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