volcanoes
DESCRIPTION
Volcanoes. Volcano Eruption. A volcano – is an opening in Earth’s crust through which molten rock, rock fragments, and hot gases erupt. . Magma. Also contains gases, which expand as the magma rises. Composed of silicon and oxygen compound. - PowerPoint PPT PresentationTRANSCRIPT
Volcanoes
Volcano Eruption•A volcano – is an opening in Earth’s crust through which molten rock, rock fragments, and hot gases erupt.
Magma•Composed of silicon and
oxygen compound•Also contains gases,
which expand as the magma rises
•Pressure builds up until the gases blacks out in a violent explosion
Magma
•Magma rises toward Earth’s surface if it is less dense than the surrounding rock.
•Magma chambers – holds magma until it can not hold any more and forces the magma out through an eruption.
Lava•Lava – is magma that has reached Earth’s
surface
Rock Fragments•Ash – tiny rock fragments.
Size of dust to rice grain. Can be carried long distances by wind (even all the way around Earth)
•Block – Can be the size of houses are solid pieces of rock. Fall quickly after eruption
• Cinders – bigger than ash, contain holes and tunnels left by escaping gases
Volcano Shapes and Sizes•Shapes of Volcanoes depend on Magma Feeding
1.) Most erupt from openings in bowl-shaped pits called craters.
2.) Some erupt from long cracks in the ground
Shield Volcano•Shaped like a broad,
flat dome.•Low silica (flows
easily)
Largest Volcano on Earth and one of the most active!
Name: Mauna LoaLocation: Hawaii Height: 10.5 miles most is
underwater!
Cinder Cone•A steep, cone-shaped
hill formed by the eruption of cinders and other rock fragments that pile up around a single crater. One of the most
famous volcanosName: ParícutinLocation: MexicoHeight: 1.73miles
Composite Volcano• A cone-shaped volcano built
up of layers of lava and layers of rock fragments.
• High silica (flows slower and is pasty)
Deadliest and most destructive volcanic event in the history of the US
Name: Mount St. Helens
Location: Washington, US
Height: 1.58 miles
Monitoring Volcanoes•Scientist monitor▫Magma movement▫Temperatures at openings, springs, and lakes on volcanoes
▫Amount and type of gases given off
▫Rising temperatures▫Changes in volcanic gases