Chapter 5: Earthquakes and Volcanoes Section 1 - Earthquakes.

Chapter 5: Chapter 5: Earthquakes and Earthquakes and

VolcanoesVolcanoes

Section 1 - EarthquakesSection 1 - Earthquakes

What causes earthquakes?What causes earthquakes?

When sudden energy is released When sudden energy is released from Earth’s crust breaking or from Earth’s crust breaking or moving which cause vibrations.moving which cause vibrations.

If the vibrations are large enough If the vibrations are large enough they are felt as they are felt as earthquakes. earthquakes.

What is a Fault?What is a Fault?

A A faultfault is a large is a large fracture in rock fracture in rock along which along which movement occurs.movement occurs.

The type of fault The type of fault that forms depends that forms depends on the forces on the forces applied to the rock.applied to the rock.

What are the three main types of faults?

Normal FaultReverse FaultStrike-Slip Fault

What are Normal Faults?What are Normal Faults?

When rocks are pulled apart under tension When rocks are pulled apart under tension forces.forces.

Along this fault, rock above the fault moves Along this fault, rock above the fault moves DOWN compared to rock below the faultDOWN compared to rock below the fault

What are Reverse Faults?What are Reverse Faults? Created when compression forces squeeze Created when compression forces squeeze

rocks together and rock above a fault rocks together and rock above a fault moves UP compared to the rock.moves UP compared to the rock.

Reverse Fault AnimationReverse Fault Animation

What are Strike-slip Faults?What are Strike-slip Faults?

Shearing forces Shearing forces cause rock to cause rock to move past each move past each other in other in opposite opposite directions along directions along Earth’s surface.Earth’s surface.

Strike Slip Fault AnimationStrike Slip Fault Animation

Where do earthquakes begin?

Inside the earth at the FOCUS.

What is a focus?What is a focus? The The focus focus is the point INSIDE Earth where is the point INSIDE Earth where

movement first occurs and energy is movement first occurs and energy is released.released.

What is an epicenter?What is an epicenter? The The epicenter epicenter is the point on Earth’s is the point on Earth’s

SURFACE located directly SURFACE located directly aboveabove the focus. the focus.

What are Seismic Waves?What are Seismic Waves?

Waves of energy Waves of energy that travel that travel awayaway from the focus in from the focus in ALL directions. ALL directions.

What are the three main types of seismic waves?

– Primary waves (P-waves)Primary waves (P-waves)– Secondary waves (S-waves)Secondary waves (S-waves)– Surface wavesSurface waves

What are Primary Waves (P-What are Primary Waves (P-waves)?waves)?

The first waves.The first waves. Travel the fastest through rock material.Travel the fastest through rock material. The rock particles move back and forth The rock particles move back and forth

in the same direction as the waves are in the same direction as the waves are moving.moving.

Primary Waves AnimationPrimary Waves Animation

What are Secondary Waves (S-What are Secondary Waves (S-waves)?waves)?

Next waves to occur after P-Next waves to occur after P-waves.waves.

Jiggle the rock through which Jiggle the rock through which they pass up and down and they pass up and down and from side to side.from side to side.

Secondary Waves AnimationSecondary Waves Animation

What are Surface Waves?What are Surface Waves?

Slowest and largest.Slowest and largest. Cause the most destruction.Cause the most destruction. Can vibrate side to side, sway or like Can vibrate side to side, sway or like

“waves of water” across land. “waves of water” across land.

Surface Waves AnimationSurface Waves Animation

Summarize your Cornell Notes Summarize your Cornell Notes notes:notes:

In AT LEAST five complete In AT LEAST five complete sentences, what did you sentences, what did you learn today?learn today?

How are Earthquakes How are Earthquakes Measured?Measured?

By a By a seismologist seismologist whowho is a scientist is a scientist that studies that studies earthquakes and earthquakes and seismic waves.seismic waves.

Using a Using a seismograph seismograph which which is the instrument is the instrument used to measure used to measure seismic waves.seismic waves.

How do seismologists locate How do seismologists locate the epicenter?the epicenter?

They look at the distance between the seismic waves They look at the distance between the seismic waves arrival times.arrival times.

Data from Data from at least threeat least three different seismograph stations. different seismograph stations. Where the points meet is where the epicenter is located.Where the points meet is where the epicenter is located.

What is magnitude?

The measure The measure of an of an earthquake’s earthquake’s strength. strength.

Earthquake in Japan, 1923

Before After

How is earthquake How is earthquake strengthstrength (magnitude) measured?(magnitude) measured?

Using the Using the The The Richter Scale Richter Scale which which measures the measures the earthquake’s earthquake’s magnitude.magnitude.

The scale ranges The scale ranges from 1-10; from 1-10; • 1 = weakest; 10 = 1 = weakest; 10 =

strongeststrongest• As each number

goes up, the strength increases by 10 and it releases 32 times more energy.

How is earthquake How is earthquake damagedamage measured?measured?

By the By the Modified Modified Mercalli intensity Mercalli intensity scalescale which which measures how much measures how much damage an damage an earthquake creates. earthquake creates.

The range of The range of intensities is intensities is represented by represented by Roman numerals. Roman numerals. • The range is from I (1)

to XII (12); I = least damage, XII = most damage

Earthquakes with Tim and Moby!

What are Tsunamis?What are Tsunamis?

Powerful seismic sea waves.Powerful seismic sea waves. Occur when an earthquake occurs on the ocean floor.Occur when an earthquake occurs on the ocean floor. Can travel outward from the epicenter in ALL directions.Can travel outward from the epicenter in ALL directions. When they approach land, the waves slow down and When they approach land, the waves slow down and

the height increases.the height increases.

Tsunamis with Tim and Moby!

What is seismic safe?What is seismic safe?

When a When a building will building will be able to be able to stand up stand up against against earthquake earthquake vibrations.vibrations.

How can we be seismic How can we be seismic safe?safe?

Retrofitting buildingsRetrofitting buildings Installing underground pipes Installing underground pipes

that can bendthat can bendBuildings standing on steel Buildings standing on steel

and rubber supportsand rubber supportsKeep away from all windows; Keep away from all windows;

avoid anything that may fall avoid anything that may fall on youon you

Can earthquakes be Can earthquakes be predicted?predicted?

Earthquakes are unique – Earthquakes are unique – no single change happens no single change happens to the Earth before an to the Earth before an earthquake strikes which is earthquake strikes which is why they are why they are almost almost impossibleimpossible to predict. to predict.

Summarize your Cornell Summarize your Cornell Notes:Notes:

In AT LEAST five complete In AT LEAST five complete sentences, what did you sentences, what did you learn today?learn today?

Chapter 5Chapter 5Section 2 - VolcanoesSection 2 - Volcanoes

What is a volcano?What is a volcano?

A cone shaped hill or mountain formed A cone shaped hill or mountain formed when hot magma, solids and gases erupt when hot magma, solids and gases erupt onto Earth’s surface through a vent.onto Earth’s surface through a vent.

What is magma?What is magma?

Molten rock Molten rock material material underunder the Earth’s the Earth’s surface. surface.

Magma can be Magma can be pushed upward pushed upward by rocks that by rocks that surround it.surround it.

How do volcanoes form?How do volcanoes form?

1.1. Layers of cooled, hardened Layers of cooled, hardened lavalava

2.2. Hot spotsHot spots

What is What is lava?lava?

Molten rock Molten rock materials materials aboveabove Earth’s Earth’s surface.surface.

What is theWhat is the

differencedifference

between lava andbetween lava and

magma?magma?

MagmaMagma is INSIDE the is INSIDE the

Earth and Earth and lavalava is is

OUTSIDE of the Earth.OUTSIDE of the Earth.

What is a crater?What is a crater?

Circular hole Circular hole at the top of a at the top of a volcano where volcano where lava and other lava and other volcanic volcanic materials are materials are released.released.

What is tephra?What is tephra?

Bits of rock Bits of rock or solid lava or solid lava that falls that falls from the air from the air after an after an eruption. eruption.

What is subduction?What is subduction? When two plates collide and the heavier plate sinks When two plates collide and the heavier plate sinks

below the lighter plate causing it to melt which below the lighter plate causing it to melt which forms a chamber of magma.forms a chamber of magma.

Occurs when an oceanic plate collides with a Occurs when an oceanic plate collides with a continental plate or when two oceanic plates collide. continental plate or when two oceanic plates collide.

What is a hot spot?What is a hot spot? Weak spots in the crust that allow magma to Weak spots in the crust that allow magma to

rise upward. rise upward. Hot spots are NOT located on plate Hot spots are NOT located on plate

boundaries.boundaries. The Hawaiian Islands formed because of a The Hawaiian Islands formed because of a

hot spot.hot spot.

Summarize your Cornell Summarize your Cornell Notes:Notes:

In AT LEAST five complete In AT LEAST five complete sentences, what did you sentences, what did you learn today?learn today?

What determines HOW a What determines HOW a volcano will erupt?volcano will erupt?

Some eruptions are violent and some have Some eruptions are violent and some have just slow flowing lava quietly down its just slow flowing lava quietly down its slopes….slopes….

The “ingredients” of the magma determines The “ingredients” of the magma determines what type of eruption will occur!what type of eruption will occur!– Lava that has more silica (oxygen and silicon) is Lava that has more silica (oxygen and silicon) is

thicker and slower.thicker and slower.– Lava that has more iron and magnesium and LESS Lava that has more iron and magnesium and LESS

silica flows easier and faster.silica flows easier and faster.– Water vapor and other gases can also affect Water vapor and other gases can also affect

eruptions. eruptions.

Types of VolcanoesTypes of Volcanoes

There are three major types of There are three major types of volcanoes:volcanoes:– Shield volcanoesShield volcanoes– Cinder cone volcanoesCinder cone volcanoes– Composite volcanoes or stratovolcanoesComposite volcanoes or stratovolcanoes

Shield VolcanoShield Volcano Largest type of volcanoLargest type of volcano Gentle, hilly slopesGentle, hilly slopes Formed by the build up of basaltic lava Formed by the build up of basaltic lava

layerslayers Slower lava flowsSlower lava flows

Shield Volcanoes (cont.)Shield Volcanoes (cont.)

Forms where magma is forced up from Forms where magma is forced up from deep in the Earth OR where plates are deep in the Earth OR where plates are diverging (separating) diverging (separating) – EXAMPLE: Mauna Loa, Hawaii which is the EXAMPLE: Mauna Loa, Hawaii which is the

largest active volcano on Earth. largest active volcano on Earth.

Cinder Cone VolcanoesCinder Cone Volcanoes Relatively small volcanoes usually Relatively small volcanoes usually

less than 300 meters tall.less than 300 meters tall. Often form in a group near other Often form in a group near other

larger volcanoes.larger volcanoes.

Cinder Cone Volcanoes Cinder Cone Volcanoes (cont.)(cont.)

Formed by medium Formed by medium force of explosion of force of explosion of tephratephra

Once gas is released Once gas is released the eruption stopsthe eruption stops

Can have short Can have short powerful eruptions powerful eruptions or high eruptions or high eruptions

EXAMPLE: Sunset EXAMPLE: Sunset Crater, ArizonaCrater, Arizona

Composite Volcanoes Composite Volcanoes (Stratovolcanoes)(Stratovolcanoes)

Steep-sided Steep-sided volcanoes made of volcanoes made of alternating layers of alternating layers of lava and tephra.lava and tephra.

Sometimes erupting Sometimes erupting violently, releasing violently, releasing large amounts of large amounts of ash and gas, which ash and gas, which forms a tephra layer forms a tephra layer of solid materials.of solid materials.

Composite Volcanoes Composite Volcanoes (cont.)(cont.)

Then a “quieter” Then a “quieter” eruption forms a eruption forms a lava layer.lava layer.

Forms when one Forms when one plate subducts plate subducts beneath another.beneath another.

Most common type Most common type of volcanoof volcano

EXAMPLE: Mount St. EXAMPLE: Mount St. Helens, Washington Helens, Washington

Fissure EruptionsFissure Eruptions

Fissure – cracks in Earth’s surfaceFissure – cracks in Earth’s surface Magma that is highly fluid Magma that is highly fluid

(watery) can ooze from fissures (watery) can ooze from fissures and form lava plateaus.and form lava plateaus.

Chapter 5Chapter 5Section 3 – Earthquakes, Section 3 – Earthquakes,

Volcanoes, and Plate Volcanoes, and Plate TectonicsTectonics

Pacific Ring of FirePacific Ring of Fire The Pacific Ocean is The Pacific Ocean is

almost completely almost completely surrounded by surrounded by volcanoes.volcanoes.

This ring is thousands This ring is thousands of miles long and of miles long and contains hundreds of contains hundreds of volcanoes.volcanoes.

80% of all earthquakes 80% of all earthquakes and volcanoes happen and volcanoes happen in the Ring of Fire. in the Ring of Fire.

Ring of FireRing of Fire

Summarize the notes:Summarize the notes:

In AT LEAST five complete In AT LEAST five complete sentences, what did you sentences, what did you learn today?learn today?