Section 9 2 Volcanic Eruptions What FACTORS determine

Section 9. 2 Volcanic Eruptions

What FACTORS determine if a volcano erupts violently or quietly?

Quiet eruptions Hawaii & Iceland https: //www. youtube. com/watch? v=fm. CJS S 2 YAP 0

Explosive, violent eruption https: //www. youtube. c om/watch? v=Ih. U 6 jml 6 NY 4

Page 121 Felsic magma Feldspar, silica Mafec* magma magnesium and iron

Which has a HIGH viscosity? Resistance to flow honey water

FELSIC magma • Light colored minerals: • Quartz, orthoclase Feldspar • More than 60% silica • HIGH viscosity MAFIC magma • Dark colored minerals: • Magnesium and iron Fe • Olivine, pyroxene, Hornblende, augite, biotite • Less than 50% silica • LOW viscosity

Geode CD-ROM Lesson 1. Nature of Volcanic Eruptions And Lesson 2. Materials Extruded During Volcanic Eruptions

Bell-work Pyroclastics consist of …… Ash Cinders Lapillii Glass Pumice Bombs Blocks Tuff (welded ash) -

Bell-work 4. What is 1 difference and 1 similarity between a … Pyroclastic flow and a Lahar

Volcanic Explosivity Index How to measure a volcanic eruption

Paroxysmal • a sudden outburst of a violent eruption • an increase of periodic eruptions • An eruption with a (V. E. I. ) Volcanic Explosivity Index of 5 (on a scale of 0 -8)

Lava Vocabulary Quiz 9. 2 1. pyroclastic Hot, erupted glass, ash, and rock fragments. ________ 2. igneous All lava flows are this type of rock. ___________ 3. pahoehoe A basaltic lava that results in smooth, ropelike surfaces: ______ 4. silica Magma has a high viscosity because it contains over 70% of ____ 5. explosive If the magma has a high gas content, the eruptions tend to be ____ 6. felsic Because of their high silica content, this rock is light colored. ____ viscosity lava aa pahoehoe pillow lava pyroclastic ash silica cinders igneous metamorphic non-explosive mafic explosive sedimentary felsic

Before the 1980 eruption After the VIOLENT eruption The summit and side has been blown away.

A portion of the side of the mountain was “blown away” leaving the mountain less steep. Flatter terrain then before. *Construct the profile activity

“I was walking along a path with two friends – the sun was setting - suddenly the sky turned blood red I paused, feeling exhausted, and leaned on the fence - there was blood and tongues of fire above the blue-black fjord and the city my friends walked on, and I stood there trembling with anxiety - and I sensed an infinite scream passing through nature. " Edvard Munch

An agonized figure wails against a blood red Norwegian skyline in Edvard Munch's “The Scream” (1893) in the National Gallery, Oslo, Norway The 1883 eruption of the volcano Krakatoa in Indonesia put so much ash into the atmosphere, it caused unusually intense sunsets throughout Europe in the winter of 1883 -4, which Munch captured in his painting.

Based upon the description… 1. What type of volcano was this? shield, stratovolcano, cinder cone 2. What type of magma erupted? mafic or felsic 3. What type of plate boundary does this volcano lie on? Convergent, divergent, transform 4. What would the eruption be on the V. E. I.