Eosc 114 Review Notes
Autor: walker43 • February 28, 2016 • Course Note • 2,454 Words (10 Pages) • 742 Views
Volcanoes
Volcanology Overview #1:
Facts:
-Some volcanic eruptions create their own weather; A Plinian eruption not only blows ash to great heights but also volcanic gases.
-Any gravity pulled mass movements of muddy volcanic debris are known as lahars.
Basalt (hottest) | Andesite (hot) | Rhyolite (less hot) | |
Volume of Earth’s Surface | 80% | 10% | 10% |
SiO2 content | 45-55% | 55-65% | 65-75% |
Viscosity | Low | Medium | High |
Eruptive Style | Peaceful | Medium | Explosive |
- Define the Science of Volcanology
Speculations (types):
-Active
-Dormant
-Extinct
-Oceanic volcanoes are relatively peaceful whereas subduction-zone volcanoes are explosive and dangerous
- Establish 2 ways that we study volcanoes?
- Study & Monitor Active Systems
- Forensic Reconstruction
- Define magma, lava, and volcano, and understand how they work
Magma: Melted rock in the Earth, below the Earth’s surface. Melt + crystals+ bubbles.
Lava: Melted rock exposed at the Earth’s surface: melt+crystals+bubbles
Volcano: Structure where magma is erupted at Earth’s surface, includes erupted products, all shapes and sizes, diverse compositions, Subaerial and Sunaqueous
How they form: Magma is created by the melting of preexisting rock in the Earth’s interior (mantle & crust). It reaches the surface through fractures and erupts as lava or as pyroclastic material (tephra).
- Introduce the concept of a Volcanic System:
Source Region→ Transport Region→Storage Region→Eruption Region
Source Region:
-The mantle
Transport Region:
-The Crust
-Magma channels and moves along cracks in the Earth’s crust forming dikes and sills. A dike is a vertical intrusion of magma and a sill is a horizontal intrusion of magma.
Storage Region:
-The Crust
-Magma chamber and magma ponds below the Earth’s surface in large chambers
-Magma that freezes in the crust and is not erupted is called intrusive rock
Eruptive Region:
-Surface volcanoes
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