Tsunamis and Volcanoes

Question 1

How would you describe a tsunami?

Answer 1

Wave or series of waves caused by the displacement of a large volume of water

Question 2

What causes a tsunami?

Answer 2

Seismic activity, landslides, volcanic eruptions

Question 3

What happens when a tsunami wave reaches land?

Answer 3

water depth decreases, wave speed decreases, wave height increases

Question 4

What are the impacts of a tsunami?

Answer 4

Destruction of land and infrastructure, injury and death, contaminated drinking water, disease, economic impacts

Question 5

Tsunami warning system?

Answer 5

Did not exist in the Indian Ocean in 2004; DART (Deep-ocean Assesment and Reporting Tsunamis)

Question 6

How do we reduce tsunami impacts?

Answer 6

Warnings/bulletins if tsunami detected, warning signs, bioshields (vegetation acts as barrier between tsunami and infrastructure)

Question 7

What is DART?

Answer 7

Deep-ocean Assessment and Reporting Tsunamis; Pressure sensor detect tsunami passing above

Question 8

What is a volcano?

Answer 8

Opening in the earth’s crust through which lava, volcanic ashes, and gases escape

Question 9

What is lava?

Answer 9

molten rock that breaks through earth’s surface

Question 10

What is magma?

Answer 10

molten rock underground that contains dissolved gases

Question 11

What is being erupted at mid-ocean ridges?

Answer 11

basalt

Question 12

What is being erupted above hot spots?

Answer 12

basalt

Question 13

What is being erupted at subduction zones?

Answer 13

andesite

Question 14

What is being erupted as magma moves up through crust?

Answer 14

rhyolite

Question 15

Each rock type has different silica content: What does high silica content entail?

Answer 15

High viscosity

Question 16

What type of lava flows are there?

Answer 16

a’a, blocky, and pahoehoe

Question 17

What is the texture and viscosity of a’a flow?

Answer 17

rubble-like texture, broken blocks, high viscosity

Question 18

What is the texture and viscosity of pahoehoe flow?

Answer 18

smooth ropy texture, low viscosity

Question 19

What is the texture, viscosity, and rock of blocky flow?

Answer 19

Large angular blocks, steep flow fronts, usually andesitic or basaltic andesitic, higher viscosity

Question 20

What characterizes basalt magma?

Answer 20

fine-grained, mafic igenous rock characterized by lower viscosity and lower gas content

Question 21

What characterizes andesite and rhyolite magma?

Answer 21

Increasing silica content, usually melting subducting plate, blocky lava flows

Question 22

How does basaltic, andesitic, and felsic lava flow?

Answer 22

B: Low viscosity and can flow long distances

A: Too viscous to flow far and tends to break up as it flows

F: So viscous may pile up in a dome-shaped mass

Question 23

Volcano type is partially dependant on magma viscosity - reflected in rock type: what are the four volcano types?

Answer 23

Shield volcano, composite or stratovolcano, volcanic dome, cinder cone

Question 24

What are the four rock types associated with each volcano?

Answer 24

Shield volcano: Basalt
Composite or stratovolcano: Andesite
Volcanic dome: Felsic
Cinder cone: Basalt

Question 25

Magma and gas content are connected. Why?

Answer 25

Greater gas content=more explosive

Question 26

Which type of magma has more gas than basaltic magma?

Answer 26

Rhyolitic magma

Question 27

Why does high viscosity result in a bigger explosion?

Answer 27

The high viscosity makes it difficult for gas to escape, so pressure builds

Question 28

How is a caldera created and what is its size?

Answer 28

Collapse of a volcano’s magma chamber, gigantic, more than 100km diameter

Question 29

How is a crater created and what is its size?

Answer 29

Outward explosion, up to a few km in diameter

Question 30

Where is a crater located?

Answer 30

Basin above a volcano’s vent

Question 31

Physical characteristics of a shield volcano?

Answer 31

Largest on earth: broad, gently sloping cone, flat, dome shape

Question 32

Physical characteristics of stratovolcanoes (composite)?

Answer 32

Slopes, the beautiful kind of volcano, but can be lethal.

Question 33

Which volcano is associated with subduction zones?

Answer 33

Stratovolcanoes (composite)

Question 34

Physical characteristics of cinder cones?

Answer 34

Bowl-shaped crate at the summit, rarely rise more than a thousand feet above their surroundings

Question 35

Two types of eruptive styles?

Answer 35

Effusive: produces lava flows, “peaceful”

Explosive eruptions: produces pyroclastic flows, erupts or blows up