• Mountain Building…11
• Earthquakes…12
• Volcanoes…13
Ch. 11 – Mountain Building
A. Stress
deformation - the bending, tilting,
and breaking of the earth’s crust
- isostatic adjustments and plate
movements cause stress on the
earth’s crust
- stress causes strain in the rocks,
which can cause bending, tilting, or
breaking
three types of stress:
1. compression - occurs when crustal rocks
are squeezed together
2. tension - force that pulls rocks apart
3. shearing - forces that pushes rocks in
opposite directions past each other
B. The Results of Stress
1. Folding
- when rock is permanently deformed by stress
without breaking
three types of folds:
a. anticline - upcurved folds in the layers
b. syncline - downcurved folds in the layers
c. monocline - gently dipping bends in the
layers
anticlines
synclines
monoclines
2. Faulting
- a break in the rock is called a fracture
- when there is movement along a fracture, it
is then called a fault
four types of faults:
a. Normal fault - hanging wall moves down
relative to footwall
- very steep fault plane
- occur along divergent
boundaries
b. Reverse fault - hanging wall moves up
relative to the footwall
- very steep fault plane
- occurs at convergent
boundaries
c. Thrust fault - like reverse fault except fault
plane is not steep at all
d. Strike-slip fault - rock on either
side slides past each
other horizontally
reverse fault
normal fault
strike-slip fault
Ch. 12 – Earthquakes
A. Elastic Rebound Theory
earthquake - vibrations of the earth’s crust
- as the rocks on each side of a fault move slowly,
the stress increases and they slowly deform until
suddenly they fracture and spring back to their
original shape (rebound)
- this rebound causes vibrations called seismic
waves, and a series of smaller tremors called
aftershocks
focus - area along the fault (under the surface)
where the earthquake begins
epicenter - point on surface directly
above the focus
- the focus can be very deep within
the earth, but most earthquakes
are shallow-focus earthquakes (070km beneath the surface)
B. Major Earthquake Zones
- there are three major zones along the earth where
earthquakes are the most common (these zones follow
plate boundaries - why?)
1. Pacific Ring of Fire
2. Mid-Atlantic Ridge
3. Eurasian-Melanesian Mountain Belt
Eurasian-Melanesian
mountain belt
Mid-Atlantic ridge
Pacific Ring of Fire
- there are other faults that do not lie within these
major zones, but they are usually not as big or as
active
•there is a fault in SE Missouri called the New
Madrid Fault which would cause major damage to
southern IL and southern IN if a major earthquake
occurred (it is supposed to within the next 50-100
years)
C. Recording Earthquakes
seismograph - instrument used to record earthquake
waves
- paper is shaken by an earthquake
underneath a stationary pen
D. Types of Seismic Waves
1. Primary Waves (P waves)
- move the fastest, so they are the first
waves to be recorded from an earthquake
- can travel through solids and liquids, so
they can travel through the entire earth
- do little damage (only slight vibration)
2. Secondary Waves (S waves)
- move slower than P waves, so they are the
second waves to be recorded from an e.q.
- can only travel through solid material, so
they cannot travel through the entire earth
- cause rocking back and forth
3. Surface Waves or Long Waves (L waves)
- slowest-moving waves, so they are last to
be recorded from an earthquake
- occur as P and S waves reach the earth’s
surface
- cause an up-and-down motion which is
violent and causes the most damage
E. Locating an Earthquake
- to find the epicenter of an e.q., use time difference b/t P
and S waves
- must use three different recording stations
to locate an e.q. in a technique called
triangulation
ex.)
epicenter
F. Earthquake Measurement
1. Richter Scale
- scale from 1 to 10 in which each whole
number is 32 times as large as the number
before it
ex.) a 3 earthquake is 32 times larger in
magnitude than a 2 earthquake
a 4 earthquake is 1024 times larger in
magnitude than a 2 earthquake
- earthquakes below 2.5 are called
microquakes and are not felt by anyone
- not used anymore by scientists (only useful for a
handful of earthquakes)
2. Moment Magnitude
- similar to Richter scale, but takes into account
more factors to actually calculate energy
(magnitude) of eq
3. Mercalli Scale
- expresses the intensity of the earthquake, or
the amount of damage an earthquake does
- uses Roman Numerals from I to XII, with
each numeral having a description of the
damage it would cause to structures, etc.
ex.) II = Felt by only a few persons at rest, especially on
upper floors of buildings; delicately suspended
objects may swing slightly
X = Some well-built wooden structures destroyed; most
masonry and frame structures destroyed with
foundations; ground badly cracked; rails bent;
landslides considerable from riverbanks and steep
slopes; shifted sand and mud; water splashed over
banks
E. Earthquake Damage
1. Destruction to Buildings and Property
- buildings not usually built to withstand swaying
or shaking
- tall buildings can fall on others nearby
- fires can occur because of broken gas lines
- loose soil or rock underneath a structure can
vibrate and become like a liquid
- landslides can be triggered by vibrations
- freeway destruction near Los Angeles, 1994
- Building
damage
from EQ in
Kobe,
Japan,
1995
- Building damage from
EQ in Washington, 2001
- Freeway destruction
in Kobe, Japan, 1995
- Homes destroyed in
western India, 2001
- Roads and land deformed in Japan, 2004
- EQ in Japan, 1999
- Rail damage from EQ in
Turkey
http://earthquake.usgs.gov/re
gional/states/events/
- Fence displaced by
EQ near San
Francisco, 1906
- magnitude 9.2 EQ in Anchorage, Alaska, 1964
http://alaska.org/videosphotos/videopop3.jsp?Alaska_Summer_AK_CH_Feature_1964_EarthquakeFLV100001.flv,Alask
a_Summer_AK_CH_Feature_1964_EarthquakeFLV300001.flv
2. Tsunamis
- major earthquakes that occur on the ocean
floor can trigger giant waves called tsunamis
- tsunamis seem to begin small because most of the
wave is underwater, but as the wave moves towards
shore, the wave (still the same height) sticks out of
the water more as it is pushed up by the upward
slope of the seafloor near the shore
tsunami
earthquake
tsunami
http://www.pbs.org/wgb
h/nova/tsunami/anatomy
.html
- tsunamis caused by the
Good Friday Earthquake
drove a 2x6 plank through
this 10-ply truck tire at
Whittier, Alaska
EQ video that caused the tsunami near Banda Aceh,
Indonesia
Tsunami video from Indonesia
Tsunami video from Indonesia
Tsunami video from Sri Lanka
Tsunami video from Banda Aceh, Indonesia
Shortterm
predictions
Longterm
predictions
F. Earthquake Warnings and Predictions
1. Use paleoseismology, or the study of past
earthquakes to predict when future ones will occur
2. Use seismic gaps to determine where the rock is
locked and has not been moving
3. Use precursors, or small tremors right before an
earthquake, to give a short-term warning
4. Use the slow down of other P waves to predict
whether an earthquake will occur
Ch. 13 – Volcanoes
A. Volcanism
volcanism – the movement of
magma toward or onto the
surface of the earth
B. Volcanic Features
C. Major Volcanic Zones
1. Subduction Zones
- convergent boundaries
- continental coasts or island arcs
ex.) Pacific Ring of Fire
2. Mid-Ocean Ridges
- divergent boundaries
- rifts along ocean floor (occasionally
through dry land)
ex.) Iceland (Mid-Atlantic Ridge)
3. Hot Spots
- volcanism outside of plate boundaries
- as plate moves, old volcanoes move
on and new ones form over hot spot
ex.) Hawaiian Islands
http://dsc.discovery.com/convergence/pompeii/videogallery/videogallery.html
D. Volcanic Eruptions
1. Kinds of lava
a. mafic (basaltic) lava
– dark colored when hardened, rich in
magnesium and iron, usually from oceanic
crust
dry
magma
- very little gas and water vapor
- quiet eruptions with more lava and very
little tephra
wet
magma
b. felsic (granitic) lava
– light colored when hardened, rich in
silica, usually from continental crust (more
gas and water vapor)
- more gas and water vapor (and, thus,
more pressure built up)
- violent eruptions with more tephra and
less lava
c. Lava textures
- thin, mafic lava usually hardens
slowly with a wrinkled surface 
pahoehoe
http://dsc.discovery.com/convergence/pompeii/videogallery/videogallery.html
- if lava cools quickly, it
forms large, jagged chunks
 aa
- if lava cools underwater, it
cools rapidly, usually in a
round shape  pillow lava
E. Volcanic Rock Fragments
1. tephra - rock fragments ejected from a
volcano
- also called pyroclastic material
a. ash - less than 2 mm
b. dust - less than 2.5 mm
c. lapilli - less than 64 mm
d. bombs - large, round clots of
lava that partially solidify in the air
e. blocks - very large solid rock
blasted out of the volcano
http://dsc.discovery.com/convergence/pompeii/videogallery/videogallery.html
F. Volcanic cones
1. Shield cones - broad, gently sloping
- formed from quiet lava
eruptions
2. Cinder cones - short, steep slopes
- formed from explosive tephra
eruptions (aka: pyroclastic
flows)
3. Composite cones - tall, varying slopes
- alternating kinds of eruptions
What kind of cone?
composite cone
cinder cone
shield cone
cinder cone
cinder cone
cinder cone
composite cone
shield cone
shield cone
cinder cone
composite cone
G. Predicting Volcanic Eruptions
1. small earthquakes before an eruption
2. bulging of the surface of the volcano
3. changes in composition of gases given
off by the volcano
4. volcano’s past behavior