New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

Chapter Five: Volcanoes

by: Lauren Sadowski

Chapter Five: Volcanoes GLY-125-001

Lauren Sadowski
Natural Hazards

Almost Ready


These notes were just uploaded, and will be ready to view shortly.

Purchase these notes here, or revisit this page.

Either way, we'll remind you when they're ready :)

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

The chapter on Volcanoes is huge; that being said this is only 2/3 of the notes.
Natural Hazards
Class Notes
25 ?




Popular in Natural Hazards

Popular in Department

This 6 page Class Notes was uploaded by Lauren Sadowski on Sunday October 11, 2015. The Class Notes belongs to GLY-125-001 at University of North Carolina - Wilmington taught by Nooner in Summer 2015. Since its upload, it has received 6 views.

Similar to GLY-125-001 at UNCW


Reviews for Chapter Five: Volcanoes


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 10/11/15
GLY125 Natural Hazards Chapter 5 Volcanoes 51 INTRODUCTION TO VOLCANISM Volcano activity is related to plate tectonics 23 of all the active volcanoes on earth are found around the ring of re because sinking plates at boundaries are mixing with magma Magma is the molted rock under the Earth but once it reaches the surface it is called lava Volcanoes form from different tectonic settings which makes every volcano different It is important to understand how the formation of magma and the plate tectonic settings affect volcanoes Knowing this information can understand the different types shapes and behavior of volcanoes HOW AND WHERE MAGMA FORMS I know this is going to be hard to forget since we were told this since elementary school but plate tectonics do not move around on a sea of magma Most magma comes from the asthenosphere Remember from previous chapters the asthenosphere is the weak layer in the mantle This ayer ows because it is close to the melting point This means that this layer is easier to melt than the layer above it the lithosphere There are three principle processes that create magma 1 Decompression melting Occurs when pressure exerted on hot rocks within the asthenosphere is decreased Decompression melting occurs and magma will begin to form even though the temperature stays the same You can nd this process predominately where Earth39s lithosphere is being stretched From chapter two we learned that the ocean ridges are constantly being stretched divergent bounda es The pressure of the planet is what keeps the magma in the center of the Earth however when the magma gets to close the surface the pressure is no longer as strong as it use to be and the magma pushes through the surface Also occurs with hotspots which are created by smaller decompression melting 2 Addition of volatiles lowers the melting temperature of rocks by breaking the chemical bonds within the minerals Volatiles are chemical compounds water carbon dioxide sulfur dioxide that evaporate easily and enter the atmosphere as gas Water and other volatiles enter as a uid to rocks that are close to the melting point and then the rock will begin to melt Magma formation from addition of volatiles are found at subduction zones which is what created the ring of re The Paci c Nazca Cocos Philippine and Juan de Fuca plates are sinking below tangent plates Volatiles that are trapped in the sediment on the sea oor are released as the plate is forced downward into the hotter mantle The volatiles play an important role in the behavior of a volcano 3 Addition of heat to rocks will caused them to melt if the temperatures rise above the melting temperature depending on their depth melts rocks as the magma moves through the mantle which creates more magma MAGMA PROPERTIES Magma is composed of the melted silicate rocks and other gases There are three types of magma that are differentiated by the amount of silica found in the magma gt Basaltic magma Most common type of magma Have relatively low silica contents 4555 perent Referred to as ma c in composition gt Rhyolitic magma Contains more than 65 percent of silica Referred to as felsic composition gt Andesitic magma ls intermediate in composition Contains 5565 percent silica Magma is less dense than rock which is why it oats to the surface and sometimes creates magma chambers that lay near the Earth39s surface Magma evolution is the processes of chemical changes magma goes through while rising to the surface VISCOSITY Greater amounts of silica make it more dif cult for lava to ow For those who are no familiar with viscosity it is the stickiness of a substance For an example honey has a higher viscosity that water Rhyolitic lava ows have high viscosity meaning it ows much slower It is normally restricted to the vent region and form steep domes Basaltic lava ows fast thin meaning it has low viscosity These differences affect the shape of the volcano The viscosity measures the severity of the eruption Obviously the fast moving lava is more dangerous than the slow moving lava Pyroclastic debris volcanic materials that are ejected from a volcano ash What to know for 51 1 What is magma and where does it come from 2 Describe the physical and chemical changes that cause rocks to melt 3 What is the relationship between plate tectonics and the location of volcanoes 4 What Is viscosity and what determines magma viscosity 5 Explain the relationship between magma composition viscosity and gas content 52 VOLCANO TYPES FORMATION AND ERUPTION BEHAVIOR Volcanoes are landforms that vary in size shape composition and eruptions Volcano Composition Volatile Shape Eruption Volcano Type Content Type Examples Stratovolca Andesite High Cone Combinatio Mount no or shaped with n of lava Shasta composite steep sides ows and Califronia cone built of lava pyroclastic Mount St ows and activity Helens pyroclastic Washington depos s Lava dome Andesite to Low to Dome Mostly Mount rhyolite moderate shaped effusive Lessen steep sided with lava39s California pilling up Mt Unzen near the dome Japan vent but can be explosive Shield Basalt Low Gentle arch Far Mauna Loa Volcano or shield traveling Hawaii shape with lava ows Kilauea shallow Hawaii slopes built up of many lava ows Cinder Cone Basalt Low to Cone Mostly SP Crater moderate shaped with tephra Arizona steep sides ejection Paricutin and summit lava ows Mexico crater Eldfell Iceland Continental Rhyolite High Broad uplift Tephra Yellowstone Calderas with large summit depression Craters Depression formed by explosion or collapse of volcano top 0 A few kilometes a mile in diameter Calderas 0 very lare crater formed from violent collapse of a cone 0 May be 20 or more kilometer in diameter and contain vents and hot sp ngs Vents Any opening for lava and debris 0 May be circular or thin ssures 0 Can produce ood basalts Hot springs Hot rocks heat groundwater The pressure pushes the water to the surface Geysers c When water is boiled underground and the steam explodes through the surface Caldera Eruptions Very rare extremely violent eruptions Produce a large amount of ash Referred to as the Supervolcano The last caldera eruption was at Yellowstone National park Volcanic Origins Mid ocean Ridges and Continental Rifts Basaltic magma directly form asthenosphere 34 of all lava extruded on earth If on land than shield volcanoes are formed Exampe Iceland at the Mid Atlantic Ridge Subduction zones composite comes are formed here most common along Paci c Rim Andesite magma with intermediate silica Over 80 percent of eruptions Exampe Cascade Mountains 0 Hot spots beneath the ocean basaltic magma forms shield volcanoes hot spots remain stationary Exampe Hawaii 53 GEOGRAPHIC REGIONS AT RISK FROM VOLCANOES Volcanoes are like earthquakes and are greatly affected by plate tectonics and most occur around the Ring of Fire But volcanoes can occur in other places due to other factors Hot spots Yellowstone park Or the volcanoes are on a midocean ridge So who is at risk Isolated areas of the US Southwest are at risk for volcano action because of Yellowstone National Park whereas the Eastern 23 of the US and Canada are safe from Yellowstone REMEMBER JUST BECAUSE THE EASTERN 23 OF US AND CANADA WILL NOT BE IMMEDIATELY AFFECTED BY THE VOLCANO BUT THE WORLD WILL BE AFFECTED BY THE ERUPTION 53 EFFECTS OF VOLCANOES Approximately 5060 volcanic eruptions each year around the world Most eruptions are harmless and cost little to no economic damage however when eruption take place near heavy populated areas the damage can be signi cant According to the book approximately 500 million people in the world live near volcanoes and with the population of humans only rising it is expected that more people will live near volcanoes Places such as Mexico Japan Philippines and Indonesia have the highest risk of Volcano eruptions Lava ow is one of the most familiar products of volcanic activity Pyroclastic activity the explosive volcanism in which magma and rocks that compose the volcano are blasted from a volcano vent and into the atmosphere Tephra pyroclastic debris Pyroclastic deposit when deposited hot tephra can be fused and form pyroclastic rock Ash fall occurs downwind of the volcano as the lighter ner particles are carried to the bottom of the volcano and rests on the Earth39s surface Ash falls cause lots of issues VVVV Crops are destroyed Water is contaminated by the particles and sediment from the volcano Buildings are damaged Health risks from drinkingeating contaminated food or breathing in gases ash sediment and particles from the volcanoes Pyroclastic ows debris from the volcano that ow 1 During the eruption ash is pushed into the air even though it has a higher density because of heat But will later settle after cooling Can still be hot when it reaches the ground and can start res destroy crops and buildings Lateral blasts form when the eruptions destroys a part of the volcano and magma starts leaking from the side of the volcano These are the fastest moving ows that destroy everything down the mountain Lava domes collapse most common volcanic process that causes pyroclastic ows Poisonous Gases The gases found in the debris of volcano are H20 water vapor C02 carbon dioxide H25 hydrogen sul de 502 sulfur dioxide H20 makes up 90 of the gases emitted from volcanoes


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Amaris Trozzo George Washington University

"I made $350 in just two days after posting my first study guide."

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."


"Their 'Elite Notetakers' are making over $1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.