What is happening in this photograph??

What do volcanic eruptions reveal about the earth’s

interior??

What do you think the darker material floating on the molten

lava is??

Earthquakes and Volcanoes

Chapter 7

Section 1 Earthquakes

Objectives:› Describe what happens during an

earthquake› Explain the difference between an

earthquake’s focus and epicenter› Compare and Contrast the three

types of waves produced by earthquakes

Skills Warm-up

This Just In ……› Imagine you are listening to the

radio when the announcer says that a 5.8 earthquake has occurred in Alaska.

› How do earthquakes happen??› What does the 5.8 mean??

Earthquakes Movements of the

earth’s crust that occur when _______________and release stored _________

Energy quickly travels out in ________ from the point of breakage

Energy can ______ and ________ rock and soil

Most occur at depths less than ____________ because the rocks are brittle

Earthquakes Most earthquakes

result from movements of the earth’s crust along ___________

Faults are __________ in the earth’s crust

The 2 sides move in _________ _______

and earthquakes occur

Physics of Earthquakes As the 2 sides of a

fault move past each other, sometimes the rocks ________, _______ and become __________

Tremendous ________ builds up in these areas

Physics of Earthquakes ______ _____ – amount

of stress a material can absorb› Example – rubber

band stretched too far

When rocks are strained beyond elastic limit – _______ and ________ past each other

Huge amount of __________ released.

Physics of Earthquakes As rocks break and

move, __________ _______ is transformed into _______ _________

_______ ________ – the vibrations produced by earthquakes

3 Types:› ____________› ____________› ____________

Primary Waves P Waves – _________

seismic waves _____________ - the

material through which the wave is travelling moves in the _________ direction as the wave

___________________________the earth in direction of the wave

Secondary Waves S Waves - second

waves to arrive at a given point – _____ _________

__________ – material moves at ______ ________to the wave direction

Like the up-and-down movement of a rope

Surface Waves ____________– when P

and S waves arrive at earth’s surface

Cause the earth’s surface to __________ ____________________________________________________________

Cause the __________ damage during an earthquake

Activity Earthquakes movie

Focus vs. Epicenter _______ – area along a

fault where _________ ______ ______________ – where earthquake begins› Seismic waves travel

out in __________ from the focus

___________ – point on earth’s surface directly __________________ – strongest shakes felt here

Detecting Seismic Waves ________________ -

detect and record seismic waves

Have a pen attached to a weight and a sheet of paper on a revolving drum

Seismic waves cause the pen to _______ and record a wavy line on paper

_________ of the peaks indicates the _________ of the earthquake

Locating an Epicenter P, S, and L waves

travel at _________ _________

So, they reach a seismograph at __________ _________

The difference between the arrival times of the waves helps scientists find the _______________

Locating an Epicenter Calculated distance to

the epicenter becomes the ________ of a circle that is plotted on a map

Epicenter lies ______________ on the circle

Plotting circles from ___ ____________ _______ _________ pinpoints the epicenter – why do you need 3 stations??

Rating Earthquakes _______ _________–

compares the size of earthquakes using data from seismograph stations› Each increase of _____

magnitude number equals an increase of ______ in ground motion

› A magnitude 7 earthquake causes 10 times more damage than a magnitude 6 and 100 times more damage than a magnitude 5

Rating Earthquakes ________ ________–

measures the effects of an earthquake on › ________________› ________________› ________________› ________________

Data gathered from people who have experienced the quake are used to determine an intensity value for their location

Activity Comparing earthquake scales Textbook page 136

Earthquake Zones Most of the world’s

earthquakes occur along or near the edges of ________ ______________

At these spots, ______ is the greatest

3 Major earthquake zones:› 1. ________________› 2. ________________› 3. ________________

Ring of Fire Accounts for ______ of

world’s seismic activity

Goes all the way around the _________ _________

Includes east coast of Asia and west coasts of North and South America

Active spots in the U.S.› __________________› __________________

Mid-Atlantic Ridge Hypothesis – ________________

__________ is being made along the mid-Atlantic ridge

This causes many earthquakes

Mediterranean-Asiatic Belt

_____________ _________ are colliding

Causes very destructive _____________

Far from Plate Boundaries Small number of

earthquakes occur far from plate boundaries (strong)› ______________________

________________› ______________________

________________ Even quiet parts of

earth can conceal large amounts of ____________

Hidden Faults 1983 – Coalinga, Ca

(between LA and SF) Magnitude __________

earthquake Surprised scientists:

› __________________› __________________› __________________

Hidden Faults Team of scientists

studied what happened

Found several faults ___________ beneath

They were hidden inside of __________ in the earth

The determined these faults are ______ very active

Questions 1. Explain what causes earthquakes. 2. What is the difference between an

earthquake’s focus and epicenter? 3. How do the 3 types of seismic waves

differ? How are they similar? 4. Would using 4 seismograph stations

to locate the epicenter of an earthquake be any more accurate than using 3? Explain.

Lab Activity – How to Model the Richter Scale

Page 139 in Textbook

Section 2 EarthquakeEvidence

Objectives:› Describe some features produced by

earthquakes› Discuss factors that determine

earthquake damage› Explain what causes tsunamis› Make Inferences about ways to build

structures that could withstand major damage from earthquakes

Ground-Level Evidence Earthquake

evidence is sometimes preserved in ________ or ____________ changes to the ground

Strong earthquakes leave _________ evidence

Ground-Level Evidence At some faults changes

are _____ but ________________ – no earthquakes

____________ – slow, continuous, steady motion

Creep rate of 1 cm/year – ground levels would be displaced by 1 meter after __________

Can break structures

Landscape Evidence Powerful

earthquakes can cause ____________ damage

____________ earthquake of 1964 – ______ magnitude

Upheaval of >260,000 square km of ground

___________ moved sideways!

Landscape Evidence Earthquakes

affect poorly compacted sediments more:› __________› __________› __________

Slides Rapid down slope

movements of ________, ________, and _________

Can occur on a _______ or far away

Large sections of mountain may ________ and race downward

Some continue for ____________, destroying all in their paths (homes and roads)

Scarps Sudden earth

movements that _________ ________

Height depends on the _____ of material uplifted and the ___________ and ___________ of uplift

Fissures Long ________ in

rock or soil May extend for

_______ _____________

If fissures occur on hill or mountain – massive ____________ can occur

Factors of Earthquake Damage ____________ of

epicenter to ______________ area

Moderate quake in a crowded city causes _________ damage than a large quake in a desert

Factors of Earthquake Damage _______ ___ _________

where structures are built affects amount of damage

Soft, wet, loose soils can ___________ seismic waves

Buildings on more solid ground have better chance of survival

Factors of Earthquake Damage

Building ________ and _____________ affect damage

________ __________ buildings may move with and withstand ground motion

Brick and cement may ________ and _____________

Factors of Earthquake Damage __________ – an ocean

wave caused by ________________

__________ water – tsunamis are low and fast-moving

__________ water – they slow down and increase in height (30 meters)

Few structures survive a large tsunami

Earthquake Prediction Past – changes in

animal behavior and well levels

Now – seismologists look at› __________________› __________________› __________________

Loma Prieta Earthquake 1981- scientists

predict a quake is likely in the _____ _______mountains within ______ years

1988 and 1989 – moderate quakes identified as ___________

1989 – devastating earthquake in _______ ___________

Earthquake Safety If you live near an active fault – should

have an earthquake _______ ________› What to ______ during quake› Where to ________ after quake› How to ______________ if phones don’t work

In earthquake-prone areas – strict _________ ___ _________ laws are in place

Questions 1. What are some changes caused by

earthquakes? 2. What factors determine the amount

of damage caused by an earthquake? 3. Describe the hazards you might face

if an earthquake struck while you were:› asleep in bed› standing next to a tall building› at the beach› skiing

Activity Earthquake Webquest

Section 3Volcanoes

Objectives:› Describe how volcanoes form› Explain why volcanoes erupt› Compare the 3 main types of

volcanoes› Make a model of the structure of a

volcano

Skills Warm-up

Pressure Is Mounting› What happens when you blow up a balloon

or inflate a tire and put in too much air?› What happens when heat and pressure

build up in a closed space and the pressure is suddenly released?

› How might these pressure situations be similar to a volcano that is about to erupt?

Volcanoes Any opening in the

earth’s crust that has ________ _______ ______

Also, the mountain that builds up from _________ _________

Examples:› _______ – Japan› ______________ –

Washington state› _____________ - Sicily

Formation of a Volcano ________ (molten rock)

is under great ________ deep inside earth

Magma forms deep pockets called ________ ___________ in some places

If the __________ and _________ are great enough, magma will force its way up through earth’s crust

Formation of a Volcano The more heat and

pressure acting on magma – the more likely magma will force its way to the surface

_________ – magma that reaches the earth’s surface

__________ – when lava or other volcanic materials reach earth’s surface

Volcano Life ___________ – have

erupted in the past century

___________ – haven’t erupted in hundreds of years

___________ – haven’t erupted in thousands of years

Eruptive life may span _________ __ ________ ___ ______

Mount Popa - Myanmar

Parts of a Volcano _______ ___________ –

formed from large pockets of magma

When magma is hot or powerful enough, it makes its way toward the surface through ________ in the ________

Parts of a Volcano ________ – long, nearly

_______ ________ in the crust through which magma moves

Can be thousands of meters long and only a few meters wide

Magma travels through the pipe until it reaches a ________ on earth’s surface

Parts of a Volcano

__________ – steep, hollowed-out area surrounding a vent at the _______ of a volcano

Usually forms after a very _____________ eruption

Parts of a Volcano

________ – opening through which all volcanic material ________ ____ _______

Common at the tops of volcanoes, but may also be _______ ___ ________

Volcanic Eruptions Eruptions can be:

› __________________________________________

› __________________________________________

This is determined by:› __________________› __________________› __________________

Lava Flow _________ of lava that

flows from a vent Stream can be

_______ or spread out Some lava flows can

reach speeds of _________________

Lava cools and hardens as it moves

Example - __________

Volcanic Explosions Explosive volcanoes

give off ___________ _________

Debris is identified by ____________› Dust – size of flour

grain› Ash› Cinders› Bombs - > 64 mm

Activity

Types of Volcanoes Produced by

different types of volcanic eruptions and explosions

Named for its shape or structure:› __________________› __________________› __________________

Cinder Cone Volcanoes Form from the

products of _________ _____________

Ash, cinders, and other debris mound up around the vent, ___________ __ ______

Are ________ sloping at the top and _________ sloping at the base

Usually form from ____, ____________ magma

Shield Volcanoes Have ______, shield

like shapes Lava is _______ and

______ ______ away from the vent

As it cools down, it becomes thicker, slows down and collects.

Composite Volcanoes Contain alternating

layers of _________ _____ ____ _______

Usually formed from _______ ________ of eruptions

Have ______ tops but gently ___________ bases

Areas of Volcanic Activity Most earthquakes

and volcanoes occur along _______ ______________

Volcanic activity can often produce ___________________

As magma moves up, it may _________ rocks or ___________ overlying crust

Ring of Fire Encircles ______________ Major zone of both

_____________ and _______________

Ocean plates are ______________ and volcanoes occur in long chains

One major chain runs along the west coasts of _______ _____ _______ _____________

Oceanic Ridge Systems Earth’s _____________

volcanic zones Plates are moving apart

forming cracks called ___________

As magma rises through rifts, the _______________

Lava builds up forming underwater ___________

__________ is formed from volcanoes that have risen above the surface

Hot Spots Develop in parts of the

earth’s mantle that are _______ _____

They can be _______ from plate boundaries

As the hot spots melt the surrounding rock, the rock changes to _________ and rises to the surface

_________ ________ are formed over a hot spot

Great Vesuvius Eruption ________ __________ is

the only active volcano on the European mainland

It is located just outside _______, _______

It last erupted in ____ Most destructive

eruption was on August 24, AD. 79

Great Vesuvius Eruption Most people

probably didn’t know that the mountain was a volcano

It hadn’t erupted in _______________

But there was a ________ earthquake 17 years earlier

Great Vesuvius

Eruption Eruption rained hot

ash, mud, and stones on the residents of _____________

Many people did not survive – _______ ______

Town disappeared completely under _____ __________of ash and stone

Wasn’t rediscovered for ___________ years

Life on a Volcanic Island How does life develop on molten

rock? Moisture from _______ and ______

react chemically with exposed _________

Over time, ________ develops Wind, waves, and birds scatter

________, ______________ and _________

________ and _________ appear and break down rock

Ocean currents bring _________ life

Eventually there will be a ____________ of plants and animals

Surtsey, Iceland

Predicting Volcanic Eruptions

Sophisticated devices can monitor:› __________

accumulation› increased __________

activity› changes in

________________› gas ____________

Advances in photography and satellite imaging

Questions 1. What is a volcano? How does it

form? 2. Explain the differences between

shield volcanoes, cinder cones, and composite volcanoes.

3. Volcanic activity has been known to trigger tsunamis. How is this possible?

4. Draw a general diagram of a volcano. Label its main parts.

Activity Volcano Webquest

Activity Review sheets – quiz grade