Transcript Volcanoes - mrnicholsscience

Volcanoes
“Better put jam in your pockets, ‘cause
we’re toast”
--quote from a scientist running from
the 1991 Mt. Pinatubo eruption
The
Mercator
projection
The
Mercator
projection
• A projection of
the surface of a
sphere onto a
cylinder
The
Mercator
projection
• Consider a
small part of the
surface near the
equator
The
Mercator
projection
• The projection
The
Mercator
projection
• Consider a
small part of the
surface near the
North pole
The
Mercator
projection
The
Mercator
projection
• The projection
The
Mercator
projection
• The projection is
much larger for
polar regions!
The Mercator Projection Map
The Mercator Projection Map
Alaska isn’t
really as big
as it looks!
Where are the volcanoes?
Where are the volcanoes?
1) Mid-ocean ridges
Where are the volcanoes?
1) Mid-ocean ridges
--in the middle of oceans (duh.)
--North Pacific doesn’t have one.
Mid-Ocean Ridges
Where are the volcanoes?
1) Mid-ocean ridges
2) Edges of some continents
Where are the volcanoes?
1) Mid-ocean ridges
2) Edges of some continents
--Only one edge each
--Makes the Ring of Fire around the
North Pacific
Edges of continents
Ring of
Fire
Where are the volcanoes?
1) Mid-ocean ridges
2) Edges of some continents
3) Hot spots
Where are the volcanoes?
1) Mid-ocean ridges
2) Edges of some continents
3) Hot spots
--Hawaii, Yellowstone, Pitcairn Islands
Hot Spots
Hot Spots
Older
volcanoes
show the
plate has
moved over
the hot spot
Where are the volcanoes?
1) Mid-ocean ridges
2) Edges of some continents
3) Hot spots
4) Rifts
Where are the volcanoes?
1) Mid-ocean ridges
2) Edges of some continents
3) Hot spots
4) Rifts
--New Mexico, East Africa
Rifts
Where are the volcanoes?
Where are the volcanoes?
Where are the volcanoes?
Topographic Maps
Topographic Maps
• A topographic map has lines at certain
elevations
Topographic Maps
• A topographic map has lines at certain
elevations
--They make loops around hills, but never
cross. Downhill is at right angles to lines
--Lines close together indicate steep slopes
--Contour interval is the height difference
between two lines
--Relief is the difference from high to low on
the map
Topographic Maps
Steep slope—
closely spaced
lines
Topographic Maps
Gentle slope—
lines are not
closely spaced
Topographic Maps
Lines come
together at a
cliff
Lava flows downhill
• Magma contains:
Lava flows downhill
• Magma contains:
--Melted rock
--Dissolved gasses
Lava flows downhill
• Magma contains:
--Melted rock
--Dissolved gasses
How much
silica?
Lava flows downhill
• Magma contains:
--Melted rock
--Dissolved gasses
High silica=
high viscosity
Lava flows downhill
• Magma contains:
--Melted rock
--Dissolved gasses
High viscosity
= slow lava!
Lava flows downhill
• Magma contains:
--Melted rock
--Dissolved gasses
Lots of gas=
lots of pressure
Lava flows downhill
• Magma contains:
--Melted rock
--Dissolved gasses
Lots of pressure 
pyroclastic flows
Lava flows downhill
• Magma contains:
--Melted rock
--Dissolved gasses
Lots of pressure 
pyroclastic flows
“hot”
“chunks”
Lava flows downhill
• Magma contains:
--Melted rock
--Dissolved gasses
Lahars might be even more dangerous—
mudflows from melted snow on the volcano
Everything flows downhill
• Q: How far will it go?
Everything flows downhill
• Q: How far will it go?
• A: It depends…
Everything flows downhill
• Q: How far will it go?
• A: It depends…
– Volume of material
– Viscosity
– Type of flow
– Slope
– Surface features
What can you do about it?
What can you do about it?
1) Be somewhere else.
What can you do about it?
1) Be somewhere else.
2) Maybe, if it’s a small flow…
What can you do about it?
1) Be somewhere else.
2) Maybe, if it’s a small flow
a.
b.
c.
d.
Fireproof roofs—in case of pyroclastics
Cool lava with fire hoses to solidify it
Barriers could turn it aside
Drainage channels to channel it around
structure
Airborne Hazards
• How much gets tossed into the air?
• What gets tossed?
• How hard is it tossed?
How much gets tossed into the air?
• Measure the volume in cubic kilometers!
(km3)
How much gets tossed into the air?
• There is a huge variation in volume
•
•
•
•
Small: up to 1 km3
Medium: up to 10 km3
Large: up to 100 km3
Gigantic: hundreds of km3
What gets tossed?
Sizes of particles
• Tephra—general term for airborne pieces
• Volcanic bombs
• Lapilli
• Ash
What gets tossed?
Sizes of particles
• Tephra—general term for airborne pieces
• Volcanic bombs—largest chunks (>fist-sized)
• Lapilli—smaller chunks
• Ash—smallest particles (< 2mm, dust-sized)
What gets tossed?
Distance
• Different sizes of particles go different
distances
• The smaller the particle, the farther it goes
Volcanic bombs < Lapilli < Ash
What gets tossed?
Damage
Volcanic bombs—dangerous only if it hits you.
Lapilli—dangerous only if it hits you
Ash—damages lungs, motors, smooth
surfaces, forms lahars
How hard is it tossed?
• Measured against the
VEI
—the Volcanic Explosivity Index
How hard is it tossed?
• Measured against the
VEI
—the Volcanic Explosivity Index
Ranges from:
0 (mild) to 7 (We’re all going to die!)
How hard is it tossed?
VEI is related to volume
•
•
•
•
Volume
Small: up to 1 km3
Medium: up to 10 km3
Large: up to 100 km3
Gigantic: hundreds of km3
VEI
0-4
5
6
7
How hard is it tossed?
VEI is related to the type of
magma
The higher the silica and dissolved gasses,
the higher the VEI
How many are killed?
• How much gets tossed into the air?
• What gets tossed?
• How hard is it tossed?
• How many people live in the
path of the flows and airborne
debris?
Volcanoes and the atmosphere
A volcanic eruption produces:
Volcanoes and the atmosphere
A volcanic eruption produces:
a.
b.
c.
Volcanoes and the atmosphere
A volcanic eruption produces:
a. Flows
b. Airborne debris
c. Gasses
August 21, 1986
• Lake Nyos, Cameroon—a crater lake.
• Carbon dioxide released by the volcano
builds up in the waters
• When released, it flows down the hillside
and smothers 1700 people
Gasses from volcanoes
•
•
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•
•
Water vapor
Carbon dioxide
Hydrogen chloride
Nitrogen
Sulfur dioxide
Gasses from volcanoes
Normal
components
of our
atmosphere
•
•
•
•
•
Water vapor
Carbon dioxide
Hydrogen chloride
Nitrogen
Sulfur dioxide
Gasses from volcanoes
•
•
•
•
•
Water vapor
Carbon dioxide
Hydrogen chloride
Nitrogen
Contribute to
Sulfur dioxide
acid rain
Gasses from volcanoes
Contributes
to global
warming
•
•
•
•
•
Water vapor
Carbon dioxide
Hydrogen chloride
Nitrogen
Sulfur dioxide
Gasses from volcanoes
•
•
•
•
•
Water vapor
Carbon dioxide
Hydrogen chloride
Nitrogen
Contributes
Sulfur dioxide
to global
cooling
Gasses from volcanoes
•
•
•
•
•
Warming?
Water vapor
Carbon dioxide
Hydrogen chloride
Nitrogen
Sulfur dioxide
Cooling?
Volcanic activity cools the Earth
Three ways:
•
•
•
Volcanic activity cools the Earth
Three ways:
• Sulfur dioxide
•
Ash
•
Water vapor
Volcanic activity cools the Earth
Three ways:
• Sulfur dioxide —forms tiny droplets of
sulfuric acid in the upper atmosphere that
reflect sunlight back to space
• Ash
•
Water vapor
Volcanic activity cools the Earth
Three ways:
• Sulfur dioxide —forms tiny droplets of
sulfuric acid in the upper atmosphere that
reflect sunlight back to space
• Ash—(same effect in upper atmosphere)
•
Water vapor
Volcanic activity cools the Earth
Three ways:
• Sulfur dioxide —forms tiny droplets of
sulfuric acid in the upper atmosphere that
reflect sunlight back to space
• Ash—(same effect in upper atmosphere)
•
Water vapor —forms clouds in lower
atmosphere that reflect sunlight back to
space
The year without a summer
• 1815; following the Tambora eruption
• Lakes in Pennsylvania froze over in July.
Tungurahua NZ
Arenal CR
Fourpeaked AK
Mayon, Phillipines
Mayon, Phillipines
Monitoring Volcanoes
• Did you ever get the feeling you are about
to make a big mistake?
Monitoring Volcanoes
• Did you ever get the feeling you are about
to make a big mistake?
• Pay attention to that feeling.
Monitoring Volcanoes
It hurts to admit when you make
mistakes - but when they're big enough,
the pain only lasts a second.
• Did you ever get the feeling you are about
to make a big mistake? It could be that
Just because you've
the purpose of
always done it that
your life is only
• Pay attention to that feeling.
way doesn't mean it's
to serve as a
not incredibly stupid.
warning to
others
Monitoring Volcanoes
Define:
Vulcanology
Seismology
Monitoring Volcanoes
Define:
Vulcanology—the study of volcanoes
Seismology—the study of earthquakes
Monitoring Volcanoes
Q: Why bother?
Monitoring Volcanoes
Q: Why bother?
A: To tell people when to run away!
Monitoring Volcanoes
Q: Why bother?
A: To tell people when to run away!
It is easier to save people
than property.
Monitoring Volcanoes
Q: Why bother?
A: To tell people when to run away!
It is easier to save people
than property.
You can move vehicles and carry
valuables, but don’t let the delay kill you.
Monitoring Volcanoes
Think about a volcanic eruption.
What is happening?
Monitoring Volcanoes
Think about a volcanic eruption.
Magma from below is forced up, releasing
lava, gasses and airborne debris.
Monitoring Volcanoes
•
1)
2)
3)
4)
The changes that might occur before an
eruption might include:
Monitoring Volcanoes
•
1)
2)
3)
4)
The changes that might occur before an
eruption might include:
Swelling of ground surface
Gasses released
Minor earthquake activity
Change in local electrical and magnetic
fields
Monitoring Volcanoes
•
1)
2)
3)
4)
The changes that might occur before an
eruption might include:
Swelling of ground surface
Gasses released
Minor earthquake activity
Change in local electrical and magnetic
fields
If you see excess heat produced,
you might be too late
Monitoring Volcanoes
•
1)
2)
3)
4)
The changes that might occur before an
eruption might include:
Swelling of ground surface
Gasses released
Minor earthquake activity
Change in local electrical and magnetic
fields
Any of these changes can be measured
and used to predict eruptions
Monitoring Volcanoes
Some of the equipment includes:
• Clinometers
• Seismometers
• GPS systems
• Gas samplers
Monitoring Volcanoes
Some of the equipment includes:
• Clinometers measure changes in slope.
• Seismometers measure tremors
• GPS systems measure changes in altitude
• Gas samplers sample gasses. Duh.
Monitoring Volcanoes
•
It is expensive.
•
Only about ¼ of the world’s volcanoes
have any monitoring at all.
USGS (US Geological Survey) and
HVO (Hawaiian Volcano Observatory)
--are the best in the world at vulcanology
Monitoring Volcanoes
Steve Zipprich
Denver South High School
Class of 2004
Attended UC Santa Clara to study vulcanology