2.  Tectonic plates are massive, moving pieces
of Earth’s lithosphere
 Plates ride above circulating, heated rock
 Geographers study plate movements to
understand:
- how the earth is reshaped
 - how earthquakes and volcanoes are formed
 The largest plates are named after
continents: page 37

4.  Plates move in one of four ways: page 38-39
 Divergent- by spreading, or moving apart
 Subduction - diving under another plate
 Convergent- collision, or crashing together
 Transform- sliding past each other in a
shearing motion

5.  Movement of plates effects surface
of the earth
 Saudi Arabia–Egypt’s plates are
spreading apart, widening Red Sea
 India’s plate is crashing into Asian
continent, building up Himalayas

9.  Peru-Chile Trench

15.  Two plates meeting can cause folding,
cracking of rock
 -Platesmove very slowly
 - Causes rocks to become more flexible and fold
under pressure

17.  Faults occur when pressure causes rock to
fracture, or crack.
-Sometimes the rock is not flexible and will
crack due to plate movement
 The crack is called a fault
 Fault line is place where plates move past
each other

19.  As the plates move past each other at a
fault, the earth shakes or trembles
 This movement may become violent, called
an earthquake

20.  Seismograph
 -Special
device used to detect earthquakes
-Measures the size of the waves created by an
earthquake

21.  Earthquakes release energy in the form of
motion, causing:
- landslides
 - land displacement
 - fires (broken gas lines)
 - collapsed buildings
 Richter Scale — numeric scale showing relative
strength of earthquake
 -Uses info from seismographs to determine the strength of
an earthquake
 -Has no absolute upper limit
 -Major quake measures a 7 or more

23.  Location in the earth where an earthquake
begins is called the focus
 Epicenter — the point directly above focus
on the earth’s surface
- In most cases, the epicenter is the area that
receives the greatest damage
 Nearly 95% of earthquakes occur at tectonic
plate boundaries

25.  Tsunami, a giant ocean wave, begins at
epicenter of an earthquake:
- travels at up to 450 mph
 - waves of 50–100 ft. or higher
 May travel across wide stretches of the ocean
and do damage on distant shores

26.  On March 11, 2011 an 8.9
magnitude earthquake struck
Japan.
 The earthquake and
subsequent tsunami has
caused vast amounts of
damage and the death toll
continues to rise.
 Nearly 16,000 people died as
a result.

27.  On December 26th, 2004, an
earthquake caused by
subduction caused a series
of tsunamis along the
coasts of the Indian Ocean.
 Some waves were said to
be upwards of 98ft. high.
 Killing over 230,000
people, the 2004 tsunami
is the worst natural
disaster in history.

29.  Volcanoes occur
where there are
cracks in the
earth’s surface.
Material, such as
magma, pours out
of the vent.
 Most volcanoes
occur at tectonic
plate boundaries

30.  There are several
types of eruptions—
violent explosions
where lava, gases,
ash or dust are
expelled from the
vent in Earth’s crust
 Lava — magma that
has reached the
earth’s surface; may
create landform

33.  Ring of Fire —
zone around rim of
Pacific Ocean:
- meeting point of
eight tectonic
plates
 - vast majority of
the earth’s active
volcanoes located
here

34.  “Hot spots” are where
magma rises to surface
from mantle
 Hot springs, geysers
indicate high
temperatures in earth’s
crust
 Some volcanic action is
useful:
 - volcanic ash produces
fertile soil
- hot springs are tapped
for heat, energy