Warm Up # 13 What is being shown in the picture on the left? What is being shown in the picture on the right? How do they relate to each other?

Warm Up While watching the Jimmy Buffett volcano song video, write down 3 things you think you know about volcanoes.

What is a VOLCANO? A volcano is a place where lava reaches the surface.

Anatomy of a Volcano Vent- where lava comes out. Crater – Bowl shaped depression around vent Caldera – really big crater (>30 miles wide)

What Comes Out of a Volcano? Lava: The term used for magma once it has erupted. Ash: Tiny fragments less than 2 mm Bombs: Big fragments of fluid or partially fluid lava or rock Tephra: Solid material of all sizes explosively ejected from a volcano into the atmosphere. Pyroclastic Flow: Clouds of ash, gases, and tephra that move down a slope at 160 mph! Very deadly! Gases: Carbon dioxide, steam, and sulfur dioxide, The gas carries dust so it looks like dark smoke. They can be very deadly! Mount Merapi, Indonesia

Magma – Mixture of molten (melted) rock, mineral grains (silica) and gases like water vapor deep beneath the Earth’s surface. There are 3 different types of Magma Magma

Types of Magma Viscosity – Internal Resistance to Flow High viscosity – flows slowly Low viscosity – flows fast Temperature affects Viscosity : Higher Temperatures = Lower Viscosity Composition affects Viscosity : More Silica and Gases = Higher Viscosity

Type of Magma Determines Type of Eruption Basaltic Magma – Same composition as Basalt rock (oceanic plates). Made from materials in the upper mantle. Low viscosity. Very small amounts of dissolved gases and Silica. Erupts quietly. Rhyolitic Magma– Same composition as Granite rock. Made from melted continental plates. High viscosity. Large amounts of dissolved gases and Silica. Erupts explosively. Andesitic Magma – Found where oceanic plates are subducted under continental plates. Intermediate amounts of Silica and gases. Intermediate eruptions.

There are three types of volcanoes: The type of volcano depends on the type of material that forms the volcano and the type of eruptions that occur.

Shield Volcano: A gently-sloped volcano. Broad, gently sloping sides and a circular base. Form when layers of basaltic lava accumulate during “gentle” eruptions. Example: Hawaiian Island Volcanoes – Mauna Loa

Cinder-Cone: A volcano made of cinders that are blown into the air. Forms when material is ejected high into the air and falls back to pile up around the vent. Very steep sides and are generally small (less than 1/3 mile high). Magma contains large volumes of gases and silica which makes them more explosive. They can be made from eruptions of andesitic or rhyolitic magma. Can form on the side of other volcanoes. Example: Izalco volcano in El Salvador

Composite or Stratovolcano: A volcano built of alternating layers of cinders and lava. Forms when layers of volcanic fragments (ash) alternate with lava. Magma contains large amounts of silica and gases. Much larger than cinder-cone volcanoes with moderately sloped sides. They are made from eruptions of rhyolitic magma. Violently explosive! Example: Mount St. Helens and Mount Rainier

What are the 3 types of magma and what kind of eruptions are they each responsible for? Warm Up #15