Eruptions and Forms of Volcanoes

1
Eruptions and Forms of Volcanoes
2
10.1 Volcanoes and Earths Moving Plates

• Most active volcano Kilauea
• Located in Hawaii
• Magma formed Heat and pressure cause rock to
  melt

3

• What causes magma up? It is less dense than
  surrounding rock.
• Divergent boundaries
• plates move apart
• Ex Mid Atlantic Ridge
• Convergent boundaries
• plates move together
• Ex Himalayas

4

• Pacific Ring of Fire- the area around the Pacific
  Plate where earthquakes and volcanoes are common

5

• Hot spot- areas in the mantle that are hotter
  than their surroundings
• Ex Hawaiian Islands, Yellowstone National Park

6
10.2 Energy from Earth

• How does geothermal energy produce electricity?
• Heat and energy from magma is used to boil water
  to produce steam used to generate electricity.
• Used in
• California, Nevada,
• Utah, Hawaii

7
3 benefits of using geothermal energy

1. Reduction in oil spills on coastlines
2. No mine waste or radioactive waste
3. Reduction in pollutants from burning fossil fuels

8
2 types of geothermal energy

• Magma- molten rock deep inside Earth
• Hot dry rock (HDR)- water is pumped into the
  cracks in rock- heated then used to create steam
• Which type is more available? Hot dry rock
• Why? Temperatures increase with depth into Earth

9

• Which type of geothermal energy produces fewer
  carbon dioxide emissions? Hot dry rock
• Why is HDR not used more?
• It is too expensive

10
2 important factors that determine whether a
volcano will be explosive or quiet.1.) the
amount of gases trapped in magma.2.) the
composition of the magma.
11
Basaltic magmas generally produce quiet
eruptions.Why?Basaltic magma contains less
silica and is less viscous (sticky).
12
Example Hawaiian Islands
13

• Granitic magmas generally produce explosive
  eruptions.
• Why?Granitic magma contains more silica and is
  more viscous (stickier).

14
Example Mount Saint Helens
15
Another factor that causes granitic magma to be
explosive is the high water vapor content.
16
Andesitic magma has medium silica content (medium
viscosity)Andesitic volcanoes are explosive.
17
A. Composite (stratovolcano)
18
B. Cinder Cone
19
C. Shield Volcano
20
laccolith
sill
dike
magma
batholith
21
Batholith largest intrusive rock bodies.
(greater than 100 km)How? Form when a large
plume of magma cools underground.
22
dike magma squeezes into a vertical
crack.sill magma squeezes between horizontal
rock layers.
23
Volcanic neck weathering erosion remove the
sides of a volcano leaving the solidified vent.
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
5. Caldera when the top of a volcano collapses
after a large eruption.