-
What are the three types of volcanoes?
- Shield volcanoes
- Tephra cones
- Stratovolcanoes
-
What does a Shield volcano look like?
- Broad
- Dome shaped
- Gentle slopes
- HUGE
-
What composition does a Shield volcano have?
Basaltic
-
What kind of flow does a shield volcano have?
Lava
-
What does a Stratovolcano look like?
-
What kind of flow does a Stratavolcano have?
Pyroclastic and Lava
-
What composition does a Stratovolcano have?
Andesitic
-
What does a Tephra cone look like?
- Small
- formed from pyroclastic debris around a vent
- magma is gas rich
-
What composition does a Tephra cone have?
Basaltic
-
What flow does a Tephra cone have?
Pyroclastic
-
What are craters?
Depressions near summit from which volcanic materials are ejected
-
What are Lava Domes?
Late-stage, very viscous lava extruded after most gas exsolved
-
What are calderas?
- Circular, steep walled basins >1km in diameter near summit
- HUGE
-
What is a Resurgent dome?
- Due to uplift of caldera
- also small tephra cones/lava flows
-
What are Diatremes?
Volcanic pipes filled with rubble of broken rock
-
Is all lava erupted from volcanoes?
No
-
What are Fissure Eruptions?
- Extrusion of basaltic lava along elongate fractures
-
What are Plateau basalts?
Wide, flat plains produced by lavas from fissure eruptions
-
What are Pillow basalts?
Pillow shaped masses of basalt formed by submarine eruptions
-
What are Ash Flows?
- Andesitic or Rhyolitic magma
- Less common than basalt
- DESTRUCTIVE
-
What causes Thermal Springs?
Ground water heated by hot rock in or near old magma bodies
-
What is a Geyser?
- Thermal spring that displays intermittent eruptions of water and steam
- Pressure builds and water reaches above boiling point
-
What are 5 Volcanic Hazards?
- Pyroclastic flows
- Burial and or suffocation from ash
- Mudflows
- Tsunami
- Famine
-
What is Magma?
Molten Rock, together with any suspended mineral grains and dissolved gases, that forms by melting of rock in crust and mantle
-
What is a Volcano?
Vent from which magma and gases are erupted
-
What is Lava?
Magma that reaches earth's surface
-
What is Magma made out of?
- Si02 always predominant
- Characterized by high Temperatures
-
How hot is Magma?
1000 - 1200 degrees Celsius
-
What is Viscosity?
The thickness of lava
-
Higher temperature lava will have a ________ viscosity.
-
Low temperature lava will have a _______ viscosity.
-
Lava that is High in Si02 will have a ______ viscosity.
-
Lava that is Lower in Si02 will have a ______ viscosity.
-
What is Pahoehoe?
Smooth ropy-surfaced lava formed from very hot fluid lava
-
What is Aa?
Rubbly, rough-looking lava formed from cooler, very viscous lava
-
What does lower density cause in magma?
Slowly rise
-
What are some examples of Nonexplosive volcanoes?
- Lava fountain
- Spatter cone
- Lava Tube
- Vesicles
-
How does a Lava fountain form?
Forms when basaltic magma rises so rapidly that gas bubbles from solution
-
How does a spatter cone form?
Forms when bits of falling lava pile up beside the vent
-
What are Lava tubes?
Subsurface channels in Pahoehoe lava flows
-
What is a Vesicle?
- Gas bubble holes preserved in solidified rock
- produces rocks with vesicular texture
-
What are Amygdules?
Vesicles filled by secondary minerals
-
What type of Magma is explosive?
Viscous Andesitic and Rhyolitic with high dissolved gas content
-
What is Pumice?
Froth of innumerable glass walled bubbles
-
What is ash?
Tiny fragments of shattered solidified magma
-
What is a Eruption Column?
Mixture of hot gas and tephra rising rapidly into the air
-
What is Tephra fall?
Rain of debris particles as eruption cloud drifts with upper winds
-
What is a Pyroclastic flow?
- Denser than air
- mixture of hot gas and ash
- fast and lethal
-
What is Ignimbrite?
Solidified deposit resulting from pyroclastic flow
-
What is a Lateral Blast?
Sideways eruption
|
|
