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 flowa. Fireproof roofs—in case of pyroclastics

b. Cool lava with fire hoses to solidify it

c. Barriers could turn it aside

d. 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?

DamageVolcanic 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 volumeVolume VEI

• Small: up to 1 km3 0-4

• Medium: up to 10 km3 5

• Large: up to 100 km3 6

• Gigantic: hundreds of km3 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

• Water vapor

• Carbon dioxide

• Hydrogen chloride

• Nitrogen

• Sulfur dioxide

Gasses from volcanoes

• Water vapor

• Carbon dioxide

• Hydrogen chloride

• Nitrogen

• Sulfur dioxide

Normal components

of our atmosphere

Gasses from volcanoes

• Water vapor

• Carbon dioxide

• Hydrogen chloride

• Nitrogen

• Sulfur dioxideContribute to

acid rain

Gasses from volcanoes

• Water vapor

• Carbon dioxide

• Hydrogen chloride

• Nitrogen

• Sulfur dioxide

Contributes to global warming

Gasses from volcanoes

• Water vapor

• Carbon dioxide

• Hydrogen chloride

• Nitrogen

• Sulfur dioxideContributes

to global cooling

Gasses from volcanoes

• Water vapor

• Carbon dioxide

• Hydrogen chloride

• Nitrogen

• Sulfur dioxide

Cooling?Warming?

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

• Did you ever get the feeling you are about to make a big mistake?

• Pay attention to that feeling.

It could be that the purpose of your life is only to serve as a

warning to others

It hurts to admit when you make mistakes - but when they're big enough,

the pain only lasts a second.

Just because you've always done it that

way doesn't mean it's not incredibly stupid.

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

• The changes that might occur before an eruption might include:

1)

2)

3)

4)

Monitoring Volcanoes

• The changes that might occur before an eruption might include:

1) Swelling of ground surface

2) Gasses released

3) Minor earthquake activity

4) Change in local electrical and magnetic fields

Monitoring Volcanoes

• The changes that might occur before an eruption might include:

1) Swelling of ground surface

2) Gasses released

3) Minor earthquake activity

4) Change in local electrical and magnetic fields

If you see excess heat produced, you might be too late

Monitoring Volcanoes

• The changes that might occur before an eruption might include:

1) Swelling of ground surface

2) Gasses released

3) Minor earthquake activity

4) 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 ZipprichDenver South High School

Class of 2004

Attended UC Santa Clara to study vulcanology