volcanoes

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