Volcanoes

Question 1

What are Lahars?

Answer 1

Mudflows of volcanic materials

Lahars can occur when volcanic ash and debris mix with water from heavy rain or melted ice caps.

Question 2

What can trigger a Lahar?

Answer 2

Heavy rain or melted ice caps

These triggers can lead to rapid flows down volcanic slopes.

Question 3

What was the impact of the 1985 Lahar in Colombia?

Answer 3

21,800 people died, 60,000 left homeless, 1.5 billion USD loss in property

This event was caused by melted ice caps mixing with volcanic ash.

Question 4

What are the characteristics of Lahars?

Answer 4

Vary between thick water and wet concrete, can remove structures

Lahars can destroy bridges, highways, and houses in their path.

Question 5

What leads to over-steepened slopes on volcanic mountains?

Answer 5

Addition of new material and magma intrusion

This can create gravitational instability, resulting in landslides.

Question 6

What are the consequences of blocked drainage systems due to volcanic activity?

Answer 6

Temporary dams that can fill with water and fail, causing floods

Pyroclastic flows and lava flows can block drainage systems.

Question 7

What can cause flooding after a volcanic eruption?

Answer 7

Gases emitted into the atmosphere and heavy downpours of rain

Volcanic ash or dust can lead to intense rainfall.

Question 8

What are Tsunamis in the context of volcanic eruptions?

Answer 8

Giant sea waves formed by volcanic activity

Tsunamis can occur when a volcano erupts and collapses into a body of water.

Question 9

What historical event is an example of a tsunami caused by a volcanic eruption?

Answer 9

1883 eruption of Krakatoa, Indonesia

This eruption generated 30-meter high waves and resulted in 3,600 drownings.

Question 10

What causes earthquakes associated with volcanoes?

Answer 10

Movement of magma within the Earth’s surface

These earthquakes can be felt before, during, and after an eruption.

Question 11

What can earthquakes triggered by volcanic activity lead to?

Answer 11

Landslides and tsunamis

Volcanic earthquakes can destroy infrastructure and cause fatalities.

Question 12

How can volcanism affect climate in the short term?

Answer 12

By injecting ash and gases into the atmosphere

This can lead to cooler temperatures due to reflection of solar radiation.

Question 13

What was the ‘year without summer’?

Answer 13

1816, following the eruption of Tambora volcano

This year experienced unusual snowfalls and cooler temperatures due to volcanic ash.

Question 14

What effect did the 1991 eruption of Pinatubo have on temperatures?

Answer 14

Lowered average temperature by about 1°C for two years

This was due to the ejection of large quantities of sulfur dioxide into the atmosphere.

Question 15

What role do volcanic gases like CO2 play in global warming?

Answer 15

They are greenhouse gases that help retain heat in the atmosphere

Volcanic eruptions can enhance global warming through these emissions.