Presentation on theme: "CH. 10.1 The Nature of Volcanic Eruptions Roots: Dyn = energy (dynamic) Dys = bad (dysfunction) e- = away (eject) Ego = self (egotistic) Em = cover with."— Presentation transcript:
CH The Nature of Volcanic Eruptions Roots: Dyn = energy (dynamic) Dys = bad (dysfunction) e- = away (eject) Ego = self (egotistic) Em = cover with (empower) Endo = inside (endocrine) Enn = years (perennial) En = inward (enclose) Epi = among (epidemic) Equi = equal (equivalent)
10.1 The Nature of Volcanic Eruptions May 17th 1980 Mt St Helens May 18th 1980 Mt St Helens May 19th 1980 Mt St Helens May 18th 1990 Mt St Helens
Volcanoes from Every Angle Volcanoes: Some Understanding (Flash: Volcanoes Mtns of Fire 27:00) Volcanoes: Cultures (Flash: Volcano Village Pride 2:49) Volcanoes: Out There (Flash: Volcano Olympus Mons 0:50) Volcanoes: The Big One (Flash: Volcano What Are the Odds 2:52)
Factors Affecting Eruptions Viscosity = a substance’s resistant to flow The viscosity of magma as it rises inside the volcano can affect the type of eruption. High Viscosity = slow moving = explosive eruptions Low Viscosity = faster moving = quieter eruptions Types of Viscosity in Lava age01.cfm?chapter_no=visualization
Factors Affecting Eruptions Dissolved Gases = gases trapped in magma Vent = opening to the surface Gases provide the force to eject magma from the vent. Gases are mostly water vapor and carbon dioxide (just like in a carbonated drink). High viscosity magma holds the gases until they explode out. Low viscosity magma lets the gases escape easily so they just bubble out. Volcanic Gases bubbling out. volcanic-gases-bubbling-out-of-an-undersea
Volcanic Material Lava Flows Melted basaltic rock flows quickly (about meters per hour). Smooth “skin” with wrinkles. Pahoehoe flow - looks like twisted and braided rope. aa flow – rough, jagged blocks with sharp edges. Melted rhyolitic rock flows very slowly. Pahoehoe Flow aa Flow
Volcanic Material Gases Gases are held in the magma under pressure. When the pressure is released the gases escape. Common gases usually include water vapor, carbon dioxide, sulfur, nitrogen, and a little chlorine, hydrogen, and argon. Sulfur gases can be easily detected from their “rotten egg” odor.
Volcanic Material Pyroclastic Materials Particles produced in volcanic eruptions. Vary in size from fine dust and ash to pieces weighing several tons. Cinders = small sized Lava blocks = large sized already hardened Lava bombs = large sized still glowing HSW: Volcanoes: Pyroclastic Flow Time: 02:29 Assignment Discovery: Pompeii's Destruction Time: 02:51 HSW: Surviving Montserrat Time: 04:04
Pyroclastic Materials Mt St Helens
Anatomy of a Volcano afp/VolcanEN1605/start.swf Ash Cloud Cinders Vent Lava Bomb Pyroclastic Cloud Pyroclastic Material Flank Eruption Magma Chamber Conduit Crust
Types of Volcanoes
Shield Volcanoes Produced by the accumulation of fluid basaltic lava. Broad,slightly domed structure. Examples are Hawaiian Islands and Iceland. OregonHawaii California Low amount of gases.
Types of Volcanoes Cinder Cones Made of cinders that harden in the air. Steep-sided sloping structure. Examples are on Hawaiian Islands and in California. High amount of gases. Hawaii California
Types of Volcanoes Composite Cones/Stratovolcanoes Made of layers of lava and pyroclastic deposits. Large, symmetrical cone structure. Examples are all around the Ring of Fire. High amount of gases. Fujiyama, JapanMt Shasta, CA Alaska Mt. Pelee, W. Indies
Types of Volcanoes Dangers from Composite Cones Pyroclastic FlowsLahars (Mudflows) Pompeii Indonesia
Caldera Formation: Caldera = large depression in a volcano
Calderas PhillipinesAlaska Oregon Iceland
Volcanic Necks and Pipes Pipe = long hole through which magma moves Neck = what’s left when the outside of the pipe erodes away leaving the solidified rock inside standing.
Volcanic Necks and Pipes Wyoming Chile New Mexico Burma
Lava Plateaus = large, flat landforms resulting from lava flow extruding from multiple fissures. See pg 288 Fig 9B. Hawaii Japan Yellowstone Italy