(TEST 1) Earth Science, Lecture pt 3 (ch 6 and 7) Flashcards
What 4 settings does volcanic activity usually occur in?
- Isolated hot spots/ mantle plumes
- Volcanic arcs bordering deep ocean trenches (convergent)
- Mid-ocean ridges (divergent)
- Continental rifts (divergent)
What is viscosity?
The resistance to flow of a fluid
What does viscosity depend on?
Silica content, temperature, and volatiles
How does high temperatures affect viscosity?
They make viscosity lower
How does low temperatures affect viscosity?
They make viscosity higher
How does lower volatiles affect viscosity?
They make viscosity lower
How does higher volatiles affect viscosity?
They make viscosity higher
What are the types of volcanoes?
Shield volcanoes, stratovolcanoes (composite volcanoes), lava domes, cinder cones (scoria cones), caldera.
What are some primary effects in volcano hazards?
- Lava flows
- Pyroclastic Activity
- Release of gases
What are some secondary effects in volcano hazards?
- Debris flows
- Mud flow/ lahars
- Debris Avalanches
- Floods
- Fires
What is pyroclastic activity?
A mixture of rock, ash, and gas that travels quickly.
Which one is more dangerous, pyroclastic activity or lava flow?
Pyroclastic activity because they spread around faster and farther, and because they are ejected more suddenly.
What is a caldera?
A gigantic volcanic depression
What are stratovolcanoes?
Large, cone-shaped volcanoes with steeper slopes
Magma may erupt along a linear tear called
Fissure
What is Lahars?
Mudflows that result when water moves ash
What are some warning signs that can indicate that an eruption is imminent?
Tremors
Heat flow
Changes in shape
Emission increases
What are hotspots?
A large plume of hot mantle material rising from the Earth
What is mass movement?
When the force of gravity causes rocks and soils to move downslope
What is a landslide?
Sudden event in which large quantities of rock and soil plunge down steep slopes.
What are the different types of motion?
Fall, slide, and flow
What does water saturation reduce?
Friction
What are the two types of slides?
Rotational slides and translational slides
Where does earthflow usually occur?
Occurs on hillsides in humid areas during times of heavy
precipitation or snowmelt
What is creep?
Gradual downhill movement of soil and regolith. Very slow process
What is solifluction?
Slow, downslope flow of water-saturated materials common
to permafrost areas
What are submarine slumps?
Semi coherent blocks break and slip along failure planes.
What are submarine debris flow?
Broken material moves as a
slurry of mud with larger clasts.
What two positive effects does revegetation have?
It removes water by evapotranspiration and the roots help to bind and anchor regolith.
What is regrading?
Redistributing a slope by terracing removes some of the mass loading and catches debris.
What is a slump?
Downward sliding of a mass of rock or unconsolidated
material moving as a unit along a curved surface
What is undercutting?
A variety of remedial steps can stabilize unstable ground.
What is debris flow composed of?
It is composed of volcanic
materials on the flanks of
volcanoes
