday, however, the largest earthquake in the region had been a modest 4.8, again in 1875.
The 5.3 event in Colorado early Wednesday was also unusual. The New York Times reports that the quake was the state’s largest natural since 1882. A couple of recent earthquakes, a 5.3 near Denver in 1967 and 5.7 in northwestern Colorado in 1973 were caused by humans.
New Yorkers are not safe either. The Ramapo fault system that extends from southeastern New York to eastern Pennsylvania, has been known to cause earthquakes up to 5.2, according to Columbia University Earth Institute. Perhaps more worrisome from the standpoint of potential damage, the well-studied fault line 125th St., across the north of Manhattan from the Hudson River to the East River. It has not attracted much in the last 200 years, seismologists have some worried that it might be due. This story from the board to survive an earthquake, said: “Geologists estimate a probability of 20 percent to 40 percent of a major earthquake in the next 50 years in New York and make a special point to say that a large earthquake is also a real possibility. .. What has experts worried is the relationship particularly alarmingly high probability the city of preparation. ”
As tremor on Tuesday showed, even an earthquake centered in a large metropolitan area can cities big threat, especially in the East. According to an explainer of the USGS: “Earthquakes in central and eastern U.S., although less frequent than in the western U.S., are typically felt over a much wider region. East of the Rockies, an earthquake can be felt in an area ten times larger than a similar magnitude earthquake on the West Coast. ”
East curious about their risk of local earthquakes do not obsess over the exact location of fault lines, another USGS explainer says: “In California, a major earthquake usually can be associated with a particular fault, because we seen the fault rupture and displacement of the soil surface during the earthquake. By contrast, east of the Rockies things are less simple, since it is rare for earthquakes to break the soil surface. In particular, this Rocky Mountain, best known faults and failures seems to have nothing to do with modern earthquakes. We do not know why. “
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