VOLCANOES

CAUSES OF VOLCANOES

• Volcanic eruptions can happen at destructive and constructive boundaries, but not at conservative boundaries.
• Magma rises through cracks in between plates & weakenesses in the Earth's crust
• When pressure buildup is released, magma explodes to the surface
• The lava from the eruption cools to form new crust.
• Over time, after several eruptions, the rock builds up and a volcano forms.

MAGMA VS LAVA

• Magma is molten rock when it is still underground
• Lava is molten rock after it has erupted

ACTIVE VS. EXTINCT

• An active volcano has had at least one eruption during the past 10,000 years
• An active volcano might be erupting or dormant.
• An extinct volcano has not had an eruption for at least 10,000 years
• Extinct volcanoes not expected to erupt again in a comparable time scale of the future

MOUNT ETNA

• Active Stratovolcano in Sicily, Italy
• Last eruption June 2014
• Elevation is 10,991 ft
• Etna is the largest volcano in Europe

GLACIER PEAK

• Stratovolcano in Oregon
• Last eruption about 1700
• Elevation is 10,541ft
• High threat potential

3 NEGATIVE EFFECTS

• Lava flows and lahars can destroy settlements and landscapes
• Many lives can be lost as a result of a volcanic eruption.
• Volcanic ash clouds the air and blocks out the sun