Volcanoes

Comes from the island of Vulcano off Sicily People believed that Vulcano was the chimney of the forge of Vulcan, the blacksmith to the Roman gods.

Sometimes magma can leak from divergent or convergent plate boundaries. As it rises, gases within the magma expand, causing the magma to expel from the volcano.

Oceanic/Continental Volcano

Volcanoes are built by – Lava bombs—crusted over lava blobs – Ashflows—landslides of volcanic ash and gases – Tephra—airborne ash and dust – Flowing magma

Types of Volcanoes Shield Volcano—low viscosity lava such that gases can escape; associated with oceanic plates (low silica), lava can flow far

Lava Dome High viscosity lava, can form within other craters, violent explosions

Cinder Cone Small pieces of scoria/pyroclastics (cinders) that build up around the vent

Stratovolcanoes (Composite) Made of different layers of ash, lava, and cinders. Like chocolate shell on ice cream. Very explosive.

Popocatepetl

Supervolcano Large caldera Able to disrupt the global climate with ash and sulfur

Submarine volcanoes Common on the ocean floor (mid ocean ridge) Discolor water with gases and make pumice rafts and pillow lava

Two basic types of lava A’a Forms from viscous lava

Pahoehoe lava Smooth, ropey texture, less viscous

What does it mean to be extinct? Unlikely to erupt again, ever. What does it mean to be dormant? Not erupted in the last 10,000 years, but still possible eruption.

What effects does a volcano have? Besides the obvious dangers of lahars, pyroclastic flows, steam, poison gases, lava, and explosions, a volcano can do the following: – Injects huge amounts of CO2, SO2, HCl, HF, and ash into the stratosphere. Raises albedo of Earth. Cooling can cause famine Destroys ozone Causes acid rain Volcanoes release teragrams of CO2 each year

Moon shows volcanic history (maria, domes) Venus possibly has active volcanoes and has evidence of major volcanic activity Olympus Mons on Mars

Io, Jupiter’s moon is the most active object in the solar system because of tidal forces.

Cryovolcanoes Exist on Triton (Neptune), Europa (Jupiter), Enceladus (Saturn) – Ice volcanoes, water ejects and freezes on surface

Haleakala (House of the Sun)

Fuji

Mt. Vesuvius