VolcanoesVolcanoes

The Earth’s land builders.The Earth’s land builders.

What is a volcano?What is a volcano?

• The land around an opening in Earth’s crust where molten rock exits the earth.

Is all lava the same?Is all lava the same?

• Pahoehoe• Aa• Pillow Lava

Do all volcanoes erupt violently?Do all volcanoes erupt violently?

• No. All volcanoes are different. Some erupt violently due to trapped gasses. Some flow gently due to a low viscosity.

What kinds of volcanoes are there?What kinds of volcanoes are there?

• Composite

• Shield

• Cinder Cone

• Caldera

• Lava Plateau

Composite Mt ShastaComposite Mt Shasta

Shield Mauna LoaShield Mauna Loa

Cinder Cone Wizard IslandCinder Cone Wizard Island

Caldera Crater LakeCaldera Crater Lake

Lava Plateau Columbia PlateauLava Plateau Columbia Plateau

Where are volcanoes found?Where are volcanoes found?

• Plate Boundaries

• Hot Spots

What is the biggest volcano?What is the biggest volcano?

• Depends on what biggest means.– Diameter– Height above sea level– Height above base– Highest volcano- Ojos del Salado – World’s largest- Mauna Loa– Solar System- Olympus Mons

• http://www.skimountaineer.com/ROF/VolcanicSeven.html

What comes out of volcanoes?What comes out of volcanoes?

• Lava• Pyroclastic material

– Ash– Lapilli– Blocks – Bombs

• Gas– Water vapor– Sulfur dioxide– Carbon dioxide and carbon monoxide– Hydrogen– Hydrogen sulfide and others

GasesGases

• Gases can be released even when a volcano is not erupting

• Vents that expel gas from a volcano are called fumaroles.

How do volcanoes affect the Earth?How do volcanoes affect the Earth?

• Land formation and mountain building

• Expelled water adds to our hydrosphere

• Expelled gases change our atmosphere

• Expelled gases and particulates can change our weather

• Eruptions can destroy towns/cities

• Toxic gases can smother living things

Do volcanoes affect our Do volcanoes affect our weather/climate?weather/climate?

• Yes. Volcanic ash is reflective and can cool the earth locally. This effect may last days to months.

• Volcanic gases such as sulfur dioxide SO2 convert to sulfuric acid H2SO4 in the atmosphere

• Sulfuric acid aerosols (tiny droplets) remain in the atmosphere for months to years.

Can we predict eruptions?Can we predict eruptions?

• Somewhat. Scientists monitor volcanoes

• Seismic activity

• Sulfur dioxide gas

• Ground deformation such as swelling or bulges

• Evacuation plans are in place in high risk areas

What other planets/moons have What other planets/moons have volcanoes?volcanoes?

• Mars- Old inactive volcanoes– Olympus Mons over 16 miles high

• Our Moon- Old inactive volcanoes

• Venus- Some may still be active

• Io- Moon of Jupiter• http://geology.com/articles/active-volcanoes-solar-system.shtml