GLG 101 - Physical GeologyGLG 101 - Physical Geology Bob LeightyBob Leighty

VolcanoesVolcanoes

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!Explore and have fun!

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.

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?What Controls Eruptions?VolcanoesVolcanoes

Felsic lavas are more viscous

(higher wt% SiO2, lower T = high viscosity = more

“sticky”)

Magma composition

Mafic lavas are more fluid

(lower wt% SiO2, higher T = low viscosity = flow easily)

> Viscosity strongly influenced by wt% SiO2,

temperature, etc.

(more explosive

eruptions)

(less explosive eruptions)

What Controls Eruptions?What Controls Eruptions?VolcanoesVolcanoes

http://www.mc.maricopa.edu/dept/d43/glg/Study_Aids/VolcanoReview_2004.pdf

Volcanism Review TableVolcanism Review TableVolcanoesVolcanoes

Current volcanic eruptions

http://volcano.und.nodak.edu/vwdocs/current_volcs/current.html

Volcanoes of the WorldVolcanoes of the WorldVolcanoesVolcanoes

Flood BasaltsFlood BasaltsVolcano TypesVolcano Types

VolcanoesVolcanoes

Flood BasaltsFlood BasaltsVolcano TypesVolcano Types

VolcanoesVolcanoes

Deccan Traps (India)

Columbia River (USA)

Flood BasaltsFlood BasaltsVolcano TypesVolcano Types

VolcanoesVolcanoes

Shield VolcanoesShield VolcanoesVolcano TypesVolcano Types

VolcanoesVolcanoes

Mauna Loa (USA)

Fernandina (Galapagos Islands, Ecuador)

Shield VolcanoesShield VolcanoesVolcano TypesVolcano Types

VolcanoesVolcanoes

Joes Hill (AZ)

~11 Mya

Arlington Mesa (AZ)

1.3 Mya

Shield VolcanoesShield VolcanoesVolcano TypesVolcano Types

VolcanoesVolcanoes

Cinder/Scoria ConesCinder/Scoria ConesVolcano TypesVolcano Types

VolcanoesVolcanoes

Cerro Negro (Nicaragua)

Paricutin (Mexico)

Cinder/Scoria ConesCinder/Scoria ConesVolcano TypesVolcano Types

VolcanoesVolcanoes

Sunset Crater (AZ)SP Crater (AZ)

71,000 years ago 800 years ago

Cinder/Scoria ConesCinder/Scoria ConesVolcano TypesVolcano Types

VolcanoesVolcanoes

StratovolcanoesStratovolcanoesVolcano TypesVolcano Types

VolcanoesVolcanoes

Mt. Saint Helens (WA, USA) Mt. Fuji (Japan)

Mount Mayon (Philippines)Popocatapetl (Mexico)

StratovolcanoesStratovolcanoesVolcano TypesVolcano Types

VolcanoesVolcanoes

500 Kya

San Francisco Peaks (AZ, USA)

StratovolcanoesStratovolcanoesVolcano TypesVolcano Types

VolcanoesVolcanoes

Lava DomesLava DomesVolcano TypesVolcano Types

VolcanoesVolcanoes

Mount Unzen (Japan)

Mount Saint Helens (WA, USA)

Lava DomesLava DomesVolcano TypesVolcano Types

VolcanoesVolcanoes

Sugarloaf Mountain (AZ, USA)

Elden Mountain (AZ, USA)

Lava DomesLava DomesVolcano TypesVolcano Types

VolcanoesVolcanoes

CalderasCalderasVolcano TypesVolcano Types

VolcanoesVolcanoes

Yellowstone (WY, USA) Long Valley (CA, USA)

Valles (NM, USA) Krakatau (Indonesia)

CalderasCalderasVolcano TypesVolcano Types

VolcanoesVolcanoes

Superstition Mountains (AZ, USA)

Chiricahua Mountains (AZ, USA)

CalderasCalderasVolcano TypesVolcano Types

VolcanoesVolcanoes

WWW Links in this LectureWWW Links in this Lecture

> 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

VolcanoesVolcanoes