Section 9.2 Volcanic Eruptions

“the Scream” by Edvard Munsch is about volcanoes and the ash it emiited into the atmosphere that traveled for thousands of miles and months

What FACTORS determine if a volcano erupts violently or quietly?

Quiet eruptions Hawaii & Iceland https://www.youtube.com/watch?v=fmCJSS2YAP0

Explosive, violent eruption https://www.youtube.com/watch?v=IhU6jml6NY4

Felsic magma Mafec* magma Page 121 Felsic magma Mafec* magma Feldspar, silica magnesium and iron Expolsivity depends on the amount of silica and gas in the magma.

Which has a HIGH viscosity? Resistance to flow honey The more Viscous the magma, the more it resists flowing out of the volcano, the more explosive the eruption water

FELSIC magma HIGH viscosity MAFIC magma LOW viscosity 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 …… - Cinders Lapillii Glass Pumice 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 There is the Fajita scale for tornadoes, the Safiir-Simpson scale for hurricanes, Richter scale for earthquakes, and the VEI scale for volcanoes

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 pyroclastic Hot, erupted glass, ash, and rock fragments. ________________ All lava flows are this type of rock. _____________________ 3. A basaltic lava that results in smooth, ropelike surfaces: ____________ Magma has a high viscosity because it contains over 70% of ________ If the magma has a high gas content, the eruptions tend to be ________ Because of their high silica content, this rock is light colored. ________ viscosity lava aa pahoehoe pillow lava pyroclastic ash silica cinders igneous metamorphic sedimentary non-explosive mafic explosive felsic igneous pahoehoe silica explosive 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… What type of volcano was this? shield, stratovolcano, cinder cone 2. What type of magma erupted? mafic or felsic What type of plate boundary does this volcano lie on? Convergent, divergent, transform What would the eruption be on the V.E.I.