Volcanic Hazards + MAGMA content

Question 1

Lahar

Answer 1

Indonesian word describing a hot or cold mixture of water and rock fragments that flow down slopes/valleys of a volcano • Looks like mass of wet concrete with fragments

Question 2

Lahar Measurables

Answer 2

• Hundreds of meters wide and 10’s of meters deep • Travel very fast 10-100’s km/m

Question 3

Pyroclastic Flows

Answer 3

High density mixture of hot, dry rock fragments and hot gases • Erupted at high speeds • Destroy by direct impact • Bury sites with hot rock debris

Question 4

Pyroclastic Measurables

Answer 4

• Travel at up to 700km/hr • 600 degrees Celsius • ex Mount Pinatubo, Mt. St. Helens, Mt. Pele

Question 5

Volcanic ash/Tephra

Answer 5

• General term for fragments of rock blasted into the air o Mm-5m • Ex Iceland, Mt. St. Helens

Question 6

Lava Flows

Answer 6

a mass of flowing lava

Question 7

Magma Types

Answer 7

1. Basalt 2. Andesite 3. Dacite 4. Rhyolite (increasing order of silica content)

Question 8

What is the distinguishing factor between magma types?

Answer 8

Silica content (SiO2)

Question 9

Basalt Rock/Magma

Answer 9

Extremely high temperature (1100 degrees Celsius) least silica content amongst volcanic rocks Least violent eruptions Magma flows quickly and easily due to low viscosity/silica also very thin

Question 10

Andesite, Dacite, Rhyolite Rock/Magma

Answer 10

Flows very slowly due to high silica content low temperature (compared to Basalt) 900 Celsius thick and sticky and highly resistant to flow