EOSC 114 Volcanoes Exam Questions with
Correct Answers
What does chemical and physical properties of the melted source rock determine?
- magma explosivity, type of explosive eruptions, products erupted from volcanoes
Magma
-what it is comprised of and how it is made
- denser than solid rock?
- formed by melting pre-existing rock in Earth's interior
- comprised of melt, crystals/minerals, gas bubbles
- less dense than solid rock so rises to surface of earth
- some magma gets trapped in crust, some can travel thru cracks in crust and flow onto
Earth's surface
What are the requirements for Magma to rise through the crust?
- what do these depend on
1. less dense than crust
2. runny (low viscosity
3. how enough to stay liquid
- depend on magma's composition and temperature
Lava
magma that has reached the earth's surface and cools to form solid rock
What is made when Magma rises to earth's surface?
,- contributes to formation of:
- oxygen, silicon, aluminum (earth's crust)
- iron
- calcium
- magnesium, sodium, patassium, etc
What elements are found in magma
8 elements, O and Si are in the greatest amount
What do minerals in magma crystalize into most of the time?
silicate minerals due to abundance of Si and O in earth's crust and upper mantle
(siO4) -4
What are the types of crystals that form in solidified magma
- sizes depend on how long it takes magma to cool
1. intrusive rocks - formed from magma that cools slowly underground in crustal magma
chambers
- large, about to see with naked eye
- thousands of years
- interlocking texture of grains
3. extrusive rocks
- quickly cooling magma
- days-weeks
- found in lava (magma on surface)
, - tiny crystals (cant see)
- fine-grained texture
List the types of volcanic products
1. lava flows
2. volcanic gases
3. pyroclastic material
4. gaseous products
Lava Flows
- result when magma with LOW gas content erupts EFFUSIVELY (not explosively) at earth's
surface
- surface lava flow can be:
- pahoehoe- ropy textured
- 'a'a - rubble-y flow top consisting of broken fragments of lava
panhoe hoe and 'a'a
are volcanic products called lava flows that occur on the surface of the earth
volcanic glass
- when magma erupts and cools very quickly that crystalization does not occur, it instead
solidifies into glass (supercooled liquid)
- glass is not crystalline
- if large - obsidian
- if lots of bubbles - pumice --> low density, floats on top of water
obsidian
Correct Answers
What does chemical and physical properties of the melted source rock determine?
- magma explosivity, type of explosive eruptions, products erupted from volcanoes
Magma
-what it is comprised of and how it is made
- denser than solid rock?
- formed by melting pre-existing rock in Earth's interior
- comprised of melt, crystals/minerals, gas bubbles
- less dense than solid rock so rises to surface of earth
- some magma gets trapped in crust, some can travel thru cracks in crust and flow onto
Earth's surface
What are the requirements for Magma to rise through the crust?
- what do these depend on
1. less dense than crust
2. runny (low viscosity
3. how enough to stay liquid
- depend on magma's composition and temperature
Lava
magma that has reached the earth's surface and cools to form solid rock
What is made when Magma rises to earth's surface?
,- contributes to formation of:
- oxygen, silicon, aluminum (earth's crust)
- iron
- calcium
- magnesium, sodium, patassium, etc
What elements are found in magma
8 elements, O and Si are in the greatest amount
What do minerals in magma crystalize into most of the time?
silicate minerals due to abundance of Si and O in earth's crust and upper mantle
(siO4) -4
What are the types of crystals that form in solidified magma
- sizes depend on how long it takes magma to cool
1. intrusive rocks - formed from magma that cools slowly underground in crustal magma
chambers
- large, about to see with naked eye
- thousands of years
- interlocking texture of grains
3. extrusive rocks
- quickly cooling magma
- days-weeks
- found in lava (magma on surface)
, - tiny crystals (cant see)
- fine-grained texture
List the types of volcanic products
1. lava flows
2. volcanic gases
3. pyroclastic material
4. gaseous products
Lava Flows
- result when magma with LOW gas content erupts EFFUSIVELY (not explosively) at earth's
surface
- surface lava flow can be:
- pahoehoe- ropy textured
- 'a'a - rubble-y flow top consisting of broken fragments of lava
panhoe hoe and 'a'a
are volcanic products called lava flows that occur on the surface of the earth
volcanic glass
- when magma erupts and cools very quickly that crystalization does not occur, it instead
solidifies into glass (supercooled liquid)
- glass is not crystalline
- if large - obsidian
- if lots of bubbles - pumice --> low density, floats on top of water
obsidian
