- THE FLORIDA EVERGLADES -
TV viewers around the world watched in horror last January as hundreds
of thousands of Africans fled rivers of fiery lava that spewed down the
slopes of Congo's Mount Nyiragongo and flooded the streets of Goma.
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- The vivid horror of that eruption, which killed about
75 people, was a stark reminder of the powerful"and often deadly"forces
that lie beneath the surface of Earth's majestic volcanoes.
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- Researchers have estimated that more than one billion
people"approximately 20 percent of the world's population"are
living in volcanic hazard zones.
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- Experts expect the number to rise. The rapid growth of
population, urbanization, and economic development are driving more and
more people to settle around volcanoes, significantly increasing the potential
loss of life and property in the event of eruptions, said Robert Tilling,
a senior volcanologist with the U.S. Geological Survey's Volcano Hazards
Program.
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- In this age of international air travel, even people
not living in the vicinity of a volcano are at risk, he noted.
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- "In the last 20 years there have been at least 80
encounters between airliners and ash clouds, causing hundreds of millions
of dollars in damage and lost revenue," said Tilling.
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- Every day, tens of thousands of passengers fly over volcanically
active regions such as the North Pacific, which has more than 100 active
volcanoes and four to five ash-producing eruptions each year.
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- A near-fatal accident in 1989 involving a 747 jetliner
alerted authorities to the increasing dangers of drifting clouds of volcanic
ash.
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- On December 15, 1989, a KLM flight carrying 231 passengers
flew into a cloud of ash that had erupted from Alaska's Redoubt volcano
and drifted 150 miles away. All four of the engines lost power and the
plane dropped nearly two miles in altitude before the crew could restart
the engines.
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- The plane sustained $80 million in damages. In 1995,
an international network of Volcanic Ash Advisory Centers was established
to counter the increasing threat.
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- Moving into Danger?
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- Figuring out how to reduce the hazards of volcanoes to
people and property is not an easy task.
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- Volcanologists and public officials agree that monitoring
is important, but it's expensive and not feasible for many countries. Emergency
planning is also costly and complicated, especially when it involves evacuating
huge numbers of people amid uncertain threats of volcanic eruption.
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- Despite major advances in technology in the last two
decades, the ability to predict when a volcano might erupt remains elusive.
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- But meeting the challenge is imperative because volcanoes
are "people magnets," said Christopher Small, a geophysicist
at Columbia University's Lamont-Doherty Earth Observatory. "If you
look at the settlement patterns in satellite imagery"and you can actually
see farms and towns"there are a surprising number of people living
in the throat of Satan," he said.
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- Small and a colleague conducted a study that combined
1990 census data and satellite imagery to determine how many people live
within volcanic hazard zones, or within 62 miles (100 kilometers) of a
volcano. They identified 457 volcanoes where one million or more people
live within that range. Many of the volcanoes"several in Indonesia
and Japan, for instance"have surrounding populations greatly exceeding
one million.
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- Part of the problem is greater competition for land and
an increase in urban migration that is swelling populations in previously
unsettled volcanic regions.
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- The ash emitted by volcanic eruptions is rich in nutrients,
making the soil highly fertile. "In tropical Java, people are farming
right on the flanks of volcanoes," said Small.
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- But the pattern is not confined to developing countries.
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- "Volcanoes and their surrounding environment are
beautiful places to live and work and recreate, and the number of people
moving into volcanic hazard zones is increasing in post-industrial as well
as developing countries," said C. Dan Miller, chief of the U.S. Geological
Survey's Volcano Disaster Assistance Program.
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- He cited southern Italy as an example. "Vesuvius
is perched right on the edge of Naples, and it has a 2,000-year history
of eruptions," said Miller, "yet there are 3.75 million people
living within 30 kilometers [18 miles] of the summit.
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- "What do they do if it starts erupting?" he
said. "No one can imagine evacuating a city the size of Naples."
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- Moving people out of hazard zones is generally not an
option, said Tilling. "Many of the land-use patterns are long established,
and people just won't do it," he said. "The only thing you can
do is have systematic volcano monitoring to detect the earliest departure
from normal activity."
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- Little Monitoring
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- The Smithsonian Institution's Global Volcanism Program
maintains a database with information about 1,500 volcanoes around the
world that have been active in the last 10,000 years"the blink of
an eye to geologists. At any given moment, nearly two dozen could be in
an eruptive phase, according to William Rose, a geologist at Michigan Technological
University.
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- Yet only about 20 volcanoes are adequately monitored,
and fewer than a third are monitored at all, according to the USGS.
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- Improved monitoring technology and greater scientific
understanding of how volcanoes operate are giving volcanologists and public
officials better tools to guide hazard-reduction planning, but evaluating
threats is frequently still a tough call.
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- "It could be weeks, months, or years from the time
a volcano shows some activity to eruption," said Miller. "It
may never erupt. Moving people out of the way for the big event in a timely
process is still our biggest challenge."
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- Mexico City knows the problem well. The city, which has
a population of more than 20 million, lies within 37 miles (60 kilometers)
of the summit of Popocatépetl, which has erupted at least 15 times
in the last 400 years.
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- The flanks and valleys surrounding "Popo" have
been evacuated several times since 1994 in response to earthquakes and
eruptions of volcanic ash and plumes of steam. Each time the mountain has
settled down without a major eruption, although sporadic activity continued
through 2001. Yet when, or if, a major eruption may occur next remains
unknown.
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- Challenge of Protection
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- The socio-economic costs of ordering an evacuation are
huge. People must be housed and fed, and the crowded conditions pose public
health risks. Security against major looting may be required, and commerce
grinds to a halt.
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- Scientists tracking active volcanoes walk a tightrope
when advising public officials on the likelihood of an eruption.
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- "The interface between the scientists monitoring
a volcano and public officials is very difficult," said Miller. "Most
people are willing to be evacuated once. But if nothing happens, the loss
of credibility could cause people to ignore future warnings."
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- Inadequate resources, poor coordination, and bureaucratic
inertia or a failure to heed warnings can have tragic consequences.
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- Colombia's Nevado del Ruiz began showing signs of volcanic
activity in November 1984. Volcanologists warned government officials that
the town of Armero lay directly in the path of what in the past had been
monumental mud flows. Yet no advance warning system or evacuation plans
were developed.
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- The volcano erupted on November 13, 1985. Two and a half
hours after the eruption began, a wall of mud, water, and debris burst
through the canyon above Armero, killing more than 23,000 people.
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- When Nyiragongo erupted early this year in the Democratic
Republic of the Congo, destroying 40 percent of the town, it was the volcano's
second major eruption in 25 years.
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- Scientists had warned government officials in January
that an eruption was imminent. But the war-torn government was unable to
respond to the warnings and no emergency preparations were in place. An
estimated 350,000 people fled to safety in neighboring Rwanda, where tens
of thousands remain in refugee camps.
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- "Scientists can't make the decision to evacuate,"
said Miller. "We can provide information on the hazards, and we are
working to do that. But using the information"long-range land-use
planning, development of early-warning systems, and evacuation plans"that's
up to public officials."
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- "The Heat is On!"airs
Sunday, June 16, 2 p.m. to 3 a.m. ET/PT
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- National Geographic Channel (United States) is heating
up on Father's Day (June 16) with a marathon of programming, featuring
nature's hottest elements. Topics range from fire fighting to volcanoes
to the hottest deserts.
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- Into the Fire"2 p.m. and 6 p.m. ET/PT"Get an
insider's look at the people who courageously race head-on into raging
infernos in the name of science and preservation. Journey to a remote South
Pacific island with two men as they brave one of nature's most violent
and spectacular forces"active volcanoes. Braving toxic gases, treacherous
rock falls, and giant pools of molten lava they risk it all to capture
scientific data and images and go into the fire.
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- Violent Volcano"3 p.m. ET/PT"In 1996, a volcano
destroyed the beautiful island of Montserrat. Now, we return to bring updated
reports on the condition of the island and the threat of another eruption.
The citizens that have yet to depart for safer ground watch, wait, and
pray that the volcano that lay dormant for 400 years will once again become
quiet so they can start their lives over again.
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- Volcano! Network Premiere"8 p.m. ET/PT"Explore
the youngest, most rapidly growing and possibly the most dangerous new
area of the Earth sciences. Rivaling the devastating power of atomic blasts,
volcanic eruptions have claimed more than 300,000 lives in the past 2,000
years. Recounting the horrific experiences of two volcanologists, Volcano!
documents some of the Earth's potentially dangerous volcanoes and the threat
they pose to the half a billion people who live within their shadow.
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- Volcano Hunters Network Premiere"9 p.m. ET/PT"Ever
wonder about the theory behind volcanic eruptions? Just what forces of
nature create the extraordinary blast of rock and lava that bursts from
the mouth of an active volcano? Join two volcano hunters as they get perilously
close to some of Earth's most dangerous active volcanoes, testing a new
theory on volcanic eruptions.
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- How Can They Kill? - Count the Ways
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- For most people, volcanoes evoke a classic image"looks
like a mountain, spouts like a fountain"and lava is the biggest threat.
But lava is fairly low on the list of the causes of death from volcanoes.
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- Mud flows, tidal waves, pyroclastic flows, catastrophic
landslides, and floods are often the most immediate threats. Pyroclastic
flows are superheated clouds of hot gases and ash that travel at speeds
of up to 125 miles (200 kilometers) an hour.
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- Mud flows can extend great distances. Mud flows from
the eruption of Cotopaxi in Ecuador in 1877 traveled more than 200 miles
(320 kilometers) down a valley at an average speed of 17 miles (27 kilometers)
an hour. Others have been clocked at more than 50 miles (85 kilometers)
an hour.
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- Forest fires are often sparked by lightning related to
a volcanic eruption.
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- Volcanoes can belch huge amounts of ash. Several people
who died on Mount St. Helens in 1980 suffocated from thick ash. The ash
can be so heavy that it causes the collapse of buildings, and when it combines
with moisture in the air, rain may fall as mud.
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- In August 1986, a supposedly extinct crater volcano in
Lake Nyos in Cameroon burped an invisible cloud of carbon dioxide. About
1,800 people in the surrounding region were asphyxiated by the deadly gas
as they were sleeping.
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- In 1918 the deadly eruption of Mount Tambora in Indonesia
spewed ash as far as 300 miles (480 kilometers) away. The explosion killed
10,000 and triggered global climate changes; snow fell in New England in
July 1816, known as the "year without a summer." It's been estimated
that 80,000 more people died as a result of famine related to crop losses.
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- When Indonesia's Krakatau"in the Sunda Strait between
Java and Sumatra"erupted in 1883, it caused a 100-foot-high (30-meter-high)
tsunami that killed 36,000 people.
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- A fast-moving cloud of hot gases killed 30,000 in Martinique
during the 1902 eruption of Pel.
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- About 10,000 people in Iceland"nearly 20 percent
of the country's population"died of starvation when Laki erupted in
1783, killing a large portion of the country's livestock.
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- Disease is also a threat. The 1902 eruption of Santa
Maria in Guatemala killed large numbers of birds, which increased the populations
of disease carriers such as flies, mosquitoes, and rats. An outbreak of
malaria killed more people (about 3,000) than the eruption itself.
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- Crowding related to evacuation can also promote the spread
of disease.
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- When Is a Volcano Active?
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- Designating a volcano as active, dormant, or extinct
is a somewhat contentious issue in the scientific community.
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- "There's no agreement on a standard definition of
an active volcano," said volcano expert Robert Tilling at the U.S.
Geological Survey.
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- The Smithsonian's Global Volcanism Program maintains
a database on more than 1,500 Holocene volcanoes"volcanoes that have
been active in the last 10,000 years.
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- "The Holocene, which goes back 10,000 years, is
a commonly used division in geological studies," said Tilling. "To
geologists, it's the blink of an eye, virtually the same as something happening
today."
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- A second criterion used to categorize volcanoes is "historically
active""those that have erupted and been documented by humans.
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- A wall painting in Central Turkey that dates from about
6200 B.C. shows the eruption of a nearby volcano. It's the earliest known
depiction of volcanic activity, according to the Smithsonian Institution.
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- More to see at nationalgeographic.com
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- © 2002 National Geographic Society. All rights reserved.
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