Volcanoes

Question 1

Name some key words for volcanoes

Answer 1

Lava, vent, fissure, cone, plateau, silica, active, dormant, extinct, hotspot, pyroclasts, pyroclastic flow, volcanologist, volcano, ridge VEI scale, Pacific Ring of Fire

Question 2

Where do volcanoes happen?

Answer 2

• Constructive plate boundary
• Destructive plate boundary
• Hotspots

Question 3

What is a volcano?

Answer 3

A volcano is a mountain formed by the eruption of magma on the Earths surface through a hole or vent in the Earths crust. Once the magma comes through the volcano and reaches the surface, it is called lava. Lava cools quickly to form basalt rock.

Question 4

What is the life cycle of a volcano?

Answer 4

• Active - Has erupted in the past 100 years e.g. Mt. St. Helens (USA)
• Dormant - Has not erupted in the past 100 years but may erupt again e.g. Mt. Fuji (Japan)
• Extinct - A volcano which has not erupted in historical times e.g. Mt. Slemish (co. Antrim)

Question 5

Name 3 positive effect of volcanoes

Answer 5

1. Creates fertile land - Good for farming/growing crops - Slope os Mt. Vesuvius - Fruit Farms
2. Tourism - Pompeii has been preserved & draws thousands of tourists each year - Pompeii (destroyed in 79 AD)
3. Geothermal energy - 90% of homes heated & industry runs on geothermal energy - In Iceland

Question 6

Name 3 negative effects of volcanoes

Answer 6

1. Loss of life - Pompeii city was destroyed by Mt. Vesuvius eruption, killing 20,000 people - Pompeii (79 AD)
2. Disruption to flights - Icelandic volcano erupted and the ash grounded flights throughout Europe in the summer of 2010 - Icelandic Volcano
3. Lahar - Fast moving mudflow when ash & melt water mix - Loss of life & destruction to buildings - Nevando Del Ruiz (in Colombia) (1785)

Question 7

Name 3 types of impacts

Answer 7

• Economic impacts
• Environmental impacts
• Social impacts

Question 8

Mt. St. Helens Eruption: Background

Answer 8

1. It was a lateral (sideways) eruption
2. It happened in 1980
3. It was in Washington (USA)

Question 9

Mt. St. Helens Eruption: Impacts

Answer 9

Social Impacts - Loss of life & destruction of buildings
Environmental Impacts - Forests were obliterated & floods
Economic Impacts - Cost of $1 billion in America & businesses had to shut down

Question 10

Monitoring volcanoes

Answer 10

It is the job of a volcanologist to monitor, study & predict volcanic activity. Before a volcano erupts, it often sends early warning signs such as:
- Small earthquakes
- Increased gas emissions
- Eruptions of steam of rocks

Question 11

Measuring volcanic Eruptions

Answer 11

To measure to the force of eruptions, we use the Volcanic Explosivity Index (VEI) scale. The VEI scale uses the amount of ash & the height of the ash cloud that erupted from the volcano to rank volcanic eruptions. The scale ranges from the weakest eruption at 0 to the strongest at 8 VEI.