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Volcanoes Chapter 6. What are volcanoes?. They are openings in the Earth that erupt gases, ash, and lava. Kilauea – most active volcano in the world. Effects of eruptions: - volcanic ash (global temp.) Lava flows Fires Lahars (mudslides) Acid rain. Formation.
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What are volcanoes? • They are openings in the Earth that erupt gases, ash, and lava
Effects of eruptions: - volcanic ash (global temp.) • Lava flows • Fires • Lahars (mudslides) • Acid rain
Formation • Magma is forced upward towards the Earth’s surface (WHY?) • Flows out through openings called VENTS
Where do they occur? • Divergent Plate boundaries Iceland
Convergent plate boundaries Andes Mountains – South America
Hot Spots • The Hawaiian Islands
Types of Eruptions • Based on - amount of water vapor or other gases trapped in magma - Silica content of magma
Quiet Eruptions Basaltic magma Iceland Kilauea
Explosive Eruptions Granitic & Andesitic Magma Mt. St. HelensSoufriere Hills Mt. Pinatubo
Forms of Volcanoes Shield Volcano – quiet eruptions of basaltic magma layering to form broad volcanoes with sloping sides
Cinder Cone – Explosive eruptions of tephra which form steep sided, loosely packed volcanoes
Composite Volcano – A combo of quiet and violent eruptions usually steep