Download The Layers of Earth, Plate Tectonics, Volcanoes and Earthquakes

The Layers of Earth,
Plate Tectonics,
Volcanoes and
Earthquakes
Warm-up
•How do scientists know about
Earth’s interior even though they
have never seen the inside of the
Earth?
•Which part of the Earth is
broken into several large tectonic
plates?
Answer
• Scientists know though
studying seismic waves,
gravity, and earth’s
magnetism.
• The lithosphere is broken
into large plates.
Warm-up
• What is TRUE about the layer directly
below Earth’s plates?
• A. It is mostly solid rock
• B. It is mostly liquid rock
• C. It is mostly slightly softened rock.
GALLERY WALK
• You will be in groups of 2-3
students. You will rotate around
the room defining essential
vocabulary in your own words
using sticky notes. When you
have been to all words a whole
group discussion will take place.
Warm-up
• MEDIA CENTER/COMPUTER LAB
• Log in to
http://www.discoveryeducation.com/
• USER: wcp+ student ID (don’t use the plus)
• PASSWORD: Student ID
• Click on assignments, select Plate tectonics
and more assignment board. Complete all
activities and answer questions and fill out
chart on the dances with plates handout.
Warm-Up: Answer the following in
complete sentences:
Which of the following are part of earth’s plates?
– Continents but not ocean basins
– Ocean basins but not continents
– Both ocean basins and continents
Which of the following is TRUE about earth’s plates?
– They are separated by oceans.
– They are piled on top of one another within the earth.
– They fit closely together with each plate touching all
the plates that are next to it.
Warm-up
• Any last minute questions
before the vocab.
assessment? Please write
them down.
• If finished create a word wall
picture using one of the Earth
structure/plate tectonics
vocabulary terms or work on extra
credit.
Warm-up
• Name and define the 3 main
types of plate boundaries.
• What types of “natural
disasters” can occur at
these boundaries?
Review day
• Be ready for class-IN SEAT, PENCIL,
BINDER/NOTEBOOK
• Take out your completed study guide and
look over your answers and discuss with
ONLY your table partner (if you do not
have a table partner you may join another
group. ONLY discuss material on study
guide, you have 3 minutes after the bell.
Test day
• Be ready for the test, pencil, no
talking, quietly studying OR write
down any last minute questions.
• After the test: Pick up the Rock
cycle reading packet from the front
table. Read the article,
underline/highlight important
definitions and info., next complete
the attached handouts (follow
directions)
How do we know what the
Earth is made of?
• Geophysical surveys: seismic, gravity,
magnetics, electrical
Earth Layers
“Review”
• The Earth is divided into
four main layers.
*Inner Core
*Outer Core
*Mantle
*Crust
The Crust
* The Earth’s crust is like
the skin of an apple. It
is very thin compared
to the other three
layers.
*The crust makes up 1%
of the Earth.
* The crust of the Earth is
broken into many
pieces called plates.
• The Mohorovicic
Discontinuity, or
"Moho", is the
boundary between the
crust and the mantle.
The red line in the
drawing at right
shows its location. In
geology the word
"discontinuity" is
used for a surface at
which seismic waves
change velocity.
The Mantle
• The mantle is the
layer below the
crust.
• The mantle is the
largest layer of the
Earth.
• The mantle is
divided into two
regions: the upper
and lower sections.
Outer Core
* The core of the
Earth is like a ball
of very hot metals.
* The outer core is
liquid.
* The outer core is
made up of nickel
and iron (very
dense).
Inner Core
* The inner core of the
Earth has
temperatures and
pressures so great
that the metals are
squeezed together
and are not able to
move.
* The inner core is a
solid.
Lithosphere – the layer of earth
made of the crust and the rigid
rock of the upper mantle which
is broken into tectonic plates
Asthenosphere – the layer in
earth’s upper mantle directly
under the lithosphere in which
rock is soft and weak because it
is close to melting
Data Table
Name of Thickness
Layer
What Layer is
Made Of –
Consistency
Temperatur
e
Pressure
crust
6-70 km solid rock,
<870˚C
Low
mantle
~2,900
km
hot, but solid
material
870-
Medium
outer
core
~2,300
km
molten iron
and nickel
44006100˚C
High
inner
core
~2,400
km
solid iron
and nickel
7,0008,000˚C
Super
Intense
mostly granite
and basalt
4400˚C
Review
1) What are the four layers of the
Earth?
2) The Earth’s crust is very ______?
3) The mantle is the largest layer of
the Earth? True or False
4) Is the Outer Core a liquid or a
solid?
Answers!
1) Crust, Mantle, Outer Core, Inner
Core
2) Thin
3) True
4) Liquid
Plate Tectonics
If you look at a map of the world, you may notice
that some of the continents could fit together like
pieces of a puzzle.
Who is Alfred Wegener?
A German scientist who hypothesized the theory of
continental drift.
What is the Theory of
Continental Drift?
A hypothesis that all
the continents were
once joined together
in a single land mass
called Pangaea and
has since drifted apart.
Why wasn’t Alfred Wegner’s theory
accepted?
-Alfred Wegner had a lot of evidence to support
his theory, but...
He could not explain how the plates moved.
-Because he could not explain how the plates
moved, scientists did not accept his theory.
BUT his theory later developed into the theory
of plate tectonics…
WHAT IS THEORY OF PLATE
TECTONICS?
-The Earth’s crust is divided into 12 major plates which
are moved in various directions.
Pieces of Earth’s lithosphere are in slow, constant motion
-Movement is caused by convection currents in the
mantle.
-Plates move in three types of behavior:
This plate motion causes them to collide, pull apart,
or scrape against each other.
-Tectonic plates are made of
continental and oceanic crust
What evidence supports this
hypothesis?
1. Geology/Land Features:
-He noticed that the mountain ranges on the
continents of Africa and South America line up.
2. Fossils:
-Fossils-trace of an ancient organisms that has been
preserved in rock.
-Dinosaur fossils have been found in landmasses
separated by oceans.
3. Climate:
-Evidence of tropical plants has been found in the
Arctic Ocean and glacier evidence in South
Africa.
Plate Tectonics
• How Plates Move
• Diving between two plates
Pangaea – a hypothetical
supercontinent in which all
continents were once attached. It
began breaking apart about 200
million years ago
Convection – a process by which
energy is transferred to cause
warmer less dense air or liquid to
rise while the dense cooler liquid or
air is pushed down.
Tectonic plates – sections of Earth’s
upper layer that include both crust
and mantle material (lithosphere
broken into pieces).
Continental drift – a hypothesis that
Earth’s continents move on the
surface
Fault lines – a crack in Earth’s
surface
Earth’s Lithospheric Plates
Three Types of Plate
Boundaries
• Divergent
• Convergent
• Transform
What is a convergent boundary and
where does it occur?
-Place where two plates come together, or
converge.
-A “collision”
-Forms mountains and volcanoes
-When oceanic crust slips under continental
crust: SUBDUCTION -Subduction forms
volcanoes
Convergent Boundaries
There are three types of convergent plate
boundaries
1. Continent-continent collision
2. Continent-oceanic crust collision
3. Ocean-ocean collision
Continent-Continent
Collision Make Mountains
Himalayas
Continent-Oceanic Crust
Collision
Also called subduction, forms volcanoes
The ring of fire in the Pacific Ocean
is formed by subduction zones.
Ocean-Ocean Plate Collision
• Forms deep ocean trenches
• Mariana Trench in the Pacific is 11km deep!
What is a divergent boundary and
where does it occur?
-Place
where two plates spread apart; or diverge
-Molten material moves up
between the plates and forms
NEW ocean floor, rift valleys and
ocean trenches.
Divergent Boundaries
This map
shows the
age of the
oceanic
crust. The
red coloring
shows the
youngest
ages, whilst
the dark blue
shows the
oldest ages
(around 200
million years
old).
The divergent boundary runs straight through
Iceland….
What is a transform boundary and
where does it occur?
Where two plates slide past each other in
opposite directions.
Earthquakes occur when
two plates slide past each
other.
Transform Boundaries
San Andreas Fault
• Plate Tectonics in Action
Video
Volcanoes
A volcano is an
opening in the
Earth’s crust
through which
molten rock,
rock fragments,
and hot gases
erupt.
Volcanoes erupt many types of
materials:
• Magma
• Rock fragments
• Volcanic gases (mixture of water
vapor , carbon dioxide, and ashes)
• Pyroclastic flow – mixture of gases
and rock fragments that form a dense
cloud
Magma and Lava
Magma is molten rock BENEATH the
Earth’s surface. When magma
erupts, it is called lava.
Lava is molten rock, or magma that
reaches the Earth’s surface
through a volcano.
Magma Chambers
• Magma collects in areas called “magma
chambers”.
• Volcanic eruptions occur when a
chamber is not large enough to hold
additional magma that pushes in.
• Magma can remain in a chamber until it
cools, forming igneous (intrusive) rock,
or it can erupt in the form of lava.
Rock Fragments
Volcanic Gases
Volcanic gases
look like smoke
rising from the
volcano. They are
a mixture of ash
and gases (mostly
carbon dioxide).
Some volcanic
gases combine
with water in the
air to form acids.
Pyroclastic Flows
Sometimes volcanic gases can mix with
rock fragments forming a pyroclastic
flow. This is a dense cloud of superhot
gases and rock fragments that races
downhill. It can be as hot as 800°C
(1500°F) and can travel faster than 160
kilometers per hour (100 mi/h).
Pyroclastic flows are the most dangerous
type of volcanic eruption.
Formation of Volcanoes:
• Volcanoes are common along tectonic
plate boundaries where oceanic plates
sink beneath other plates.
• Volcanoes are also common along
tectonic boundaries where plates pull
apart, allowing magma to rise from the
mantle.
• Occasionally, volcanoes are formed over
a hot spot far from a plate boundary.
Volcanoes and their effects • Volcanic eruptions can knock down forests
and destroy homes by flowing into the
homes or by starting fires.
• Volcanic eruptions can clog rivers.
• Some volcanic gases combine with water in
the air to form acids.
• Many volcanic gases are dangerous. They
can make breathing difficult and damage the
lungs of people and animals.
• In West Africa, a sudden release of carbon
dioxide from a volcano at the bottom of a
lake killed 1700 people in 1986.
Lava FlowsMost lava moves
too slow to hurt
people. However,
it can knock
down, cover, or
burn nearly
everything in its
path.
Volcanic Ash • The weight of fallen
volcanic ash can cause
the roofs of buildings to
collapse.
• Ash makes roads
slippery, and it clogs up
machinery, including cars
and airplanes.
• Large amounts of falling
ash can suffocate plants,
animals, and people.
Mudflows • Mudflows are landslides
that occur when loose
rocks and soil are mixed
with water.
• Mudflows also form as
ash mixes into rivers
flowing from a volcano.
• Fast-moving mudflows
can bury entire towns
tens of kilometers from
an eruption.
Pyroclastic flows In 1902, a pyroclastic
flow from an
eruption in the West
Indies completely
destroyed the city of
Saint Pierre. Almost
30,000 people were
killed within a few
minutes.
Landslides Part of a volcano can
collapse and start a
landslide. The collapse
may be caused by an
eruption, an
earthquake, or even
heavy rainfall. A
landslide can cause a
tsunami if a large
amount of material falls
into the ocean.
Steam Explosions Steam explosions
occur when magma
comes into contact
with water. The entire
island of Krakatau
exploded in 1883,
causing a tsunami that
destroyed hundreds of
towns and killed more
than 36,000 people.
Steam explosions can
be devastating.
Long-Term Effects of Volcanoes:
• Volcanoes build as well as destroy.
Material erupted from volcanoes can
form new land. Over time, lava flows
can form new, rich soil.
• Repeated volcanic eruptions can build
a magnificent landscape of mountains
and valleys.
• People live in a volcanic area for its
natural beauty or there might be a
flourishing tourist industry such as
Hawaii.
Formation of Volcanic Islands
Questions!!!!!!!!!!
Answer the following questions -
• What are volcanoes?
• What is the difference between
“magma” and “lava”?
• What are the effects of volcanoes on
Earth’s land, water, and air?
EARTHQUAKES:
WHY? AND HOW?
EARTHQUAKES
sudden movement or shaking of the Earth
• Caused by plate tectonic stresses
• Located at plate boundaries
• Resulting in breakage of the Earth’s brittle crust
Earthquakes
▪ The waves travel in all directions.
▪ More than 1,000,000 occur a year or one
every 30 seconds.
▪ Earthquakes continue until all the energy
is used up.
▪ TSUNAMIS- Earthquakes on the ocean
floor: causing waves to become greater
than 20 meters high.
PLATE TECTONIC STRESSES
•
•
Plate boundaries and faults (= cracks where plate
sections are moving in different directions) cause
friction as plates move
Plates in a fault zone have STICK-SLIP motion
– Periods of no movement (stick)
and fast movement (slip)
– Energy stored as plates stick,
– Energy released as plates slip
EARTHQUAKE DAMAGE
• Landsides
• Building damage
• Liquefaction
Damage from Earthquakes
▪ Loss of life
▪ Can cause fires (broken natural-gas
lines, electrical power lines, or
overturned stoves)
Aftershocks
An aftershock is a smaller earthquake
that follows a more powerful
earthquake in the same area.
Sometimes structures weakened by an
earthquake collapse during shaking
caused by aftershocks.
LIQUEFACTION
when a solid (sand and soil) becomes
saturated with water and acts like a heavy liquid
• Results in a loss of soil strength & the ability of the soil to
support weight
ANIMATION OF
LIQUIFACTION
Click
EARTHQUAKE DAMAGE
Most caused by SURFACE waves (arrive
last)
Seismic Waves
Earthquakes produce three types of seismic
waves: primary waves, secondary waves,
and surface waves. Each type moves
through materials differently. In addition, the
waves can reflect, or bounce off boundaries
between different layers. The waves can also
refract, or bend as they pass from one layer
into another. Scientists learn about Earth’s
layers by studying the paths and speeds of
seismic waves traveling through Earth.
EARTHQUAKE WAVES
• FOCUS = place deep within the Earth and along the fault where
rupture occurs
• EPICENTER = geographic point
on surface directly above focus
• *SEISMIC WAVES produced by the release of energy
– move out in circles from the point of rupture (focus)
– 2 types: surface & body (travel inside & through earth’s layers)
• P waves: back and forth movement of rock; travel thru solid,
liquid, gas
• S waves: sideways movement of rock; travel thru solids
only
Focus and Epicenter
All earthquakes start
beneath Earth’s
surface. The focus of an
earthquake is the point
underground where
rocks first begin to
move. Seismic waves
travel outward from the
earthquake’s focus. The
epicenter is the point on
Earth’s surface directly
above the focus.
EARTHQUAKE WAVES
Seismographs record earthquake
waves
Seismograms show:
• Amplitude of seismic waves (how much
rock moves or vibrates)
• Distance to the epicenter
• Earthquake direction
EARTHQUAKE WAVES
3 types of seismic waves show up on seismogram
– P waves: shake Earth in same direction as
wave;
travel thru solid, liquid, gas
– S waves: shake Earth sideways to wave
direction;
travel thru solids only
– Surface waves (L waves): circular
movement of rock; travel on surface –
cause most damage!!
EARTHQUAKE WAVES
P waves move through solids & liquids
S waves move through solids only!!!
EARTHQUAKE WAVES
Body
P waves
S waves
waves
AKA
Moves
through
Movement
of rock
Primary (1st to arrive)
Secondary (2nd to arrive - larger)
Longitudinal, Compression
Transverse, Shear
all states of matter
(solid, liquid, gas)
back and forth movement of rock
• push/pull or compression/stretch
out
• Like slinky down stairs
Vibration is same as the direction of
travel
Can go through solids only
Move sideways
•
•
perpendicular to direction of
wave travel
Like snake
Surface or L Waves
▪ Seismic waves that move along Earth’s surface, not
▪
▪
▪
▪
through its interior.
Make the ground roll up and down or shake from side
to side.
Slowest moving seismic waves
Travel on top of Earth’s surface
Cause the largest ground movements and the most
damage as they bend and twist the surface
EARTHQUAKE MAGNITUDE
measures the size of seismic waves →
the energy released by the earthquake
Richter scale=measurement of energy released
based upon wave amplitude (size of vibration)
• <2 to ~10
• Amplitude of wave goes up
by 10 (Logarithmic scale, which
means each is # is 10x’s stronger)
What you need:
• Amplitude (size of vibration = wave height)
• Time between arrival of 1st P and 1st S waves
HOW TO READ SEISMOGRAMS
P & S (body waves) move through earth & arrive first
• P & S waves used to calculate magnitude of earthquake
• Amplitude = height of wave (how much the rock moves; size of
vibration)
Occurrence of Earthquakes
▪ About 80 percent of all earthquakes
occur in a belt around the edges of the
Pacific Ocean.
▪ In the United States, the best-known
fault in this belt is the San Andreas
Fault in California.
San Andreas Fault – This is a Transform
Boundary that runs from the Gulf of California
through the San Francisco area.
Kinds of Faults
The three main types of faults are
1) Normal faults,
2) Reverse faults, and
3) Strike-slip faults.
Normal Faults
Here the block of
rock above the fault
plane slides down
relative to the other
block. Stress that
pulls rocks apart
causes normal
faults. Example Great Rift Valley of
Africa.
Reverse Faults
Here the block of rock
above the fault plane
moves up relative to the
other block. Stress that
presses rocks together
causes reverse faults.
These faults can occur
near collision-zone
boundaries between
plates. Example Himalayan Mountains
have many earthquakes
along reverse faults.
Strike-Slip Faults
Here blocks of rock move
sideways on either side of
the fault plane. Stress that
pushes blocks of rock
horizontally causes
earthquakes along strikeslip faults. These faults can
occur where plates scrape
past each other. The San
Andreas Fault is a strikeslip fault.
Tsunamis
A special type of wave that can make
water rise more than the height of a 20story building. This wave, known as a
tsunami, is a water wave triggered by an
earthquake, volcanic eruption, or
landslide. Tsunamis are sometimes called
tidal waves.
Essential questions review
All students must be able to answer the following
questions.
● What are the different layers of Earth?
● Why are Earth’s layers arranged in this order?
● How does the inside of Earth affect the outer layer of
Earth (crust)?
● How and why is Earth constantly changing?
(In your answer include how crustal plates and ocean
basins are formed, move, and interact using earthquakes,
heat flow, and volcanoes to reflect forces within the Earth).