Chapter 3: Volcanoes and the Rock Cycle

Assignment 1:

Volcanic Eruptions

Question #1

• _____________________ are areas on Earth’s surface where magma and volcanic gases come out of the earth.

VolcanoesVolcanoes

Question #2

• _____________________ eruptions are the most common type of eruption. These involve the relatively calm flow of _____________.

• Add: Mostly occur above “hot spots” and in rifts (divergent boundaries).

Non-explosiveNon-explosive

lavalava

Non-explosive eruption

Question #3

• During an explosive eruption, clouds of hot _____________, ______________, and ___________ rapidly shoot out from a volcano.

debrisdebris

ashashgasgas

Explosive Eruption

http://upload.wikimedia.org/wikipedia/commons/4/45/MtRedoubtedit1.jpg

Question #4

• Explosive eruptions cause magma to be blown into small particles that __________ in the air. hardenharden

Question #5

• The body of molten rock deep underground that feeds a volcano is called a _____________ ________________. Circular openings through which this molten rock escapes are called the ________________ of the volcano.

Magma chamberMagma chamber

ventsvents

Question #6

• Magma that contains a high amount of ______________ and ________________is more likely to produce an explosive eruption. The _______________ tends to produce high gas pressures within the magma and the __________________ tends to make the magma stiff and slow flowing, which can produce “clogs” in the volcanic vents (this causes high pressures to build before an eruption occurs).

Water vaporWater vapor silicasilica

Water vaporWater vapor

silicasilica

Demonstrations

• “water bottle” volcanoes

• Virtual volcano

Question #7

Magma erupts from a volcano as either____________ or _________________.

lavalava

Pyroclastic material (tephra)Pyroclastic material (tephra)

Question #8

_______________________ forms when magma is blasted into the air and hardens or as existing rock is shattered during an explosive eruption.

Pyroclastic material (tephra)Pyroclastic material (tephra)

Question #9

A fluid that has difficulty flowing is said to have a high ________________.viscosityviscosity

Question #10

___________________ ________________ forms when cooling magma forms rock that is shattered into tiny slivers by the force of an explosive eruption. This can remain in the air for weeks or even years and travel far from the volcano.

Volcanic ashVolcanic ash

Question #11

The most dangerous hazard of an explosive eruption is a ______________________, in which enormous amounts of dust, ash, and gas is ejected from a volcano. Instead of rising, the heavy (and very hot) cloud sinks and races down the side of the volcano at speeds of over ____________ km/h (that’s about 120 miles per hour).

Pyroclastic flowPyroclastic flow

200200

A Pyroclastic Flow!

Another Pyroclastic Flow!

Yet another pyroclastic flow!?

You’ve got be to kidding, enough with the pyroclastic flows already!!!!

Pyroclastic flows

More pyroclastic flow video

Death on Mount Unzen

Pyroclastic flow videos

• Pyroclastic flow movie

• Educational

• Mt.Unzen deaths