What Are Volcanoes? 4/26/17

What are volcanoes? 4/26/17

• volcano=a weak spot in the crust,formed by plate tectonics,that erupts out magma/lava…Mt w/ hole in it filled with liquid rock
• magma=liquid rock INSIDE the volcano
• lava=liquid rock OUTSIDE the volcano
• Ancient Greeks thought volcanoes were the home of Hephaestus, God of Fire & Forge…Roman God Vulcan which gives the word “volcano”
• Ancient Polynesians/Hawaiians believed in Pele, goddess of the volcano
• Form on divergent & convergent PT boundaries
• Most explosive land form on Earth
• Volcanoes keep building up by erupting
• Can be extinct, never erupting again & be just a cone shaped mtn.
• Magma chamber is a “hot bubbling furnace”
• Created the atmosphere by releasing CO2
• Create while destroying
• Beautiful, yet deadly & dangerous…Nature’s fireworks show!
• Crater is created in the first eruption when the top is blown off the mtn.
• PT divergent & subduction zones create a weakness/crack in the crust where magma can escape
• Located on all continents except Australia
• Ring of Fire=lg volcanic belt outlining the Pacific Ocean; most volcanoes are here
• Island arc= arc of volcanoes formed along a deep ocean trench @ OvsO boundary: Japan
• Volcanic arc= arc of volcanoes formed along a CvsO boundary: Andes Mts in South America & Cascade Range of North America (Oregon & Washington)
• Hot spot volcanoes=volcano found in the middle of a plate rather than on a boundary: Hawaii & Yellowstone National Park (Wyoming/Montana)

What does a volcano look like on the inside? 5/3/17 (structure)

• ALL volcanoes have the SAME internal structure

1)crater= bowl shaped/indent area surrounding the vent @ the top of the volcano…where an eruption “starts”

2)pipe= long tube in the ground that connects the magma chamber to the surface/vent… “the straw”

3)vent= opening where magma comes out & turns into lava

4)magma chamber= pocket/pool of magma from the mantle @ the bottom of the volcano

5)side vent= vent on the side of the volcano

6)lava flow= flow of lava going down the volcanic mtn

Why do volcanoes erupt and what happens during an eruption? 5/9/17

• force of expanding gases pushes the magma from the chamber, through the pipe, out the vent
• gases are dissolved in magma
• gases expand b/c pressure from the earth decreases as magma rises
• Silica (SiO2) content of magma creates two types of eruption:

1)quiet eruptions= low silica magma; thin, runny, quiet oozing

*pahoehoe lava= HOT!! very runny & thin consistency/ low viscosity

*aa lava= hot! more viscous than pahoehoe

*lava flows, lava rivers, lava drips into the ocean, lava burps

*Hawaiian volcanoes

* “Blub-Blub”

2)explosive eruptions= high silica magma; thick, sticky, clogs vent like a cork!

* pyroclastic flow= mix of poisonous gases, ash, cinders & bombs hurtling down the volcano side HOTTTT!!!!!

* forms obsidian (volcanic glass) & pumice

*BOOMER!!!!

What are the different forms of volcanic mountain? 5/16/17

(glued in stuff)

• three stages of volcanic activity:

-active=is erupting right now

-dormant= “sleeping”-may erupt in the future

-extinct= will never erupt again…DEAD!

What other landforms are created by volcanic activity? 5/18/17

• caldera= a large crater formed by a large eruption when the magma chamber empties & collapses
• volcanic soil= broken down ash adds potassium & phosphorous to the soil making it ++++fertile
• dike=magma that hardened across layers of rock vertically or diagonally-II
• sill= magma that hardened between layers of rock horizontally-II
• volcanic neck=magma hardened in the pipe (Ship rock)-II
• batholith=LARGE dike/sill formation (Sierra Nevada Mtns)-II
• geysers=hot column of water and steam shooting in to the air (Old Faithful)
• hot spring=natural pools of earth heated water
• geothermal activity= “Earth heated”…hot springs & geysers & other stuff that happens in volcanic areas
• igneous intrusion (II)= when magma hardens underground “intruding” on the other rock layers

What did I learn from the video: Eyewitness Volcano 5/12/17