This week began with plans for a nationwide earthquake drill. But residents in Maine got a taste of the real thing.
Bob
Marvinney, Maine's state geologist, said he was sitting on his couch at
home at 7:12 p.m. Tuesday, when the magnitude-4.0 quake hit. The
shaking started 4 miles beneath the Earth, near Hollis Center in
southwestern Maine, and resulted in no reports of damage or injuries,
according to the U.S. Geological Survey (USGS).
"I felt a rumbling
start, it started pretty gradual, and then it got to the strongest
point" and lasted about a half-minute, Marvinney said. "I knew right
away it had to be an earthquake."
Though earthquakes on the East
Coast have destroyed buildings and caused fatalities, they are usually
smaller and far less frequent and therefore harder to predict than West
Coast quakes, experts say. They behave differently because the Earth and
rocks in the East are older, colder and denser than in the West,
causing the shock waves from Eastern earthquakes to be felt much further
away.
Tuesday's rumble came as emergency planners, school
officials and building managers prepared for the Great Shakeout, which
for the first time will include Georgia, South Carolina, North Carolina,
Virginia, Maryland and the District of Columbia. Across the country and
around the world, more than 13 million people have registered at
Shakeout.org to participate, according to USGS.
The drill happens
on the third Thursday of October, and to illustrate that earthquakes
are random, the time is always the same as the date, this year: 10:18 on
10/18. Southeastern states wanted to join the drill last year, but
there wasn't time for publicity less than two months after a quake Aug.
23, says Brian Blake, earthquake program coordinator with the Central
U.S. Earthquake Consortium, which organizes the drill.
Earth
scientists say the preparations are necessary because, despite their
rarity, major earthquakes do happen on the East Coast, and they can be
dangerous because people and structures are not prepared.
Maine is
near one of the more active earthquake zones on the East Coast,
according to the USGS. The state shook from 16 quakes of magnitude 3.5
or greater during a 30-year period from 1974 to 2003, ranking 20th among
all states for the highest number of earthquakes.
Tuesday's
shaking was a "thrust earthquake," the result of an up-and-down rupture
below the Earth, said Rob Williams, who coordinates the Central and
Eastern U.S. Earthquake Program for the USGS. One side of the fault
moved a foot or two relative to the other 4 miles down, which is rather
typical for the area, he says.
Two previous significant
earthquakes have shaken the area: in 1904, when a magnitude-5.1 quake
hit in the area of Calais and Eastport, and in 2006, when a
magnitude-3.8 one hit central Maine.
When a magnitude-5.8
earthquake shook the USGS headquarters in Virginia last year, facility
managers at the government's science branch weren't sure what to do.
Like
most of their counterparts in school districts, sheriff's offices and
businesses across the Southeast, "earthquake wasn't an entry in their
notebook" of emergency plans, says geophysicist Mike Blanpied, associate
coordinator of the USGS Hazards Program.
As a result, many people
across the Southeast did the wrong thing, Blanpied says. Some stayed in
place. Others ran outside as the ground continued to roll. Downtown
Washington shut down after the quake, resulting in massive traffic jams
that lasted hours.
"That one last year was just a little taste of
what's coming in the near future," says Martin Chapman, a geophysicist
at Virginia Tech University. "There's a significant probability that a
young child will experience significant shaking from an earthquake if
they stay in the eastern South during his or her lifetime."
Most
people's natural reaction - run outside - is one of the most dangerous,
Chapman says. "That exposes you to things, cornices and chimney tops,
falling down," he says. "People get killed trying to run out of
buildings."
When the earth starts shaking, people should
immediately "drop, cover and hold on," meaning hit the floor, crawl
under a desk or table and hold on to something until the shaking stops,
according to the USGS and other national emergency response
organizations. (The only exception: people in adobe buildings should
take cover in a doorway or run outside.)
The geological record shows that severe earthquakes of magnitude 7.0
or greater happen on average every 500 to 1,000 years on the East Coast.
The strongest East Coast earthquake on record was one of magnitude 7.3
on Aug. 31, 1886, that killed 60 people and caused heavy damage in
Charleston, S.C., and nearly destroyed the nearby town of Summerville.
It was felt as far away as Chicago.
If such an earthquake hit a
much more densely populated Charleston today, it would cause a lot more
damage and injury, said Derrec Becker, spokesman for the South Carolina
Emergency Management Division.
Damage still exists from the quake
in 1886, so there would be liquefaction of the ground and, according to
emergency planners' estimates, 900 fatalities, 45,000 injuries and
hundreds of schools, firehouses and bridges destroyed. The damage toll
would reach $250 billion for the East Coast, according to a 2005 study
by the South Carolina Emergency Management Division.
"It would be
the largest natural disaster South Carolina had ever experienced,"
Becker said. "We know significant earthquakes have occurred in the past,
and it's not a matter of if but when."
West Coast quakes occur on
the boundaries of tectonic plates, where the North American plate is
moving south relative to the Pacific plate, which is diving under the
North American plate. East Coast quakes release pressure through ancient
fault lines in the middle of the North American plate for sometimes
mysterious reasons, Williams said.East Coast earthquakes are caused for
reasons that are totally different than on the West Coast, and in much
older rocks, which makes it harder to predict where they are likely to
happen, Williams says.
Some of those pressures may be the release
of loads created during the last ice age, 20,000 to 30,000 years ago, as
the Earth bounces back from under the now-missing weight of ice
thousands of feet thick. Those stresses are released through the Earth's
crust, which is scarred by the remnants of billions of years of
tectonic plate action. Geologists have mapped such faults all across the
Eastern USA, Williams said.
"Most of the time, these faults are
ancient features of the Earth's crust from the time when the Eastern
U.S. was near a plate boundary, in Pangea, the last time all the plates
were together, about 200 million years ago," Williams said. " We see a
lot of faults, but it's hard to determine which ones are active and
which ones will become active."
Becker says predicting when an earthquake will occur is not possible, but preparation can save lives.
In
Charleston on the day of the drill, College of Charleston earthquake
experts will lead lectures and walking tours of damage from the
earthquake in 1886.
Thursday,
20 to 30 students from Holly Hill Elementary School in Orangeburg
County will practice "drop, cover and hold on" at the South Carolina
State Museum in Columbia. The drill will be live-streamed on the
Emergency Management Division's website, Becker said.
In Louisa
County, Va., 4,700 students will practice the drill, as they have
regularly since last year's quake destroyed two schools and displaced
40% of the student body. The handful of injuries there were all caused
by falling objects, such as televisions, says Douglas Straley, assistant
superintendent of Louisa County Public Schools.
"Last summer, it caught us all by surprise," Straley said.
Some
teachers didn't realize until the shaking was almost over that an
earthquake was in process, and most didn't know what to do. Then they
had to guide students outside - and in some cases carry them - across
partially collapsed buildings and ceilings that covered the floors, he
said. Thousands of students finished the school year sharing a middle
school and in modular buildings.
"The uneasiness continues because
we continue to still get aftershocks," Straley said. "We had one a
couple weeks ago. It's that reminder, not like a tornado that comes and
is gone. Its continuous aftershocks is a continuous reminder that it can
happen again."
Closer to Washington, USGS Director Marcia McNutt
will join students at Langston Hughes Middle School in Reston as they
practice the drill.
Montgomery College in Rockville, Md., will use
the date as a multiphase emergency exercise, said Steve
Maloney,director of emergency planning.
Maloney's department has been sending e-mail and text messages about
earthquake preparedness and how to prepare for emergencies at home for
weeks leading up to today's drill.
"If they're not prepared at home, they won't come to school or work, so we want them to be prepared," he said.
On
the day of the drill, security staff will assess all the buildings and
practice evacuating one where earthquake "damage" has occurred, he said.
Despite
taking the drill seriously, Maloney said he views the chances of an
earthquake as pretty low, but the drill is a good excuse to get people
to think about emergencies.
"I think it's unlikely we'll have
another big one," he said. "For us, consequences for earthquakes are not
that high. We worry a lot more about weather events."
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