Volcanoes
Notes:
Volcanoes Section 3
Inside the Volcano
•Beneath the surface magma collects in a pocket called the magma chamber
•The magma travels upward through a long tube called the pipe
•Molten rock and gas leave the pipe and travel up to the vent at the top of the volcano. There are vents also on the side of the volcano
•The crater is a bowl-shaped area at the top of the volcano
Volcano Eruptions
When a volcano erupts, the force of the expanding gases pushes magma from the magma chamber through the pipe until flows or explodes out of the vent.
When magma escapes from the volcano and becomes lava, the remaining gases bubble out.
Types of Eruptions: Eruptions depend upon the viscosity and the amount of silica content
•Quiet Eruptions – low in silica; low viscosity which will cause the lava to flow easy; letting gases bubble out gently; Hawaiian Island formed from quiet eruptions;
•Explosive Eruptions – high in silica; high viscosity making it thick and sticky; builds up pressure until it explodes
Lava fragments
* Volcanic ash – fine pieces ( speck of dust)
* Cinder - pebble-size particles
* Bombs – large pieces
* pyroclastic flow – hurls out a mixture of hot gases, ash, cinder, and bombs
Volcano Hazards:
Quiet Eruption
•Set fires
•Burying everything in its path
•Covers areas with thick lava
Explosive Eruption
•Deadly gases
•Ash, cinder, and bombs
•Volcanic ash in the atmosphere
•Landslides and avalanches
Volcanic Activity
Stages:
•Active – one that show signs of erupting
•Dormant – not active but is expected to awaken in the future
•Extinct – dead or unlikely to erupt again
•Geologist use instruments like tiltmeters and other instruments to detect slight surface changes. These changes will give warnings of a volcano erupt.