Volcanic Hazards

Question 1

Vulcanicity

Answer 1

refers to all volcanic activities related to magma being forced out of the crust.

Question 2

Volcanoes

Answer 2

are openings in the Earth’s crust through which lava, ash and gases erupt.

Question 3

Formation of volcanoes

Answer 3

built by the accumulation of their own eruptive products: lava and tephra.

Question 4

Constructive plate margins volcanoes

Answer 4

Basaltic lava
Runny, less viscous
Little violence
Mainly Lava
Regular and can become continuous

Question 5

Destructive plate volcanoe

Answer 5

Acidic
Slow flowing, thick and viscous
Potentially explosive
Tephra pyroclastic flow and ash are the hazards

Question 6

Lava flow

Answer 6

Molten rock flowing over the surface.

Question 7

Pyroclastic flow

Answer 7

A mixture of hot rock, lava, ash and gases rising from a volcanic eruption that moves at a rapid speed (up to 200m/s) along the ground.

Question 8

Tephra

Answer 8

Solid rock fragments ejected during volcanic eruptions.

Question 9

Nuees Ardent

Answer 9

Means ‘glowing cloud’ and is a dense, rapidly moving cloud of hot gases, ashes and lava fragments from a volcanic eruption.

Question 10

Ash fallout

Answer 10

Ash can be ejected high into the atmosphere and, depending on prevailing winds, can cover a large area. Ash is highly abrasive and can cause breathing problems, disrupt machinery and clog filters. It can also obstruct sunlight, reducing visibility and temperatures.

Question 11

Mudflows / Lahars

Answer 11

Lahars are destructive mudflows formed when ash and other volcanic material are mixed with water. They flow at speeds of up to 60km/h and are highly erosive.

Question 12

Volcanoes occur

Answer 12

On linear belts along plate margins

Question 13

Magnitude of volcanoes

Answer 13

• The magnitude of a volcanic eruption generally refers to its explosive power. Since 1982 magnitude has been measured using a logarithmic scale known as the Volcanic Expolsivity Index (VEI)

Question 14

Ways to predict a volcanoe

Answer 14

SEISMOMETERS , tremors indicate that rising magma is fracturing and cracking overlying rocks.
Ground deformation is also measured using TILTOMETERS as the sides of volcanoes bulge slightly as the magma rises up.
gasses can also signal an imminent eruption. This can be picked up through REMOTE SENSING EQUIPMENT

Question 15

Prediction of volcanoes

Answer 15

often involves accurate hazard mapping (mapping the previous lava and pyroclastic flows by studying geology)

Question 16

Protection

Answer 16

involves reducing the risk of damage by preparing for an eruption.