Transcript Investigating the Earth`s Formations

Volcanoes and Earthquakes
Eric Angat
Environmental Science
Essential Questions
How do I describe the
relationships between
plate boundaries,
volcanoes, and
earthquakes?
1. What is the theory of Plate tectonics?
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P. 455-459
Seafloor spreading explains why the
oldest part of the ocean floor is found
farthest from the mid-ocean ridge.
Alfred Wegener called the large
supercontinent that once existed as
Pangaea.
Scientists believe that tectonic
plates move because of the
convection current in the
mantle.
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2. How do the continents move?
The Earth's crust is divided into
large slabs of rock that drift and
collide together because of the
convection current in the
asthenosphere ( mantle ). These slabs
of rock
are the tectonic plates.
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San Andreas Fault, California
3. Why are earthquakes common in the California
and Alaska? Think!
4. Complete concept map.
Use the following words.
•P-waves
•S-waves
•back and forth
•Right angle
•rolling
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P-waves
back and forth
S-waves
Rolling motion
•Right angle
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5. How are buildings designed to
withstand earthquakes? p. 511
The process of making structures, such as buildings and bridges,
stronger against earthquakes is called
seismic retrofitting
P-waves are earthquake waves that
fastest and arrive at a location first.
travel the
(01:47)
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Energy released during an
earthquake creates seismic
waves.
Earthquakes usually
occur along tectonic
plate boundaries,
especially in the Pacific
Ring of Fire.
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6. What is a fault and how does it cause
an earthquake? Think!
Fault is a break on earth
crust where pressure builds
up. When this pressure is
released an earthquake
happens.
The sudden movement generates an earthquake at a
point called the focus. The energy from the
earthquake spreads out as seismic waves in all
directions. The epicenter of the earthquake is the
location where seismic waves reach the surface
directly above the focus.
Slab pull
in the Subduction zone
Seismic waves travel in all directions.
Tsunamis are mostly undetectable in
the deep oceans.
P. 490
7. Why does Earth’s
temperature drop when
volcanoes erupts?
Illustrate and
explain your
answer.
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Pyroclastic cloud
8. Draw and describe a Composite Volcano.
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The most dangerous volcanoes
are composite volcanoes. Why?
P. 482-483
9. Draw and Describe a Cinder Cone Volcano.
P. 482-483
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10. Draw and describe a Shield Volcano.
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P. 482-483
(02:05)
Mauna Kea (left) and Mauna Loa (right), both over 4000 m above sea level, are the world's
largest active volcanoes, rising nearly 9 km above the sea floor around the island of Hawaii.
This aerial view from the NW shows the contrasting morphologies of these two shield
volcanoes. In contrast to the smooth profile of Mauna Loa, Mauna Kea's early shield volcano
morphology is modified by the late-stage products of explosive eruptions.
Photo by Lee Siebert, 1987 (Smithsonian Institution).
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The Ring of Fire refers to the
volcanoes surrounding the Pacific
Ocean
Subduction zones occur all around the
Pacific Ocean basin. This entire region
is known as the Ring of Fire .
The Hawaiian Island
chains were formed by a
hot spot
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11. What are effects of a volcanic eruption?
Pyroclastic materials
Acid rain from sulfur
Tephra
Earthquake
488-490
LandslidesP.(mass
Lava
Lahar
movement)
Positive
Negative
The dramatic scenery created by
volcanic eruptions attracts tourists.
This brings income to an area.
Many lives can be lost as a result of a
volcanic eruption.
The lava and ash deposited during an
eruption breaks down to provide
valuable nutrients for the soil. This
creates very fertile soil which is good
for agriculture
If the ash and mud from a volcanic
eruption mix with rain water or melting
snow, fast moving mudflows are
created. These flows are called lahars.
The high level of heat and activity
inside the Earth, close to a volcano,
can provide opportunities for
generating geothermal energy.
Lava flows and lahars can destroy
settlements and clear areas of
woodland or agriculture.
Human and natural landscapes can
be destroyed and changed forever.
12. How do granite ( igneous) rocks form?
p. 117
(05:01)
oceanic-oceanic boundary
Island Arc
Ocean
Ocean
Subduction
When two oceanic crust collide subduction
happens and the melted crust rises to form a
volcanic arc.
Oceanic – oceanic convergent boundary
oceanic-continental boundary
oceanic plate
Subduction continental plate.
An oceanic plate is heavier than a continental
plate that is why it sinks under the
continental plate.
Oceanic – continental convergent boundary
ocean ridge or mid ocean
ridge
This is happening in the Atlantic ocean. The oceanic plate is
diverging ( moving apart) and the gap is filled by cooled lava
forming basalt. The Atlantic ocean is widening by about 2-3
cm. or 1 inch every year.
ocean ridge or mid ocean
ridge
oldest
youngest
oldest
The oldest sea floor is the one farthest from the ridge and
the youngest sea floor is the one nearest to the ridge.
continental-continental
boundary
When two continental crust converge. A mountain range is
formed. An example of this is the converging plates of
India and Asia, where Himalayas is still forming (Orogenymountain building).
Continental-continental convergent boundary
A transform boundary exists where one
of the Earth's plates slides past
another plate
Evidences that Earth's surface consists of
plates that are in continuous motion include
earthquakes, mountains, and
volcanoes.
The San Andreas fault is an example of
strike-slip fault.
The San Andreas fault is an example of
transforms or sliding boundary.
The San Andreas fault is an example of
shear stress
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Anatomy of the San Andreas Fault
Landform
San Andreas
Fault
Location
Type of
fault
strike
-slip
fault.
Type of
boundary
Type of
stress
transforms
or sliding
boundary
shear
stress
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