logging in or signing up 10_Volcanoes aSGuest629 Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 65 Category: Science & Tech.. License: All Rights Reserved Like it (0) Dislike it (0) Added: October 09, 2008 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Volcanoes : Volcanoes Volcanoes : Volcanoes Evidence that we live in an active planet The gods of the underworld Millions of people live near active volcanoes The greatest geological hazard Mount Saint Helens- after : Mount Saint Helens- after Hazard : Hazard Future hazard : Future hazard Population near big, recently active volcanoes Seattle Mexico City Quito Indonesia Japan Lava : Lava Molten rock that flows on the surface Basaltic Lava low silica, fluid, low gas, not explosive Andesitic Lava high silica viscous gas-rich explosive Types of volcanoes : Types of volcanoes 1. Shield Volcanoes Hawaii, Iceland Basaltic 2. Stratovolcanoes (or composite) Mt. Saint Helens, Pinatubo, etc Andesitic Explosive Shield Volcanoes : Shield Volcanoes Huge broad cones Gentle slopes Made from lava flows Basaltic Form at hotspots Not very dangerous Predictable Stratovolcanoes(composite) : Stratovolcanoes(composite) Andesitic lava Rich in dissolved gases Violent eruptions alternate with lava flows Steep-sided cones Very dangerous Unpredictable Pyroclastic Flows : Pyroclastic Flows Product of explosive eruptions Hot ash shot up into the atmosphere Ash column collapses Pyroclastic flow can travel 60 mi/hr Ash can fall 100’s of miles away Ash may affect global climate Mt. Saint Helens before : Mt. Saint Helens before Phreatic (vapor) eruption : Phreatic (vapor) eruption Bulge : Bulge Mt. St. HelensPyroclasticEruption : Mt. St. HelensPyroclasticEruption After the eruption : After the eruption Lahars (mudflows) : Lahars (mudflows) Lahars (mudflows) : Lahars (mudflows) Very destructive Kill as many people as the eruption itself Loose ash forms mud avalanches Glaciers on top of volcano melt Rain Inside a volcanoe : Inside a volcanoe Slide 37: Pyroclastic eruption Volcanic landscape: A Caldera (Crater Lake) : Volcanic landscape: A Caldera (Crater Lake) Crater lake formation(caldera) : Crater lake formation(caldera) 1. Early eruptions from composite cone 2. Great eruption empties the magma chamber 3. Summit collapses 4. Caldera fills with water Slide 44: Plate Tectonic Settings of Volcanism Slide 45: Plate tectonic settings of volcanoes You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
10_Volcanoes aSGuest629 Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 65 Category: Science & Tech.. License: All Rights Reserved Like it (0) Dislike it (0) Added: October 09, 2008 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Volcanoes : Volcanoes Volcanoes : Volcanoes Evidence that we live in an active planet The gods of the underworld Millions of people live near active volcanoes The greatest geological hazard Mount Saint Helens- after : Mount Saint Helens- after Hazard : Hazard Future hazard : Future hazard Population near big, recently active volcanoes Seattle Mexico City Quito Indonesia Japan Lava : Lava Molten rock that flows on the surface Basaltic Lava low silica, fluid, low gas, not explosive Andesitic Lava high silica viscous gas-rich explosive Types of volcanoes : Types of volcanoes 1. Shield Volcanoes Hawaii, Iceland Basaltic 2. Stratovolcanoes (or composite) Mt. Saint Helens, Pinatubo, etc Andesitic Explosive Shield Volcanoes : Shield Volcanoes Huge broad cones Gentle slopes Made from lava flows Basaltic Form at hotspots Not very dangerous Predictable Stratovolcanoes(composite) : Stratovolcanoes(composite) Andesitic lava Rich in dissolved gases Violent eruptions alternate with lava flows Steep-sided cones Very dangerous Unpredictable Pyroclastic Flows : Pyroclastic Flows Product of explosive eruptions Hot ash shot up into the atmosphere Ash column collapses Pyroclastic flow can travel 60 mi/hr Ash can fall 100’s of miles away Ash may affect global climate Mt. Saint Helens before : Mt. Saint Helens before Phreatic (vapor) eruption : Phreatic (vapor) eruption Bulge : Bulge Mt. St. HelensPyroclasticEruption : Mt. St. HelensPyroclasticEruption After the eruption : After the eruption Lahars (mudflows) : Lahars (mudflows) Lahars (mudflows) : Lahars (mudflows) Very destructive Kill as many people as the eruption itself Loose ash forms mud avalanches Glaciers on top of volcano melt Rain Inside a volcanoe : Inside a volcanoe Slide 37: Pyroclastic eruption Volcanic landscape: A Caldera (Crater Lake) : Volcanic landscape: A Caldera (Crater Lake) Crater lake formation(caldera) : Crater lake formation(caldera) 1. Early eruptions from composite cone 2. Great eruption empties the magma chamber 3. Summit collapses 4. Caldera fills with water Slide 44: Plate Tectonic Settings of Volcanism Slide 45: Plate tectonic settings of volcanoes