volcanos science Flashcards
(40 cards)
What is a volcano?
A mountain formed by lava and or pyroclastics.
Define lava.
Magma that reaches the earth’s surface.
What are pyroclastics?
An igneous rock texture resulting from materials ejected from a volcano during a violent eruption.
What materials are included in pyroclastics?
- Rock fragments
- Ash
- Lava bombs
What gases are released during volcanic eruptions?
- Water vapor
- Carbon dioxide
- Sulfur dioxide
What are the three factors influencing volcanic eruptions?
- Magma composition
- The magma’s temperature
- The magma’s viscosity
Define viscosity.
A fluid’s resistance to flow.
What characterizes basaltic lava?
Usually very fluid and flows in thin broad sheets.
What is pahoehoe lava?
Rope-like flows with a relatively smooth skin, can still be flowing.
What is aa lava?
Lava that has a rough, jagged surface with dangerous sharp edges.
What are lava tunnels?
Conducts for flowing lava below a hardened surface.
What is pillow lava?
Lava that forms and cools in ocean water.
What causes pyroclastic materials to form?
Superheated gases expand explosively and blow pulverized rock and lava from a vent.
What is pumice?
Pyroclastic material that cools from frothy lava.
What are lapilli?
Walnut-sized pyroclastics.
What are bombs in volcanic terms?
Molten lava ejected from a volcano that hardens in the air.
What is a vent?
The pipe or opening from which lava flows from magma into lava.
Define conduit in a volcanic context.
The connection from the magma chamber to the vent.
What is a crater?
A steep-walled depression at the summit of a volcano.
What is a caldera?
An unusually large depression at the summit of a volcano.
What is a parasitic cone?
A secondary vent on the side of the volcano.
What are fumaroles?
Secondary volcanic vents where only gas comes out.
What is a shield volcano?
A slightly dome-shaped mountain formed by multiple eruptions of fluid lava.
