4. Do you know what this means?
S6E5. Students will investigate the
scientific view of how the earth’s
surface is formed.
c.Describe processes that change
rocks and the surface of the earth.
6. • Are the result of
“pulling” forces
• Have small
earthquakes
• Create many
normal faults
• Are usually on the
opposite side of
the plate from a
convergent
boundary
7. • Collision of two
plates
• Have all the large
earthquakes
• 90% of all
earthquakes
happen here
• Ocean-continent
collisions =
subduction
• Explosive volcanoes
• Reverse faults
8. • Are the result of
parallel and
opposite forces
• Have small to
medium
earthquakes
• Create strike-slip
faults
• Can cause
streams to turn
at right angles
9. Stress
Due mostly to plate
movements, the earth’s crust
is under a lot of stress. There
are 3 types, shown at the
right
o“A” occurs where plates pull
apart, divergent boundaries,
and is called tension
o“B” occurs where plates
converge, and is called
compression
o“C” occurs where plates move
past each other, at transform
fault boundaries and is called
shearing
10. Strain • Stress leads to strain on
the crust which bends it.
If it is warm, under the
ground, it can bend.
The features are called
folds.
• Upturned folds are
anticlines while
downturned folds are
synclines.
• Or the rock may break,
if it is brittle. This
anticline syncline
fold above and
a fault below
11. Different faults
Faults move in different
ways, depending on the
type of stress on them.
Remember “3” types
form.
1.Normal fault
2.Strike slip fault
3.Reverse fault 3
14. Plate Tectonic and Mountain
Formation
• The most common types of mountains:
1. Folded Mountains: from when rock layers are
squeezed together and pushed upward –Ural
Mountains (Russian)
2. Fault-Block Mountains: form when tension
causes land to drop down – Teton Range (USA)
3. Volcanic Mountains: molten material rises to
the Earth’s surface and erupts on the surface
- Mount Kilimanjaro (Africa)
15. Mountain Formation
Mountains can be a result of:
1.Continental Collisions (Himalayan
Mountains; Alps in Europe)
2.Volcanic Eruptions (Mount Kilimanjaro-
Africa; Parícutin-Mexico)
3.Hot Spots (Mauna Kea- Hawaiian Islands)
4.Subduction Zones (Andes Mountains)
5.Sea-floor Spreading (Mt. Oraefajokull
-Iceland: Mid-Atlantic Ridge)
17. • When continental crust pushes against continental
crust both sides of the convergent boundary have
the same properties.
• Neither side of the boundary wants to sink
beneath the other side, and as a result the two
plates push against each other and the crust
buckles and cracks, pushing up (and down into the
mantle), forming high mountain ranges.
• Examples:
1. The European Alps
2. Himalayan Mountains
21. Interesting plate collision
This picture shows a
place in Newfoundland
where a massive
collision actually
forced mantle rock on
top of the crust,
during the collision
that formed Pangaea
and the Appalachian
mountains. This looks
down the old plate
boundary.
24. Volcanic Mountains
Volcán de Parícutin
• A recent witnessed example of a volcano being born
was the spectacular event that began on February 20,
1943, when a farmer's cornfield in Mexico suddenly
began to erupt. By the second day, the cone had risen
to 100 feet (30.5 m.). By two weeks it was 450 feet
high (137 m.), and when the eruptions finally ceased in
1952 the cone had risen to 1,350 feet (411 m.).
25. Basic Earthquake Facts
• Mostly happen along/on plate boundaries
• Seismographs can record earthquakes
from all over the world
above 2.5-3 on magnitude
scale
• Earthquakes are a
release of energy
26. Earthquakes
• Earthquake – The shaking and
trembling that results from the
sudden movement of part of the
Earth’s crust
– Pebble in pond
– Scientists predict over 1,000,000
earthquakes happen each year
– Faulting is most common reason
for Earthquakes
• San Andreas Fault
– Fault Video
http://youtu.be/ZxPTLmg0ZCw
27. Fukushima’s Earthquake
• An earthquake shook Fukushima in 11th
March 2011. It caused a tsunami.
• As a result of the
earthquake and tsunami, there
was an explosion in nuclear reactors.
http://youtu.be/qtCLlNFUhWk
(stop at 3:10—coast before/after)
28. Tsunamis
• Also called tidal waves
• Large ocean waves caused by an
earthquake under the ocean.
• Ocean floor moves along a fault creating
a wave.
• Can also be caused by a landslide under
or above the water.
29. Tsunamis
• Remember this huge
wave is caused by an
earthquake on the floor of
the ocean
– They can travel at speeds
of 700 to 800 MPH
– They can reach Heights of
20 meters
• The height of a 6 Story
Building
• Tsunami Off of Thailand
• Trouble in Paradise
30. Seismic Waves
• Earthquake waves are
known as seismic waves
– Focus- The point beneath
the Earth’s surface where
rocks break and move
• The focus is the point of
origin for the earthquake
– Epicenter- Directly above
the focus on the Earth’s
surface
• Earthquake waves reach the
epicenter first
• Seismic Waves
31. Seismic Waves
• Primary waves-
– “P-waves”: Seismic
waves that travel the
fastest
• They arrive at a given
point before any other
type of wave
• They travel through
– Solids
– Liquids
– Gases
32. Seismic Waves
• Primary waves-
– They move through the
Earth differently
depending on the
material they are
traveling through
– As they move deeper
into the Earth, where it
is more dense, they
move faster
– They are push-pull
waves
33. Seismic Waves
• Secondary Waves
– S-Waves – Seismic waves that do not travel
through the Earth as fast as P-waves do
– S-waves arrive at a given point after P-waves do
– S-waves travel through solids but not liquids and
gases
34. Seismic Waves
• Surface Waves
❖L-waves: They are the slowest moving seismic waves
• They arrive at a given point after P and S waves
➢They start at the epicenter and move along the Earth’s
surface
➢Earth’s surface moves up and down like water waves do
➢They cause the most damage to the Earth because they
bend and twist the surface
35. Seismograph
• Seismograph – An
instrument that
detects and
measures seismic
waves
– Consists of
• A weight attached to a
spring or wire
• A pen attached to the
weight that records the
movement of the Earth
on a paper, that is
wound tightly around a
constantly moving drum
36. • Seismologists – Scientists who
study earthquakes
– PSP Seismograph
– They can determine the strength of
an earthquake by studying the
height of the waves
• They look at a Seismogram
• They match the seismogram to a chart
called the Richter Scale
– Invented in 1935
– The scale is from one to ten, with any
earthquake above 6 being very
destructive
Seismograph
38. Earthquakes may cause:
1. Destruction of homes
2. Destruction of infrastructure (roads, bridges)
3. Soil damage
4. Landslides
5. Tsunamis
These can also result
from earthquake
aftershocks
39.
40. Volcanoes
❖An opening in the earth that erupts gases, ash
and lava.
o Caused by plate movement along boundaries.
o Occur at both divergent and convergent plate
boundaries.
41. –
t
Volcanoes
• Formation
–Magma: Rock deep within
Earth
• High temperature
• High Pressure
• Liquid State
• Found in pockets called magma
chambers
Magma constantly moves and
works its way through cracks
oward the surface by melting the
solid rock
42. • Formation
– Lava – Magma that has reached
the Earth’s Surface
– The place where magma becomes
lava is called a Volcano
– The opening through which lava
erupts is called a vent
• Volcanoes can have more than one
vent
– Lava will poor from the sides of a
volcano as well as the top
Volcanoes
43. Volcanoes
• All volcanoes form from an expulsion of
materials from deep within the earth in the
form of enormous amounts of lava or
cinders which pile up on the earth's
surface, forming a mountain.
MAGMA
44. • All are not Alike
– Some are quiet
• Lava oozes from a vent
– Others are violent
• With lava and other material hurled
hundreds of feet in the air
• Gases and earth material mix to be seen
from miles away
– The opening through which lava
erupts is called a vent
• Volcanoes can have more than one vent
– Lava will poor from the sides of a
volcano as well as the top
– Eruption
Eruptions
45. Types of Volcanic Eruptions
Two factors
determine the type
of eruption:
❖Amount of water
vapor & other gases
in the magma
❖The chemical
composition of the
magma
46. Eruptions
• During eruptions many rock fragments are blown
into the air
– Smallest
– Medium
– Large
= volcanic dust
= volcanic ash
= volcanic bombs
• Small volcanic bombs the size of golf balls are called Cinders
47. • Lahar (mudflow): mixture of
ash, eroded land, and water
flowing down river valleys
49. Types of
Volcanoes
Different types of volcanic eruptions form different types of
volcanoes
1.Cinder Cones - made mostly of cinders and other rock
particles that have been blown into the air
– Form from explosive eruptions
– Cones are not high
– Narrow base & steep sides
2.Shield Volcanoes – composed of mostly quiet lava flows
– Gently sloping, domed shaped mountain forms
1.Composite Volcanoes – Built up of alternating layers of rock particles
and lava
– First is a violent eruption
– Then a quiet eruption
– After many alternating eruptions a cone shape is formed
50. Volcano Visuals
• Shield – volcanic cone made
up of layers of hardened
lava
• Cinder cone – volcanic cone
made up of rock particles,
dust and ash.
• Composite – volcanic cone
made up of alternating
layers of lava and rock
particles.
56. • Conduit: the path that magma
takes from the magma chamber
to the vent
57. • Fissure: a long fissure (crack)
from which lava flows
58.
59.
60. • Scientists study the
makeup of the lava that
spews from the volcanic
vents to gain knowledge
about the interior magma
• Types of Lava
– Dark-colored/ Water
– Light-colored/ little Water
– Chemical composition of
both
– Large amounts of gases
• Steam and carbon dioxide
Eruptions
61. 3 Types of Lava
1. Pahoehoe lava:
➢ Hot, thin, fast
flowing
➢ harden with a
relatively smooth
surface
➢ Often has a ropy or
wrinkled appearance
63. 3. Pillow Lava:
➢Lava suddenly
cooled by
water
➢shows sack-
like segments
(stuffed
pillows)
64. Ring of Fire
A chain of volcanoes located in the Pacific Ocean
65. Hot Spots
• A part of the mantle is REALLY hot and
magma is forced up to the surface
• Creates islands.
– (Example: Hawaiian Islands)
66. Magma that may originate in the
mantle or outer core will move
upward, breaking the surface and
forming a volcano, they are
independent of plate boundaries and a
chain of volcanoes may form as the
plate moves across a hot spot.
67. • Three Major Zones
– Nearly all the way around the edge of the
Pacific Ocean
• Called the Ring of Fire
– Near the Mediterranean Sea
• Called the Mediterranean Zone
– Third Extends through Iceland to the middle of
the Atlantic Ocean
• Mid-Atlantic Ridge – Long ridge of volcanoes
Zones
68. Volcano Activity Levels (Stages)
1. Active (awake): Has erupted within recent
time and can erupt again at any time.
Pre-eruption activities:
• Increase in earthquake activity under the cone
• increase in temperature of cone,
• melting of ice/snow in the crater
• swelling of the cone
• steam eruptions
• minor ash erupt
69. 2. Dormant (sleeping):
•No eruption within recent times, but
there is record of past eruptions
•Can become active and erupt again
after a “wake up” period
•Example: Mt. Rainier
70. 3. Extinct:
➢No eruption within recorded history
➢Not expected to ever erupt again
➢Example: Mount Mazama (Crater
Lake)
