Welcome to Science 10/25 Get out your lab sheet. You have 3 minutes to create the type of volcano listed on your card. Have your group help you if needed. Today’s Schedule 1. Finish/Review Volcano Types Lab 2. Outline/Notes Volcanic Eruptions 3. Yokum Construction Co. will be open for business to sell building materials.

Volcano Types Shield, Cinder-Cone, and Composite. What causes these different types of volcanoes to form? The different ways in which they erupt and the different materials that are erupted.

Volcanic Eruptions Section. 3

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I. Kinds of Volcanic Eruptions Eruptions are classified as either quiet or explosive. How a volcano erupts depends on the gasses, silica, and viscosity of the magma. Silica-similar to sand, one of the key components of magma Viscosity- the resistance of a liquid to flow

II. How the Eruption Works A volcanic eruption is similar to an exploding pop can. Gasses inside the volcano build up. As gas builds up, so does the pressure. When the pressure is too great, the volcano erupts. BBC NEWS | Science/Nature | Animated guide: Volcanoes OUR RESTLESS PLANET

III. Quiet Eruptions Magma has low silica, low viscosity, and low gasses so it flows easily. Hawaiian Islands were made this way. OUR RESTLESS PLANET What type of volcano is formed by quiet eruptions? Shield

IV. Explosive Eruptions Magma has high-silica and high viscosity, making it thick and sticky. High Gas. Magma does not flow. Builds up in the pipe like a cork in a bottle. Pressure builds up until the volcano explodes. :: Make a Volcano

Mount St. Helens mt. st. helens - Google Videos# During Eruption

Mount St. Helens Before Eruption After Eruption "Mt. Saint Helens' Powerful Erruption"

Mt. St. Helens 2003 Mt. St. Helens 1984

V. Explosive Eruptions Explosive eruptions break lava into fragments that quickly cool into pieces of different sizes. Large pieces = bombs Small pieces = cinders Pyroclastic flow- mixture of hot gas, ash, cinders, and bombs -pyroclastic-flow-video.htm

VI. Stages of Volcanic Activity Active, dormant, or extinct? Active- erupting or shows signs of erupting. Dormant- may awaken in the future. Extinct- unlikely to erupt again Is a volcano ever really extinct? No, at anytime a volcano thought to be extinct could reawaken.

How It All Starts Magma from the mantle rises up through the crust because it is less dense. Magma becomes trapped beneath layers of rock. Weak spots in the crust allow trapped magma to reach the surface, forming a volcano.

At the Surface Magma Chamber- pocket of magma beneath a volcano Pipe- long tube that connects the magma chamber to the surface Vent- opening where molten rock and gas leave the volcano Pipe, Vent, Magma Chamber, Crater, Lava Flow

At the Surface Lava flow- area covered by lava as it pours out of a vent. Crater- bowl shaped area that may form at the top of a volcano.

Question of the Day Correctly the match the stages of volcanoes with the definitions. A. A volcano that is unlikely to erupt again. B. A volcano that is erupting or shows signs of erupting. C. A volcano that may awaken in the future Active Dormant Extinct

Today’s Objectives 1. Question of the Day 2. Open book quiz 3. Continue research on volcanoes