San Francisco Earthquake of 1989 San Francisco Earthquake of
1989
Slide 3
Most earthquakes take place near the edges of tectonic plates
(most active earthquakes occur along the plates surrounding the
Pacific Ocean) What else is The Ring of Fire known for?
Slide 4
As tectonic plates push, pull or scrape against each other,
stress builds up along faults until the rocks finally move A fault
is a break in the Earths crust where plates slide, push or pull
against each other
Slide 5
Deformation is the change in the shape of rock in response to
stress. Rock can deform in 2 ways: - plastic - elastic
Slide 6
Stress causes the crust on one side of a fault bend like clay
THIS DOES NOT LEAD to EARTHQUAKES!!!!
Slide 7
Rock can only stretch so far before it will break Like a rubber
band, when it breaks, energy is released and the broken pieces
return to their unstretched shape causing energy to spread through
the earth in waves. THIS DOES LEAD to EARTHQUAKES!!!!
Slide 8
No. Depending on the type of plate boundary, earthquakes can be
strong or weak. Plate MotionEarthquake Characteristics
TransformModerate, shallow ConvergentStrong, deep DivergentWeak,
shallow ***Copy this chart in your notebook!***
Slide 9
Not all earthquakes are the same. The type of earthquake that
occurs depends on the type of plate motion and fault type there is!
***Write down the part in red***
Slide 10
If two plates have a transform motion, they will probably have
a strike-slip fault between them A strike-slip fault is when two
blocks of crust slide past each other horizontally These types of
earthquakes are moderate and shallow ***Write the definition of
strike slip in your glossary***
Slide 11
If two plates have a convergent motion, they will probably have
a reverse fault between them. A reverse fault happens when two
blocks of crust are pushed up against each other and they slide
vertically. These types of earthquakes are usually strong and deep.
***Write the definition of in your glossary***
Slide 12
If two plates have a divergent motion, they will probably have
a normal fault between them A normal fault occurs when two blocks
of crust are pulled away from each other and slide vertically This
type of earthquake is usually weak and shallow ***Write the
definition of in your glossary***
Slide 13
Earth on the Move Earth on the Move
Slide 14
All earthquakes release energy called seismic waves Scientists
measure seismic waves to determine the scale (how big or small) an
earthquake is Most people use the Richter scale to measure
earthquake seismic waves
Slide 15
http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM the
pendulum remains fixed as the ground moves beneath it
This is a seismograph It is an instrument located at or near
the surface of the Earth that records seismic waves
Slide 18
The Richter Scale MagnitudeEstimated Effects 2Can only be
detected by a seismograph 3Can be felt at the epicenter* 4Felt by
most in the area 5Causes damage at the epicenter 6Causes widespread
damage 7Causes great, widespread damage * Right where the
earthquake begins
Slide 19
Slide 20
A type of seismic wave that compresses and expands the ground.
Primary waves are longitudinal waves. They can travel through
liquids. The first wave to arrive at an earthquake. P comes before
S in the alphabet.
http://daphne.meccahosting.com/~a0000e89/insideearth2.htm ***Write
the definition in your glossary***
Slide 21
A type of seismic wave that moves the ground up and down or
side to side. These are transverse waves. They cannot go through
liquids. They are the second wave people feel. They are sometimes
called the aftershock.
http://daphne.meccahosting.com/~a0000e89/insideearth2.htm ***Write
the definition in your glossary***
Slide 22
Slide 23
Move along the Earths surface Produces motion in the upper
crust Motion can be up and down Motion can be around Motion can be
back and forth Travel more slowly than S and P waves More
destructive ***Write the definition in your glossary***
Slide 24
Scientists calculate the difference between arrival times of
the P waves and S waves The further away an earthquake is, the
greater the time between the arrival of the P waves and the S
waves
