Volcanoes Notes
GLCEs Met
E1.2E
Evaluate the future career and occupational prospects of science fields.
E2.1B
Analyze the interactions between the major systems (geosphere, atmosphere,
hydrosphere, biosphere) that make up the Earth.
E2.3A
Explain how carbon exists in different forms such as limestone (rock), carbon
dioxide (gas), carbonic acid (water), and animals (life) with Earth systems and
how those forms can be beneficial or harmful to humans.
E2.3d
Explain how carbon moves through the Earth system (including the geosphere)
and how it may benefit (e.g. improve soils for agriculture) or harm (e.g. act as a
pollutant) society.
E3.1B
Explain the relationship between the rock cycle and plate tectonics theory in
regard to the origins of igneous, sedimentary, and metamorphic rocks.
E3.p3B
Describe the three types of plate boundaries (divergent, convergent, and
transform) and geographic features associated with them (e.g., continental rifts
and mid-ocean ridges, volcanic and island arcs, deep-sea trenches, transform
faults).
E3.p3C
Describe the three major types of volcanoes (shield volcano, stratovolcano, and
cindercones) and their relationship to the Ring of Fire.
E3.3A
Explain how plate tectonics accounts for the features and processes (sea floor
spreading, mid-ocean ridges, subduction zones, earthquakes and volcanoes,
mountain ranges) that occur on or near the Earth’s surface.
E3.3C
Describe the motion history of geologic features (e.g., plates, Hawaii) using
equations relating rate, time and distance.
E3.4A
Use the distribution of volcanoes to locate and determine the types of plate
boundaries.
E3.4B
Describe how the sizes of volcanoes are measured or characterized.
E3.4C
Describe the effects of volcanic eruptions on humans.
E3.4d
Explain how the chemical composition of magmas relates to plate tectonics and
affects the geometry, structure, and explosivity of volcanoes.
E3.4e
Explain how volcanoes change the atmosphere, hydrosphere, and other Earth
systems.
- Volcanoes are (mostly) a constructive force (because they build up the earth)
- Volcanoes make up part of the geosphere
- Most U.S. volcanoes are located along the west coast (AK, AZ, HI, ID, NM, OR, SD, UT, WA,
WY)
How Volcanoes Affect Earth Systems (E2.1B) (E3.4e)
When volcanoes erupt, they emit gases (like CO2) into atmosphere. This is just another example
of interacting earth systems (geosphere and atmosphere). (E3.4e)
Volcanic eruptions (geosphere) can affect life (biosphere) by emitting heat,
smothering/suffocating ash and debris, and harmful gases. (E3.4e)
Some volcanic areas heat nearby lakes, warming the water. This demonstrates an interaction
between the geosphere and the hydrosphere. (E3.4e)
Volcanoes can release gases (carbon dioxide and sulfur dioxide) and particulate matter (dust and
ash) which can pollute the air (atmosphere), pollute nearby lakes (hydrosphere), and harm living
things (biosphere). (E3.4e)
Sulfur Dioxide turns into acid rain, which negatively affects the hydrosphere
Also produces carbon monoxide, fluorine, chlorine, hydrogen, and nitrogen
When volcanic material (geosphere) combines with water (hydrosphere), mudslides can form,
which can damage living things (biosphere). (E3.4e)
Magma
How Magma Forms
Slushy mix of molten rock, mineral grains, and gases beneath earth’s surface
Most rocks melt at temperatures between 800° C and 1200° C.
Factors affecting melting temperature of rock
A. Pressure- as depth (and pressure) increases, melting temperature increases
B. Water- the more water a rock has in its pores, the easier it is to melt (melting
temperature is lower than rocks with less or no water in its pores). If a rock has a lot of
water in it AND it’s found at a deep part of the earth’s interior, it has a lower melting
point.
When magma/lava cools and hardens, it forms igneous rock. (E3.1B)
Types of Magma (E4.3d)
Magma Composition
Viscosity- a fluid’s internal resistance to flow (is it runny or syrup-like)
EX: motor oil is “thick” and has a high viscosity, whereas water is “thin” and has a low
viscosity.
- the hotter the material, the lower the viscosity
- the higher the silica content, the higher the viscosity
3 types of Magma- Basaltic, Andesitic, Rhyolitic
1. Basaltic
- forms when rocks in upper mantle melt
- low silica content (mafic)
- low viscosity
- quiet eruptions
- Shield Volcanoes
2. Andesitic
- found where oceanic crust is subducted below continental crust into the mantle
- intermediate viscosity
- intermediate eruptions
- Cinder-Cone Volcanoes
3. Rhyolitic
- forms when molten material mixes with overlying silica-rich and water-rich
continental crust
- high silica content (felsic)
- high viscosity
- explosive eruptions
- Stratovolcanoes (Composite Volcanoes)
Three types of Volcanoes (E3.p3C) (E4.3B) (E3.4d)
The higher the viscosity (thicker it is), the more silica, the more gases a volcano has = MORE
VIOLENT eruption! (E3.4d)
1. Shield Volcano- least dangerous
- Broad, gently sloping sides formed from accumulation of layers of basaltic lava flows
(resembles a shield)
- quiet (non-explosive) eruptions
- low viscosity, low silica (mafic), few amount of gases
- basaltic composition
- generally occur at Mid-Ocean Ridges (divergent boundaries)
- EX: Hawaiian Islands (Mauna Kea), Oregon, Northern California
2. Cinder Cone Volcano
- small (not that tall)- less than 1600 feet tall
- steep slopes form from ash and cinders are ejected high in the air and fall back down to
pile up.
- can look like a big ant hill
- mildly violent, fairly explosive (intermediate) eruptions
- moderate viscosity, moderate silica, moderate amount of gases
- andesitic composition
- generally occur only above subduction zones (convergent boundaries)
- EX: Izalco volcano (El Salvador); Paricutin volcano (Mexico), western North America
(Mount Shasta- CA)
3. Stratovolcano (or Composite)- MOST DANGEROUS
- Tall, with mixed layers of ash/cinders and lava
- Violent eruptions
- High viscosity, high silica, high amount of gases
- rhyolitic composition
- EX: Mt. St. Helens (Washington- USA); Mt. Rainier and Mt. St. Helens (Washington);
Mt. Pinatubo; Mt. Fuji (Japan), Mount Cotopaxi (Ecuador), Mount Shasta (California),
Mount Hood (Oregon), Mount St. Helens and Mount Rainier in Washington
Ring of Fire
- Volcanic belt (or ring) of that ranges along the outside of the Pacific Plate
- Volcanoes occur here because they mark the boundary between the Pacific Plate and
various other tectonic plates. The earth’s crust is either weak or there is a gap for magma
to rise to the surface.
- Mostly composed of Stratovolcanoes (Composite) and Cinder-Cone Volcanoes
- Shield Volcanoes are found in middle of tectonic plate
- Mostly convergent volcanism
- Serves as solid evidence for theory of plate tectonics
Distribution of volcanoes and Plate Boundaries (E3.4A) (E3.p3B)
Earth’s Active Volcanoes (pg. 473 of Glencoe), cross-referencing with pg. 43 of Inside Earth
Book or pg. 455 of Glencoe book
Most volcanoes occur in similar areas (where crust is weak and fractured)
- Along plate boundaries (or along the coast of a continent)
- Middle of the ocean (islands)
Convergent Volcanism- accounts for 80% of all volcanoes
Plates come together, denser once subducts (sinks) below the other and turns into magma.
That “excess magma” is then forced to the surface to form volcanoes.
Island Volcanoes (aka Island Arcs) occur because of oceanic-oceanic convergent
collisions. (E3.p3B)
EX: Mariana Islands (western Pacific Ocean)
EX: Lesser Antilles (western Atlantic Ocean)
Continental Volcanoes occur because of oceanic-continental convergent collisions.
Mt. St. Helens (Washington, USA)- Convergent (Continental Volcano)- Juan de Fuca
plate subducting below North American Plate
Paricutin (Mexico)- Convergent (Continental Volcano)- Pacfic Plate subducting below
North American Plate
Mt. Fuji- Convergent- Pacific Plate subducting below the Eurasian Plate
Pinatubo- Convergent- Philippine Plate subducting below the Eurasian Plate
Krakatau- Convergent- Indo-Australian Plate subducting below Eurasian Plate
Tambora- Convergent- Indo-Australian Plate subducting below Eurasian Plate
Vesuvius- Convergent- African Plate subducting below Eurasian Plate
Etna- Convergent- African Plate subducting below Eurasian Plate
Pelee- Convergent- South American Plate subducting below Caribbean Plate
Nevado del Ruiz (South America)- Convergent (Continental Volcano)- Nazca Plate
subducting below South American Plate
Mariana Islands- Convergent- Pacific Plate subducting below Philippine Plate
** Also included, but not on pg. 455 of Glencoe Book- Japan, New Zealand,
Indonesia, the Caribbean Islands, the Philippines, and the Aleutians.
Divergent Volcanism- accounts for 15% of all volcanoes
Plates move apart, magma rises and fills the gap created by divergence- called rift zones.
This type of volcanism occurs along mid-ocean ridges.
Only a few places (Iceland and Azores Island in the Atlantic Ocean) do these volcanoes
rise above sea-level. Most are below water. (Mid-Ocean Ridge)
Hekla (Iceland)- Divergent- where Eurasian and North American plates are splitting
apart
Surtsey (Iceland)- Divergent- where Eurasian and North American plates are splitting
apart
Kilimanjaro (Africa)- Divergent- part of African Plate splitting apart
Deception Island- Divergent- Antarctic Plate splitting apart
Hot Spot Volcanism- accounts for 5% of all volcanoes
Areas of high temperatures in the mantle
Magma rises to the surface vertically, to form volcanoes
Provides evidence of plate movement
Can tell rate and direction of movement by tracking the positions of these
volcanoes (E3.3C)
Kilauea (Hawaii)- Hot Spot (Oceanic Volcano)- Exceptionally hot magma rises up
through the Pacific Plate to form an island
Mauna Loa (Hawaii)- Hot Spot (Oceanic Volcano)- Exceptionally hot magma rises up
through the Pacific Plate to form an island
Yellowstone Park (WY)- (Continental Volcano)- Exceptionally hot magma rises up
through the North American Plate to form volcano. Last erupted 75,000 years ago.
Galapagos Islands (west of South America)- Hot Spot (Oceanic Volcano)- Exceptionally
hot magma rises up through the Pacific Plate to form an island
Mount Unzen (Japan)- Hot Spot (Oceanic Volcano)- Exceptionally hot magma rises up
through the Pacific Plate to form an island
Easter Island (west of South America)- Hot Spot (Oceanic Volcano)- Exceptionally hot
magma rises up through the Pacific Plate to form an island
How volcanoes are measured or characterized (E3.4B)
(Also includes types of Volcanoes- characterized as strato, cinder cone, or shield)
How to detect/predict volcanic activity
More successful in predicting volcanoes than earthquakes.
What they look for:
Changes in surface features and elevation (using laser tiltmeters)
Changes in magnetic field (like occurs during sea-floor spreading)
Changes in the water level or water condition of a volcano’s crater lake
pH, amount of water, temperature, etc.
Changes in seismic activity (small earthquakes that occur before eruption)
Damage measure or classified in terms of:
Monetary damage
Lives lost
Volume of lava, ash, or dust
How volcanologists characterize volcanoes (E3.4B)
Volcanic Explosivity Index (VEI)
- Measure volume of ejected material (tephra), height of eruption cloud, and other
qualitative observations
- open-ended range from 0 (non-explosive) to 8 (largest recorded volcano in history)
-each number on the scale represents a blast ten times bigger than the previous. So
a 1 on the VEI is ten times more explosive than a 0; a 2 is ten times bigger than a
1 and 100 times bigger than a 0; a three is ten times bigger than a 2, 100 times
bigger than a 1 and 1000 times bigger than a zero, etc.
Effects of Volcanic Eruptions on Humans (E3.4C) (E2.3d)
The Bad
Ash can get into their lungs and cause respiratory (breathing) problems or coat the lungs causing
them to suffocate
Ash can get into car/plane engines, causing them to stall or not run properly
Ash can land on top of roofs and if it gets wet, can cause roofs to collapse
Ash can damage crops (for farmers), which might make food a bit scarce
Ash can pollute the air, scatter and block out the sun’s rays, thus altering the earth’s temperature
(E2.3d)
Ash and dust in the air collects water and causes thunderstorms
Ash and gases can raise the acidity of the lakes and waters in surrounding area
Gases (carbon dioxide and sulfur dioxide) can cause acid rain
Lava can heat and/or burn and even bury things in its path
Hot, destructive ash, cinders (pebble sized), or bombs (golf-ball to car-sized) can cause physical
damage to people, cars, buildings, crops, etc.
Called a pyroclastic flow- very fast- hard to outrun
Can cause landslides, mudslides and/or avalanches
Can cause tsunamis
Can cause people to have to evacuate and move from their homes, work
The Good
Volcanic ash and hardened lava break down to form nutrient-rich soil (E2.3d)
- Releases potassium, phosphorus, and other materials plants need for growth
New land is formed
Geothermal Energy- heat energy from the earth
- some hot water from geothermal springs is pumped directly into houses
- can be used for electricity
- hot water is pumped into turbines  steam spins a wheel (convection) 
spinning wheel turns a generator that converts energy into electricity
Fascination and spectacular scenery attracts tourism (which brings in money for the local
economy)
Historic Eruptions
1883- Krakatau (Indonesia)
1902- Mt. Pelee (Island of Martinique, Caribbean)
1912- Mt.Katmai (Alaska, USA)
1980- Mt. St. Helens (Washington, USA)
1991- Mt. Pinatubo (Philippines)
1995- Soufriere Hills (Island of Montserrat, Caribbean)
Careers working with Volcanoes (E2.1E)
Volcanologist
http://volcano.und.edu/vwdocs/how_to.html
http://vulcan.wr.usgs.gov/Outreach/StudyVolcanoes/framework.html
http://sciencecareers.sciencemag.org/career_development/previous_issues/articles/3500/a
_volcanologist_s_vista
Links
Volcanoes- General
Your Planet Earth- contains ppt on Volcanoes
http://www.earth4567.com
Volcano World
http://volcano.und.nodak.edu/
How Volcanoes Work
http://www.geology.sdsu.edu/how_volcanoes_work/index.html
Volcanoes- by Robert Tilling
http://pubs.usgs.gov/gip/volc/text.html#types
USGS Volcano Hazards Program
http://volcanoes.usgs.gov/index.html
Can We Prevent Volcanoes
http://www.learner.org/exhibits/volcanoes/
NOVA- Volcano’s Deadly Warning
http://www.pbs.org/wgbh/nova/volcano/
Volcanoes of the United States
http://pubs.usgs.gov/gip/volcus/
Volcano Animations
http://www.westhamptonbeach.k12.ny.us/teachers/cohen/sciweb/earthscience/Volcanoes/volcano_movies.htm
http://news.bbc.co.uk/2/hi/science/nature/7533964.stm
Photo Glossary of Volcano Parts
http://www.pbs.org/wgbh/nova/volcano/anatomy.html#fea_top
http://glaciercaves.com/html/photog_1.HTM
Current Volcanic Activity
http://volcano.und.nodak.edu/vwdocs/current_volcs/current.html
Magma Types
Basaltic
http://www.theimage.com/geology/notes4/index10.html
Volcano Types
http://vulcan.wr.usgs.gov/Glossary/VolcanoTypes/framework.html
http://www.geology.sdsu.edu/how_volcanoes_work/Volcano_types.html
http://volcano.und.nodak.edu/vwdocs/vwlessons/volcano_types/index.html
Volcano Online Activity
http://www.cotf.edu/ete/modules/volcanoes/volcano.html
Volcano Quiz Game Online
http://www.scholastic.com/play/preVolcano.htm
Mount Pinatubo Eruption
http://geography.about.com/library/weekly/aa030901a.htm
Volcano Movies
“Dante’s Peak”
http://www.geol.umd.edu/pages/facilities/lmdr/dante/dante.htm
“Volcano”
Fun Volcano Stuff
BrainPop quick movie
http://magma.nationalgeographic.com/ngexplorer/0405/quickflicks/
Discovery Channel Site- VERY GOOD animations and volcano simulations. AWESOME!!!
http://dsc.discovery.com/convergence/pompeii/interactive/interactive.html
USGS Volcanoes Info
http://pubs.usgs.gov/gip/volc/cover2.html
Volcano World (Oregon State)
http://volcano.oregonstate.edu/
Volcanoes Info
http://www.geo.mtu.edu/volcanoes/
Earth’s Interior and Formation of Magmas
http://www.tulane.edu/~sanelson/eens211/earths_interior.htm
Divergent Volcanism Pic (TEST)
http://media-2.web.britannica.com/eb-media/53/4953-004-9D51CA25.jpg
Convergent Volcanism Pic
http://www.shropshirerocks.org/assets/userfiles/000075.jpg
E3.4A
World Map Distribution of Active Volcanoes and Plate Boundaries
http://www.scienceclarified.com/landforms/images/ueol_03_img0122.jpg
Good Pic of Plate Boundaries, Volcanoes, and Hot Spots
http://piru.alexandria.ucsb.edu/~geog3/lab_images/1-16.jpg
Measuring the size of volcanic eruptions (E3.4B)
VEI Info
http://www.geology.sdsu.edu/how_volcanoes_work/Variability.html
Article on the VEI
http://www.guardian.co.uk/education/2004/sep/02/research.highereducation