Transcript Volcanic Eruptions

Volcano
by
Paul Rega, M.D., F.A.C.E.P.
Since 1700
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Over 270,000 volcano-related deaths
have been recorded.
There have been 2-4 fatal eruptions
annually
The Ring of Fire
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80% of the world’s active volcanoes
are located around the Pacific Basin.
Where to find active volcanoes in
the U.S.
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Hawaii
Alaska
Pacific Northwest
Why be concerned about
volcanoes?
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In 1990, about 10% of the world’s
population lived within 100
kilometers of an active volcano.
Volcano
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Def.: A vent through which molten
rock has or may escape from the
earth’s surface.
Volcanic Eruption
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Def.: The ejection of gases and solid
material from a defect in the surface
of the Earth.
Magma
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Def.: Molten rock within the Earth.
• It is under pressure within the Earth.
• When it rises to the Earth’s surface, the
pressure decreases, allowing volatiles
and gases to escape.
Outgassing
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Def.: The release of volatiles
dissolved in magma.
Lava
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Def.: Molten rock that erupts at the
Earth’s surface.
• When magma exits the Earth, it become
lava.
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It’s slow and easily avoidable.
It’s responsible for very few
fatalities.
Pyroclastic Flows
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Def.: A mass of hot volcanic ash, lava fragments,
and gases that erupts from a volcano.
It moves rapidly, up to a few hundred mph.
It’s responsible for most volcanic deaths.
• Temperatures may reach to 900° C.
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Rocks and other debris within the flow may be
ejected from the flow causing a secondary blast
injury.
May extend for miles.
• The flow from the Mount St. Helens’ eruption reached 17
miles.
Tephra
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Def.: Solid fragments of magma and
volcanic rock that are ejected during
an eruption.
May cause significant blunt trauma
and burns.
Tephra accumulations may reach
several meters in depth.
Ash
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Def.: Tephra fragments that are
smaller than 2 mm.
Ash clouds are a potential health
hazard.
Lampilli
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Def.: Tephra fragments that are
between 2-64 mm in size.
Lava Bombs or Blocks
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Def.: Tephra fragments that are
greater than 64 mm in size.
May land several kilometers away
from a volcanic eruption.
Lahar
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Def.: Volcanic debris flows.
Ashfalls
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Increase in bronchial reactivity
During the Mount St. Helens’ eruption,
there was a doubling of asthma- and
bronchitis-related ER visits compared to
the previous year.
During ashfalls, total suspended particles
(TSP) in the air is a useful predictor or ER
visits for respiratory conditions.
• The number of ER visits for respiratory
complaints, especially asthmatics, during the
Mount St. Helens’ eruption was the highest
when the TSP concentration was greater than
30,000 µg/m .
Volcanic Gases
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Water vapor
Carbon dioxide: Threat
Sulfur dioxide: Threat
Hydrogen sulfide: Threat
Hydrogen
Carbon monoxide
Hydrogen fluoride: Threat
Helium
Sulfur dioxide
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Airways, eyes, and skin irritant
Produces acid rain
• Reacts with zinc on sheet metal roofs.
• Releases heavy metals into drinking
water.
Hydrogen fluoride
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Airways irritant
If ingested by animals may produce
fluorosis and death
Drinking water should be checked for
elevated fluoride levels.
Food should be cleaned of any ash to
avoid fluorosis.
Carbon dioxide
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Especially in low-lying areas, CO2 may
accumulate.
If the CO2 content of the air is greater
than 20-30%, asphyxiation may result.
Volcanoes can release gases even without
an eruption.
• 1984: In the volcanic Lake Monoun in
Cameroon, 73 people died from CO2 release
due to lake water turnover.
• 1986: A similar occurrence at Lake Nyos in
Cameroon. About 1700 people in a low-lying
area were killed by a massive release of CO2.
Hydrogen sulfide
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Because of its density, it may
concentrate in low-lying areas.
“Rotten egg” odor
Airway and eye irritant
• High concentrations may cause
pulmonary edema and death through
cellular asphyxiation.
Accompanying Catastrophes
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Earthquakes
Mudflows
Flash floods
Rock falls
Landslides
Acid rain
Fire
Tsunamis
Lightning strikes
Protective Measures
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If you live near an active volcano,
add to your disaster supply kit:
• Goggles
• Disposable breathing mask
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Best protection:
• Stay away from an active volcano site
If you are near a volcanic eruption
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Evacuate immediately
Avoid river valleys and low-lying
areas
• Caution with mudflows
• Look upstream before crossing a bridge
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Don’t cross if a mudflow is approaching
Mudflows are faster than you can run
Protection from falling ash
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Wear log-sleeved shirts and long pants
Wear goggles and eyeglasses
• Avoid contact lens
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Use a dust mask or place a damp cloth over
your face
Avoid being downwind and
Stay indoors unless there is concern the roof
may collapse from the accumulation of ash
on it
Close doors, windows, and all vents
Clear ash from roofs and rain gutters
Avoid running car engines to minimize
clogging engines
Reference
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Are You Ready?- Volcanoes.
www.fema.gov/areyouready/volcano
es.shtm. Accessed 5/19/06.
Jay G. Volcanic Eruption. In
Disaster Medicine, eds. Ciottone,
Darling, Anderson, et al. Mosby,
Philadelphia, PA. 2006.