How do volcanoes form and what affect do they have on the Earth?

Along convergent boundaries:Above subduction zonesMagma forced upwards and forms

volcanoes on surfaceRing of Fire in Pacific OceanMediterranean belt – Mt. Vesuvius

Along divergent boundaries:At mid-ocean ridgesMagma fills in gaps Iceland – Mid-Atlantic Ridge

Hot Spots are unusually hot regions of Earth’s mantle where plumes of magma rise to surface

Located away from plate boundaries

Example: Hawaii

Active Erupts RegularlyLifetime can span

months to millions of years

Can be currently erupting or showing signs of unrest (earthquakes, emitting gas)

Ex: Mt. St. Helens

ExtinctUnlikely to erupt againNo magma/lava supplyEx: Hawaiian Islands

not over hot spot

DormantErupted in past but is

now quietCan be very dangerous

It is very difficult to determine status of volcanoes

Volcanoes emit water vapor, carbon dioxide, and sulfur dioxide into the air

Gases are suspended in atmosphere and block radiation from sun

Global temperatures can be affected Health issues for humans (Respiratory) Pyroclastic flows, tephra, lahars (hot

mud flow)

Volcanologists study deposits left from previous eruptions

Warning Signs: earthquakes activity and gas emissions

Seismometers measure EQs and correlation spectrometers measure SO2 levels

Structural support – walls, supportive buildings

Evacuation procedures

Communication between scientists and public

Volcanoes may have been present in the history of other planetsMars, Venus

Volcanoes are active on Jupiter's moon, Io