Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
24 Cards in this Set
- Front
- Back
|
Viscosity
|
- The ability of lava to flow
- The more viscous a substance the slower it flows - Ex: Water has low viscosity, honey has high viscosity - The more silica the greater viscosity |
|
|
Highly Viscous Flow
|
- Dome-like shape
- Travels little distance - Much like toothpaste |
|
|
Viscous Flow
|
- Thick flows
- Travels some distance - Cone shape volcanoes |
|
|
Fluid Flow
|
- Thin flows
- Travels great distance - Shallow volcanoes |
|
|
Explosive Eruption
|
- Gray Eruption
- Violent eruption in which material is primarily ejected in the form of pyroclastic debris |
|
|
Effusive Eruption
|
- Red Eruption
- More benign eruption in which material is ejected primarily in the form of flowing lava flows |
|
|
Volcano Geomorphology
|
- Shape and structure of volcano
- Controlling factors = type of eruption and type of flow |
|
|
Typical Volcano
|
- Magma Chamber: accumulation of magma sitting beneath a volcano
- Crater - Summit Vent - Flank Vent |
|
|
Shield Volcanos
|
- Broad, gently sloped cones
- SIlica Content: low - Low Viscosity - Gas Content low - Type of flow: thin - Type of eruption: primarily effusive lava flows |
|
|
CInder Cones
|
- Steep, sloped piles of volcanic debris and some lava flows
- Silica content intermediate - Viscosity: intermediate - Gas Content: intermediate - Type of flow: thin - Type of eruption: very explosive at vent; effusive lava flows |
|
|
Stratovolcano (Composite)
|
- Very large cone-shaped mountain
- Silica Content: high - Viscosity: high - Gas content: high - Type of flow: thick, dome - Type of eruption: primarily explosive pyroclastic eruptions - Alternating eruption of explosive pyroclastic material and effusive lava flows builds a “stratifies” volcanic cone - The steep-sides stratovolcanoes are prone to landsliding |
|
|
Stratovolcanoes: Biggest Hazards
|
- Ashfall
- Pyroclastic Flows - Lahar - Landslide |
|
|
Ashfall
|
- Ash chokes machinery, block airways, covers vegetation and fields, causes structural collapse
- Volcanic ash: consists of microscopic particle of rock shards and glass |
|
|
Pyroclastic Flows
|
Fast moving avalanche of hot gas, ash and pyroclastic debris also known as a “nuee ardente” or “glowing cloud”
|
|
|
Lahar
|
Fast-moving mudflow-like slurry of ash, debris and water
|
|
|
Landslide
|
Unstoppable slopes fail and disrupt roads, cover fields, destroy homes and dam creeks and rivers
|
|
|
Hawaiian Islands
|
- The Hawaiian Islands are 3250km from the nearest plate boundary
- The Hawaiian Islands are the Eastern-most part of a volcanic mountain chain that is largely underwater - 8 Major Islands - Active Volcanoes: Mauna Loa, Loihi and Kilauea (currently producing lava flows) |
|
|
Major Hot-Spots
|
A location at the base of the lithosphere at the top of a mantle plume where temperatures can cause melting
|
|
|
Hot-Spot Track/Chain
|
A chain of now-dead volcanoes transported off the hot-spot by the movement of a tectonic plate
|
|
|
Hot-Spot Volcano
|
An isolated volcano not cause by movement at a plate boundary, but rather by the melting of a mantle plume
|
|
|
Pillow Basalt
|
blob-like shaped pieces of lava formed under water
|
|
|
Lava Bombs
|
lava blown into the air that “freezes”
|
|
|
Pahoehoe Flows
|
ropy surface texture (cools faster on the outside)
|
|
|
Aa Flows
|
rubbly flow with jumbled angular pieces (lava cooled on outside but inside lava flows and tears apart outside lava)
|
