Volcanoes Bob Leighty GLG 101 - Physical Geology

These notes and web links are your primary “lecture” content in this class. Additionally, various articles are assigned each week to supplement this “lecture” information. I believe you’ll have enough information to reference without having to purchase a costly textbook. These lecture notes are very similar to the ones I use in my traditional classes. You’ll find they are loaded with imagery and streamlined text that highlight the most essential terms and concepts. The notes provide a framework for learning and, by themselves, are not meant to be a comprehensive source of information. To take advantage of the global knowledge base known as the Internet, I have included numerous hyperlinks to external web sites (like the Wikipedia, USGS, NASA, etc.). Follow the links and scan them for relevant info. The information from linked web sites is meant to supplement and reinforce the lecture notes – you won’t be responsible for knowing everything contained in them. As a distance learning student, you need to explore and understand the content more independently than in a traditional class. As always, I will help guide you through this learning adventure. Remember, email Dr. Bob if you have any questions about today’s lecture (rleighty@mail.mc.maricopa.edu). Leave no questions behind! Explore and have fun!

What Controls Eruptions? Volcanoes What Controls Eruptions? Amount of gas (water) in the magma > As magma rises, P decreases & water turns to steam that can propel the eruption > More gas (water) = more explosive > Less gas (water) = less explosive

What Controls Eruptions? Volcanoes Magma composition > Viscosity strongly influenced by wt% SiO2, temperature, etc. Mafic lavas are more fluid (lower wt% SiO2, higher T = low viscosity = flow easily) (less explosive eruptions) Felsic lavas are more viscous (higher wt% SiO2, lower T = high viscosity = more “sticky”) (more explosive eruptions)

Volcanism Review Table Volcanoes Volcanism Review Table http://www.mc.maricopa.edu/dept/d43/glg/Study_Aids/VolcanoReview_2004.pdf

Volcanoes of the World Volcanoes Current volcanic eruptions http://volcano.und.nodak.edu/vwdocs/current_volcs/current.html

Volcanoes Volcano Types WWW Flood Basalts

Volcanoes Volcano Types Flood Basalts

Volcano Types Flood Basalts Volcanoes Columbia River (USA) Deccan Traps (India)

Volcanoes Volcano Types WWW Shield Volcanoes

Fernandina (Galapagos Islands, Ecuador) Volcanoes Volcano Types Shield Volcanoes Mauna Loa (USA) Fernandina (Galapagos Islands, Ecuador)

Volcano Types Shield Volcanoes ~11 Mya 1.3 Mya Volcanoes Joes Hill (AZ) ~11 Mya Arlington Mesa (AZ) 1.3 Mya

Volcanoes Volcano Types WWW Cinder/Scoria Cones

Cerro Negro (Nicaragua) Volcanoes Volcano Types Cinder/Scoria Cones Cerro Negro (Nicaragua) Paricutin (Mexico)

Volcano Types Cinder/Scoria Cones 71,000 years ago 800 years ago Volcanoes Cinder/Scoria Cones SP Crater (AZ) Sunset Crater (AZ) 71,000 years ago 800 years ago

Volcanoes Volcano Types WWW Stratovolcanoes

Volcano Types Stratovolcanoes Volcanoes Mt. Saint Helens (WA, USA) Mt. Fuji (Japan) Popocatapetl (Mexico) Mount Mayon (Philippines)

San Francisco Peaks (AZ, USA) Volcanoes Volcano Types Stratovolcanoes San Francisco Peaks (AZ, USA) 500 Kya

Volcanoes Volcano Types WWW Lava Domes

Mount Saint Helens (WA, USA) Volcanoes Volcano Types Lava Domes Mount Saint Helens (WA, USA) Mount Unzen (Japan)

Volcano Types Lava Domes Volcanoes Sugarloaf Mountain (AZ, USA) Elden Mountain (AZ, USA)

Volcanoes Volcano Types WWW Calderas

Volcano Types Calderas Volcanoes Yellowstone (WY, USA) Long Valley (CA, USA) Valles (NM, USA) Krakatau (Indonesia)

Volcano Types Calderas Volcanoes Superstition Mountains (AZ, USA) Chiricahua Mountains (AZ, USA)

WWW Links in this Lecture Volcanoes > Viscosity - http://en.wikipedia.org/wiki/Viscosity > Mafic - http://en.wikipedia.org/wiki/Mafic > Felsic - http://en.wikipedia.org/wiki/Felsic > Volcanism review table - http://www.mc.maricopa.edu/dept/d43/glg/Study_Aids/VolcanoReview_2004.pdf > Current volcanic eruptions - http://volcano.und.nodak.edu/vwdocs/current_volcs/current.html > Flood Basalt - http://en.wikipedia.org/wiki/Flood_basalt > Shield volcano - http://en.wikipedia.org/wiki/Shield_volcano > Cinder cone - http://en.wikipedia.org/wiki/Scoria_cone#Cinder_cone > Stratovolcano - http://en.wikipedia.org/wiki/Stratovolcano > Lava dome - http://en.wikipedia.org/wiki/Lava_dome > Caldera - http://en.wikipedia.org/wiki/Caldera