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According to the United States Geological Survey, the quake struck at 12:28 am CT today

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Earthquake felt in Chilton County

By Mike Kelley (Contact) | Clanton Advertiser

Published Tuesday, April 21, 2009

An earthquake that occurred north of Centreville early Tuesday morning had many Chilton County residents calling the United States Geological Survey to report they believed they experienced an earthquake.

By mid-morning Tuesday, 21 county residents had reported they felt what they thought was an earthquake.

The USGS released a statement Tuesday that a 3.8-magnitude earthquake had occurred approximately four miles north of Centreville in Bibb County at 5:25 a.m.

The earthquake occurred, according to the USGS, 3.1 miles below the earth’s surface.

There have been no reports of injuries, deaths or damage caused by the earthquake.

Though the epicenter was approximately 56 miles from Clanton, residents heard and felt the earthquake. Others as far away as Alexander City reported they felt the earthquake.

Tuesday’s earthquake was the second to be reported this year in Bibb County. On February 18, an earthquake that measured 2.2 occurred approximately 10 miles south of Centreville.

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Probably too small to even be noticed, but goes to show that earthquakes are not just a possibility on the West Coast.

Small Earthquake Recorded on West Virginia Border
Posted Tuesday, April 14, 2009 ; 07:00 PM

Residents most likely did not feel it.ATHENS, West Virginia – Although residents in West Virginia and Virginia probably did not feel it, residents suffered a small earthquake over the weekend along the borders of the two states. The Southeast United States Seismic Network confirms the quake had a magnitude of 2.4. It happened at 11:09a.m. Saturday, April 11th. The recording showed it to be nine miles northeast of Athens, in Mercer County. There were no reports of damage or injuries.

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Earthquakes’ Many Mysteries Stymie Efforts to Predict Them

Almost all earthquakes are small. A small segment of a fault, miles underground, jerks a little, the rumble imperceptible at the surface. But with a few quakes, the fault continues breaking, the ground jumps several feet and the world shakes in cataclysm.

“How does a rupture go from an inch a year to 3,000 miles per hour in a few seconds?” asked Ross S. Stein, a geophysicist at the United States Geological Survey.

No one knows.

This gap in knowledge makes earthquake prediction a frustrating and chancy exercise, and complicates the effort to calculate the risk that a human construction like a water reservoir or a geothermal power plant could inadvertently set off a deadly quake.

Last month, Giampaolo Giuliani, a technician who works on a neutrino experiment at the Gran Sasso National Laboratory in Italy, issued an urgent warning that a large earthquake was about to strike the Abruzzo region. The prediction was based on measurements he had made of high levels of radon gas, presumably released from rocks that were being ground up by the stresses of an incipient quake.

On April 6, a magnitude 6.3 earthquake hit L’Aquila in central Italy, killing almost 300 people. Mr. Giuliani claimed vindication for his prediction, which had been discounted by officials.

But earthquake experts like Dr. Stein are skeptical. Scientists studied radon as a possible earthquake warning signal as far back as the 1970s, and while they found convincing cases of radon releases before some earthquakes — for example, levels of radon in groundwater were 10 times normal before the earthquake that hit Kobe, Japan, in 1995 — the correlations were not strong enough or clear enough for useful predictions.

One instance of confusing radon signals occurred in 1979. Two detectors in Southern California, 20 miles apart, measured unusually high levels of radon beginning in the summer. The radon levels then decreased in October, shortly before three earthquakes struck.

One earthquake, of magnitude 6.6, occurred 180 miles to the southeast, and the two smaller ones, of magnitudes 4.1 and 4.2, were 40 miles away. In addition, a radon detector close to one of the smaller quakes did not observe high radon levels, although it did observe a radon drop a few days earlier.

That left scientists puzzled about how they could construct a prediction out of the rising and falling radon levels. Data on other gases like carbon dioxide and on electromagnetic emissions that have sometimes been detected before earthquakes are also confusing.

“You can’t hang your hat on it unless it’s a reliable precursor and it happens before most earthquakes and it doesn’t happen at other times,” said Susan Hough, a seismologist at the geological survey.

To complicate matters, Mr. Giuliani’s prediction was off in time and place. He had predicted that the quake would hit a week earlier in a town 30 miles away. Had officials acted on his prediction, said Richard M. Allen, a professor of geophysics at the University of California, Berkeley, “you would have evacuated the wrong town and you would have evacuated the wrong town at the wrong time.”

While prediction remains elusive, scientists have learned that human activity can set off an earthquake. In December 2006, a geothermal energy project in Basel, Switzerland, started injecting water three miles into the ground. Some tiny tremors were expected, but the water was shut off when one of the quakes reached a still minor magnitude of 2.7. A few hours later, a larger quake, at magnitude 3.4, shook Basel, causing minor damage to buildings.

A couple of months later, there were two more magnitude 3 earthquakes. Researchers at the Swiss Federal Institute of Technology in Zurich calculate that the area will experience a slightly greater number of small earthquakes over the next 20 to 40 years as a result of the brief geothermal project, which remains halted.

The worry is that one of these small earthquakes could cascade into a big earthquake like the one that badly damaged Basel in 1356. Conversely, the small earthquakes could instead be relieving stress along a fault, reducing the likelihood of a larger quake.

“With the current knowledge, I can’t really tell you,” said Jochen Woessner, one of the Swiss scientists.

Geologists do not know how the pieces of the Earth’s crust that usually squeeze together tightly with high friction slip past each other smoothly during a large earthquake, as if sandpaper suddenly changed to Teflon. “It looks like friction is more a complicated beast than anyone would have imagined,” Dr. Stein said.

A core dug up from the San Andreas fault in California revealed the presence of talc, which could be acting as a lubricant during an earthquake. But from one core, scientists cannot tell whether this is typical of rocks around earthquake faults.

At a meeting of the Seismological Society of America last week in Monterey, Calif., a lively debate continued about whether big earthquakes are fundamentally different from small earthquakes or whether a big earthquake is just a small earthquake that did not stop. If big earthquakes are different, then it might be possible to detect them in the first few seconds of seismic waves and send out a warning. People would not have time to evacuate, but they might have enough time before the heaviest shaking to move to a safer location in a doorway or under a desk.

Reservoirs are also believed to induce some earthquakes. Most seismologists believe that a magnitude 6.5 earthquake in India in 1967 that killed about 200 people was set off by the weight of water in a reservoir that had been filled a few years earlier. A reservoir cannot generate an earthquake by itself, but it can act as a trigger to release accumulated tectonic stresses and hasten an earthquake by years or centuries.

More controversial is the assertion by some scientists that a magnitude 7.9 earthquake in Sichuan province in China last year that killed about 80,000 people was set off by the 320 million tons of water in a nearby reservoir.

Leonardo Seeber, a research scientist at the Lamont-Doherty Earth Observatory atColumbia University, is not sure about the Sichuan earthquake, but he believes that scientists and officials need to take more account of the risk of induced earthquakes.

For example, Dr. Seeber wonders whether a swarm of magnitude 4 earthquakes a couple of weeks ago around the Salton Sea in Southern California, close to one end of the San Andreas, might have been caused in part by a nearby geothermal power plant.

Extraction of oil from the ground may have set off other earthquakes, Dr. Seeber said. In the coming years, the proposed strategy to reduce global warming by capturing carbon dioxide from power plants and pumping it into the ground could create new earthquake risks.

So far, experiments in this kind of carbon sequestration have focused on whether it will work to keep carbon dioxide out of the air for centuries. But Dr. Seeber said this technology “has huge implications for triggering earthquakes.”

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It’s a light one.

Earthquake Shakes Imperial Valle

Written by Carroll Buckley

Saturday, 11 April 2009

An earthquake measuring 4.2 on the Richter Scale rattled the south end of the Imperial Valley Saturday evening. According to the United States Geological Survey – Cal Tech Seismic Network , the earthquake was centered in Baja California , about 27 miles south south east of Calexico , California. It was recorded at 7:19 P.M. Saturday. There are no reports of damage from the light earthquake.

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Even though people think earthquakes only occur on the West Coast, they have and will occur in other parts of the United States.

Earthquakes In The Midwestern and Eastern United States?!

Most people think that earthquakes occur only in places like California, Alaska, and Japan. This couldn’t be further from the truth. Several major and numerous minor earthquakes have occurred in the midwestern and eastern United States, as well as eastern Canada. Some of the earthquakes that have caused notable damage in these areas are listed below.

• 1663 & 1870, St. Lawrence River region, Canada
• 1755, Boston/Cape Ann, Massachusetts. Earthquake estimated to be magnitude 6.0; buildings damaged.
• 1811 & 1812 – New Madrid, Missouri, experienced the three largest earthquakes known to have occurred in North America (magnitudes estimated between 7.2 and 8.3) and 203 damaging aftershocks. Soil liquefaction occurred.
• 1886, Charleston, South Carolina. Estimated magnitude 6.8. Soil liquefaction occurred. Extensive damage; 60 people or more died. Over 400 aftershocks over the next 30 years.
• 1895, Charleston, Missouri
• 1897, Giles County, Virginia
• 1884, New York City area
• 1931 — Valentine, Texas, had a magnitude 6.4 earthquake, the largest earthquake to hit Texas in historic times.
• 1935, Timiskaming, Ontario (Canada)
• 1947 — Michigan experienced a magnitude 4.4 earthquake.
• 1979 & 1980 – New York State and the adjacent areas experienced 131 earthquakes of magnitude 1 to 5.
• 1980, 5 earthquakes recorded north of Philadelphia, Pennsylvania.
• 1980, Kentucky shaken by a magnitude 5.1 earthquake.
• 1982 — New Brunswick, Canada, had a magnitude 5.7 earthquake.
• 1982 — Arkansas earthquake swarm starts. Eighty-eight earthquakes between June 24 and July 5, 1982. Four earthquakes with magnitudes of 4.0 to 4.5 during first 3 months of swarm. Total of about 40,000 earthquakes in the area (most very small or not felt) between 1982 and 1985.
• 1983 – Lake Charles, Louisiana, experienced a magnitude 3.8 earthquake.
• 1983 — Indiana had a magnitude 5.9 earthquake.
• 1986 — Painesville, Ohio, experienced a magnitude 4.9 earthquake and several aftershocks. The earthquake was felt in 11 states.
• 1987 — Southeastern Illinois experienced a magnitude 5.2 earthquake. This area has had 7 earthquakes of magnitude 4.5 or greater since 1892.

You probably noticed that in the list above, the magnitudes of earthquakes that took place in the 1800′s are described as “estimated.” This is because these earthquake events took place before the Richter magnitude scale was put in place. The approximation is made by a study of accounts of the earthquake which are correlated with the damage described in theMercalli intensity scale, which, as you may recall, allows a classification of an earthquake’s magnitude by ordinary people (not just seismologists). The descriptions may come even from personal correspondance of average citizens and include telling details about the damage the earthquake caused.

Over 900,000 earthquakes occur worldwide each year. Fortunately, the vast majority of them are magnitude 2.5 or less, and great earthquakes (magnitude 8.0 or more) only happen about once every 5 to 10 years. Most of these great quakes occur along the plate boundaries, not in the eastern and midwestern U.S.

A few areas of the midwestern and eastern United States are more prone to earthquakes than others. The most earthquake-prone areas include Charleston, South Carolina, eastern Massachusetts, the St. Lawrence River area, and the central Mississippi River Valley. Others sections of this part of the country are prone to earthquakes, but can expect fewer quakes of smaller magnitude. Below is a map showing the risk of damage by earthquakes for the continental United States.

FIGURE 1 (MODIFIED FROM STEARNS & MILLER, 1977)

The central Mississippi River Valley and the Charleston, South Carolina, are more prone to damage during earthquakes than the northern part of the country. These areas have sandy soils that shake more than solid rock, resulting in damage from subsidence during an earthquake. The high water tables along the Mississippi and near the coast also increase the risk of soil liquefaction during strong earthquakes.

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U.S. to upgrade volcano, earthquake monitoring

Fri Apr 10, 2009 7:31pm EDT

WASHINGTON, April 10 (Reuters) – Interior Secretary Ken Salazar said on Friday the U.S. government will spend $15.2 million to modernize equipment for monitoring U.S. volcanoes and improve warning systems.

The United States and its territories have 169 active volcanoes, and 54 of them need improved monitoring so scientists can warn the public about explosive disruptions, alert aircraft to ash clouds and inform communities of falling ash, lava and mud flows, Salazar said.

He pointed out that the March 22 eruption of the Mount Redoubt volcano, 106 miles (170 km) southwest of Anchorage, Alaska, showed the need for adequate monitoring.

When the Redoubt volcano erupted 19 years ago, a Boeing 747 passenger airliner flew into its ash cloud and nearly crashed.

The money to upgrade volcano monitoring will come from the $3 billion that the Interior Department is responsible for managing under the economic stimulus plan passed by Congress.

Salazar said $29.4 million will also be spent to double the number of seismic stations that monitor earthquakes across the country to 1,600. (Reporting by Tom Doggett; editing by Mohammad Zargham)