chapter 6 volcanoes and related hazards
DESCRIPTION
Chapter 6 Volcanoes and Related Hazards. Volcanic Eruptions Mild or Violent. Why do volcanoes erupt so differently Mt. St. Helens – violent Hawaiian Islands - mild. Viscosity & Eruptions. Composition Temperature Dissolved Gasses. Viscosity. Viscosity. Measure of resistance to flow - PowerPoint PPT PresentationTRANSCRIPT
Nevado del Ruiz, Columbia - 1985
•Erupts every 100+ years•130’ tall mudflows moving 30 mph•Buried Armero (45 miles away) at midnight•23,000 of the 28,700 citizens died
Volcanic ActivityNot Random- Plate Tectonics & Hot SpotsViolent
High viscosityContinental -AndesiteHigh gas content
MildLow viscosityOceanic - BasaltLow gas content
Volcanic Hazards
High ViscosityGlobal HazardsClimatic conditionsAir traffic
Low ViscosityLocal HazardsLava flows
Volcanic Hazards
Volcanic Ash
Dissolved Gases
Water Vapor - H2O
Carbon Dioxide - CO2
Sulfur Dioxide - SO2
Development of Pyroclastic Flows
Shield Volcanoes
Cinder Volcano
Composite VolcanoMount Shasta in California
Hot Spot Volcanoes
Caldera VolcanoesYellowstone & Toba
Profiles of Volcanoes
Mt. St. Helens Prior to the 1980 Eruption
Mt. St. Helens after the 1980 eruption
Mt. St. Helens
Plate Tectonics & Igneous Activity
Igneous activity is not randomMost volcanoes are in/near oceansBasaltic rocks = oceans & continentsGranitic rocks = continents
Volcanoes of the Cascade Range
World’s Major Volcanoes
Predicting Volcanic ActivityStudy the historyTopographic changesSeismic activityIncreased gasesGroundwater changes
End of Chapter 6