volcanoes
DESCRIPTION
What are the different structures of volcanoes?TRANSCRIPT
Composite and shield volcanoes
By Odessa Ng
VOLCANOES
VOLCANOES • Volcano = opening in the ear th’s crust
• Eruption = magma, volcanic ash and gases escape from the surface.
• Different shapes and sizes
Stromboli Volcano
COMPOSITE VOLCANOES
• Also known as strato-volcanoes
• Cone shaped, steep sides
• Explosive eruption: lumpy lava
• Quiet between eruptions: seems extinct
STRUCTURE
Vicious magma (magma chamber)
1. Magma rises up to surface
2. Crater pipe clogged 3. Gas in crater pipe
gets locked up
4. Pressure increases, rocks, ash, lava thrown out several km(s)
FAMOUS EXAMPLES Name Location
Mount Etna • East Coast of Sicily, Italy • Tallest active volcanoe in Europe
Mount Pinatubo • On Island of Luzon • Provinces of Zambales, Tarlac
Mount St. Helens • Skamania County, Washington, US • Deadliest volcanic event in US history
ON THE MAP…
Mt Pinatubo
Mt Saint Helens
Mt Etna
SHIELD VOLCANOES • Built of fluid lava flows
• Occur at mid-ocean ridges and hot spots
• Flat shape, covers area of several km
• Quiet, yet constantly active
• Explosive upon contact with water
Mauna Kea in Islands of Hawaii
STRUCTURE
1. Very little pressure: Lava flows quietly out of the crater
2. Little pressure = No explosive eruption
3. Flow after flow of lava from the crater builds up the volcano
FAMOUS EXAMPLES Name Location
Mount Mauna Kea • Islands of Hawaii, USA
Mount Kilauea • Islands of Hawaii, USA
Espanola, Fernandina, Isabela
• Shield volcanoes in the Galapagos Islands, near S. America
ON THE MAP…
Mount Kilauea
Eruption of Fernandina
IMPACT ON PEOPLE AND ENVIRONMENT Houses may be burn down
Crops, farms totally destroyed
May result in many deaths if evacuation is not carried out quickly enough.
Threaten sensitive ecosystems
Toxic gases (carbon dioxide, sulphur oxide)harms the environment
Wildlife may be even wiped out.
Climate may be affected severely, depending on the eruption.
Diseases such as cholera may spread
Heavy ash fall makes breathing difficult.
Volcanic gases may be harmful to our bodies.
Impact