14.2 What are the main hazards generated by volcanic activity?

Question 1

What are the main hazards generated by volcanic activity?

Answer 1

The main hazards include lava flows, pyroclastic flows, tephra, toxic gas emissions, lahars, floods, and tsunamis.

Question 2

What type of lava is characterized by free-flowing behavior?

Answer 2

Basic (basaltic) lava is free-flowing and can run for considerable distances.

Question 3

What are pyroclastic flows?

Answer 3

Pyroclastic flows are a combination of very hot gases, ash, and rock traveling at high speed, following the contours of the ground.

Question 4

What does tephra refer to?

Answer 4

Tephra describes any material ejected from a volcano, ranging from fine ash to large volcanic bombs.

Question 5

What gases are emitted during volcanic eruptions?

Answer 5

Volcanic eruptions emit a range of toxic gases, including nitrogen, carbon dioxide, and sulphur dioxide.

Question 6

What are lahars?

Answer 6

Lahars are mud flows with the consistency of wet concrete, formed by melting snow and ice during an eruption.

Question 7

What is a Jokulhlaup?

Answer 7

A Jokulhlaup is a flood caused by volcanic eruptions beneath an ice field, resulting in rapid melting and accumulation of water.

Question 8

How can volcanic eruptions cause tsunamis?

Answer 8

The violent eruption of some island volcanoes can displace ocean water, creating tsunami waves capable of traveling at high speeds.

Question 9

What is the Volcanic Explosivity Index (VEI)?

Answer 9

The VEI is a scale that measures the explosivity of volcanic eruptions based on magnitude and intensity.

Question 10

What is a super-volcano?

Answer 10

A super-volcano is a volcano that erupts more than 1000 km³ of material in a single eruption event.

Question 11

What can be a long-term effect of volcanic eruptions?

Answer 11

Eruptions emitting large quantities of ash can lead to long-term climatic changes by blocking sunlight.

Question 12

What catastrophic event occurred in 1984 related to lahars?

Answer 12

Following the eruption of Nevado del Ruiz, the Colombian town of Armero was overwhelmed by lahars, resulting in 23,000 deaths.

Question 13

What is the impact of acid rain produced by volcanic gases?

Answer 13

Acid rain can damage crops and pollute surface water and soils.

Question 14

What is the significance of the 1883 eruption of Krakatoa?

Answer 14

The eruption created tsunamis that are believed to have drowned 36,000 people.

Question 15

What does VEI stand for?

Answer 15

Volcanic Explosivity Index (VEI) measures the explosiveness of volcanic eruptions.

Question 16

What is the range of the VEI scale?

Answer 16

The VEI scale ranges from 0 (gentle eruptions) to 8 (largest super eruptions).

Question 17

How does the size and frequency of eruptions change on the VEI scale?

Answer 17

Each increase in VEI indicates volcanoes that are 10 times bigger and occur less frequently.

Question 18

What is an example of a VEI 6 eruption?

Answer 18

Mount Pinatubo is an example of a VEI 6 eruption, which caused global temperatures to drop by half a degree for two years.

Also, Mount Tambora is noted for its significant impact.

Question 19

How often do VEI 8 eruptions occur?

Answer 19

VEI 8 eruptions occur approximately every 50,000 years.

Question 20

What significant event is associated with a VEI 8 eruption?

Answer 20

The extinction of the dinosaurs is associated with a VEI 8 eruption.

Question 21

How often do VEI 7 eruptions occur?

Answer 21

VEI 7 eruptions occur every 500 to 1,000 years.

Question 22

How often does Yellowstone erupt?

Answer 22

Yellowstone erupts approximately every 600,000 years.

Question 23

What is a caldera volcano?

Answer 23

A caldera volcano has a plug that stops magma from escaping.

Question 24

What are hotspots in volcanology?

Answer 24

Hotspots are areas where molten rock rises in a plume, but their formation is not fully understood.

Question 25

What happens as each pocket of melt stalls in a hotspot?

Answer 25

Heat is transferred to the surrounding mantle and asthenosphere.

Question 26

What is a dyke in relation to volcanism?

Answer 26

A dyke is formed when molten rock makes its way through cracks and fissures in the lithosphere.

Question 27

What occurs as a volcano grows above sea level?

Answer 27

The weight of the volcano bends the tectonic plate down.

Question 28

How does the distance from a hotspot affect volcanic eruptions?

Answer 28

The further away a volcano is from the hotspot, the less frequently it erupts.