Volcanoes

volcanoes

• there are three stages to the life of a volcano
• EXTINCT- a volcano that is not likely to erupt in the near future if ever
• DORMANT- not erupting but could anytime
• ACTIVE- actively erupting 

Extinct Volcano

• no eruptions for over 10,000 years

Dormant Volcano

• Mauna Kea, Big Island
• Has not erupted in the last 10,000 years but still could

Milky Way Galaxy seen from Mauna Kea

Mount Hood

• an active volcano
• at least one eruption in last 10,000 years is an active volcano

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caldera

crater lake is a caldera

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cinder cone volcano

• made of tephra
• steep hill that is around or downhill from volcanic vent

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stratovolcano/composite

• conical volcano
• built of many layers
• hardened lava, volcanic ash, tephra, and pumics

crater

• circular depression in the ground
• caused by volcanic activity
• usually from the vent

crater vs caldera

• craters are typically the vent after eruption
• caldera is formed underground, like a crater with nearly vertical walls
• when the magma chamber underground empties, the pressure may be great

lava

• molten rock expelled from a volcano
• and the rock that cools and solidifies after an eruption

http://www.bigislandvideonews.com/2014/11/11/video-evening-lava-update-tues...

• lava has three chemical types
• lava has five morphologies

magma

• mix of molten or semi-molten rock, volatiles, and solids
• beneath the surface of Earth
• complex high fluid substance

magma chamber

• large underground pool of liquid rock mix
• found beneath the surface of the Earth
• under great pressure that over time will crack the rock around it

pyroclastic material

• pumice rich
• fountain lava
• lava thrown into the air with ash
• very hot 
• moves fast

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Mauna Loa

• shield volcano
• built almost entirely of fluid lava flowa
• large size
• low profile- like a warrior's shield

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vent

• opening on Earth's crust
• where lava and pyroclastic material erupts from Earth's crust

volcanic ash

• fragments of pulverized rock, minerals, and volcanic glass
• less than 2mm in size
• expelled from volcano

A'a & pahoehoe

• types of lava morphology
• a'a- forms large channels, high viscosity, slightly cooler
• pahoehoe- low volume flow, forms lava tubes, lower viscosity

volcanic dome

• sticky, thick magma that doesn't have enough pressure or gas
• it collects near the vent building up near the vent

lahar

• type of mudflow or debris flow 
• made of pyroclastic material, rocky debris, and water

hotspot

• places within the mantle where rock melts to generate magma
• Hawaiian Island chain 70 million years old
• not formed at plate boundaries

yellowstone hotspot

• 15 million years old

tephra

• fragments of rock and lava regardless of size
• it is blasted into the air through eruptions