More Earth Science Notes
Landforms
Mountains
•A mass of rock rising
meters above the surrounding land
•Relief vs. Elevation?
Types of Mountains
Fold Mountain
•Usually made mostly of
rock folded by compression forces
•These are the
most
and
of all mountains
Label:
Examples of Fold Mountains
•Appalachian Mountains
•
Mountains
•
•
Mountains
Fault-Block Mountain
•Fault Block Mountain Ranges are cause by a
series of
Examples of Fault block Mountain ranges
•
Mountains, CA
•
, WY
Label:
•Wasatch Mountains,
When the Earth SHAKES: Earthquakes
What causes earthquakes?
•Volcanic eruptions can cause earthquakes but most
earthquakes are caused
by
Label:
•These are often
called
earthquakes
Theory VS. Law
•A THEORY is a logical idea that has not been
directly but it can often be
proved
•It is a working set of rules that define a body of
•A LAW is observable and can be proven- to a point. However,
100% sure in a Universe as vast as ours
is
Elastic Rebound Theory
•The
Theory was first proposed by
American geologist Harry
after the 1906 San Francisco Earthquake
•The sudden release of progressively stored strain in rocks,
resulting in
along a fault
•After the stress becomes too great, the rock layers break,
back and
forth until eventually coming to a rest
•As the rock layers are shaking back and forth they send out waves of vibration called Seismic Waves
•“Seismic” always has to do with earthquake activity
Seismic Waves are waves of vibration sent out in all directions from the FOCUS
•Focus
The point
where the rock layers break and move
•Epicenter
The point on the surface,
It’s where the greatest
.
usually occurs
Fault
Measuring Earthquakes
26 April 1900 – 30 September 1985
Seismograph
•A machine that measures earthquake (
) waves
Early Seismograph
•Operates on the principle behind
Seismogram
•The
information of earthquake waves
Label:
The Richter Scale is based on MAGNITUDE
Each # is TEN TIMES larger than the # before it…
Pennies as an example:
Mag. 1 =
penny
Mag. 2 =
pennies
Mag 3 =
pennies
Mag. 4 =
pennies
Mag. 5 =
pennies
Mag. 6 =
pennies
Mag. 7 =
pennies
Mag. 8 =
pennies
Mag. 9 =
pennies
Mag. 10 =
pennies (that’s $10 million in pennies!!)
Richter Magnitudes
Earthquake Effects
Less than 3.5
Generally
3.5-5.4
Often felt,
Under 6.0
to buildings
6.1-6.9
Destructive to about
7.0-7.9
Major earthquake. Can cause
8 or greater
from epicenter
. Serious damage for hundreds of km
Anatomy of a basic wave
•
– the highest point on a wave (A, F)
•
– the lowest point on a wave (D, I)
•
– the distance between the midpoint & crest or trough
•
– distance between any two successive points on a wave
•
- # of vibrations/ second (Hertz)
Types of Seismic Waves
•Body Waves are waves that travel through the
•Surface waves only travel along the
Body Waves
Primary Waves AKA
•Type of Longitudinal Wave
•Causes
motion
•Follows the same direction as the energy transfer
•Type of COMPRESSIONAL wave (
•Will travel through
)
,
or
•Travels at:
•7.8 – 8.5 kps in
•7.2 kps in
crust
•3.5 kps in
crust
Secondary Wave AKA
•Particle motion is perpendicular to direction
of energy transfer
•Transverse or Shear Wave
•Will travel only through solids
•Travels 4 – 5 kps
Surface Waves
•
main types of surface waves:
•Love Wave
•Rayleigh Wave
•Recent evidence shows that L-Waves
(gradually disappear) more
slowly in older rock (eastern US) and more
in younger rock (western US)
Love Waves
• Love Waves travel less than
kps
• Move side-to-side; like a
• Cause the
Seismic Waves
with the P-Wave, S-Wave and L-Wave:
Triangulation
Refraction
•Refraction of
Zone between about
within the Earth
degrees &
degrees is the Shadow Zone:
Focus
105 degrees
145 degrees