1. Review of Concepts

2. Plate Tectonic

3. Oceanic – Continental Convergence
1. Collision!!!
2. Continental Crust is less dense so Oceanic crust sinks (subducts) into the asthenosphere.
Forms Trenches

4. Oceanic – Oceanic Boundary
1. Collision!!!
2. The more dense ocean plate (older) subducts into the asthenosphere.
3. Forms Volcanic Islands

5. Continental – Continental Boundary
1. Collision!!!
2. Neither plate subducts because they are both low in density.
3. Pushed upwards form mountain ranges

6. Causes of Plate Movement
1.Convection Current in Mantle
2. Different states and different temperature of mantle and cust

7. Faults

9. What is an Earthquake?
Earthquake – a vibration of the Earth produced by a rapid release of energy.
Most often caused by slippage along a TRANSFORM FAULT boundary.

10. Earthquake Basics!
When the fault “snaps”. . . Energy travels out from the focus in waves like ripples in water.
Waves travel in ALL directions
P waves, S waves, Surface waves

11. Earthquake Waves Two types – BODY waves and SURFACE waves
BODY WAVES – waves that travel through the Earth’s interior.
Two kinds: P-waves and S-waves.
P-waves (push-pull waves)
Move things forward and back
S-waves (shake waves)
Move things up and down

12. Earthquake Waves
Surface Waves – waves that travel along the Earth’s surface
Surface waves travel up and down AND side to side AT THE SAME TIME!
Surface waves are the MOST DESTRUCTIVE of all the seismic waves

13. In order from FASTEST to SLOWEST P-waves (PRIMARY – first)
Seismic Wave Speeds
In order from FASTEST to SLOWEST
P-waves (PRIMARY – first)
S-waves (SECONDARY – second)
Surface waves (last)
The difference in wave speeds give us the information to determine two important measurements:
1. How far away from the seismograph the earthquake is
2. Where the epicenter of the earthquake is

14. Seismogram
The paper print out from the seismograph
Shows the arrival times of P-waves, S-waves and Surface waves

15. Earthquake Distance from Seismograph
How to calculate distance
1. Read seismogram to determine the time interval between 1st P-wave and 1st S-wave

16. How to Use the Earthquake Travel Time Graph
TRAVEL TIME or DISTANCE from EPICENTER (Given one, find the other)
Sample Problem: A seismic station is 3000 kilometers from the epicenter of an earthquake. How long will it take P waves from this earthquake to reach the seismic station?
You must always ask yourself two questions:
1) What information do I have?
3000 kilometers from the epicenter
2) What information am I looking for? If you don’t know what you’re looking for
it’s very unlikely that you’ll find it!
How long (time)

17. We know the distance (3000km)
We’re trying to find the time it will
take P waves to travel this distance.
Find 3 (really 3000km) on the bottom
axis and, using a straight edge
(a ruler) draw a line up to meet the
P wave line.
Now, using the ruler, draw a line over
to the left axis and read the travel
time: 5 minutes and 40 seconds.
Notice that each small box is worth
20 seconds.
Now try the same problem in reverse:
It takes P waves 5 minutes and 40
seconds to travel from an epicenter
to a seismic station. How far is the
seismic station from the epicenter?

18. TAKE THE TIME TO BE CAREFUL AND ACCURATE!
We know the P wave travel time:
5 minutes and 40 seconds.
We are trying to find the distance
between the epicenter and the
seismic station.
Using a ruler, draw a line from the
time (5:40) to the P wave line.
Now draw a line straight down to
the bottom axis and read the
distance
3000 kilometers!
All of these problems are the same.
Given the time, find the distance.
Given the distance, find the time.
And it doesn’t matter whether you
are given P or S wave travel time
as long as you are careful to use
the correct line and, most important:
TAKE THE TIME TO BE CAREFUL AND ACCURATE!

19. Let’s take this one step further
Let’s take this one step further. A seismic station is 3000 km from the epicenter of an earthquake. If P waves from that quake arrive at the station at 4:25:40 PM (4 hours, 25 minutes and 40 seconds), at what time did the earthquake occur?
We do exactly the same thing we
did before, we find the travel time which is 5:40 (5 minutes, 40 sec.)
Now some math. If the waves arrived at 4:25:40 and they’ve been traveling for 5:40, when did they start out?
Subtract: 4:25:40
5:40
4:20:00
The quake occurred at 4:20:00 PM

20. OK, let’s try another type of problem involving both P and S waves
OK, let’s try another type of problem involving both P and S waves. Here’s
an example
It takes P waves 7:20 (7 minutes and 20 seconds) to travel from an earthquake
epicenter to a seismic station. How long will it take S waves from the same
earthquake to reach the seismic station?
What do we know?
We know P wave travel time is 7:20
What are we trying to find?
We want to find S wave travel time.
Do we have enough information to do the problem?
NO!
We have to divide the problem into 2 parts. First, we do just what we did in
the previous problem. We use the P wave travel time to find the distance
to the seismic station and then
We use the distance to the seismic station to find how long it took S waves
to travel that same distance.
Let’s see how it’s done

21. And now for something completely different.......................
We know P wave travel time is 7:20
so, using a ruler, draw a line from
7:20 over to the P wave line.
Now draw a line straight down to find
the distance from the epicenter
The distance is 4200 km. Notice that
each small box on the bottom axis is
200 km.
Now we can get on with the second
half of the problem. If the seismic
station is 4200 km from the quake
epicenter, how long (time) did it take
the S waves to travel that same
distance?
Draw a line from 4200 km straight up
to the S wave line.
Now draw a line over to the vertical
axis and read the time
13 minutes exactly (13:00)
And now for something completely different

22. Another type of question involves the
“difference in travel time between P
waves and S waves”.
Whenever you are given the difference
in arrival times OR you are given both
times so that you can subtract and find
the difference, you should immediately
realize that you will be dealing with the
shaded area (yellow) between the two
lines.
Here’s a sample problem:
P waves arrive at a seismic station
4:30 (4 minutes, 30 seconds) before
the arrival of S waves from the same
earthquake. How far from the epicenter
is the seismic station?

23. Here’s what you know: P & S waves
arrive at a seismic station 4 minutes and
30 seconds (4:30) apart. You are asked
to find the distance to the epicenter.
Here’s how:
1) Take a sheet of paper and line up
the left edge with the vertical axis
(time). Be sure that most of the paper
is hanging down below the graph. This
is important.
2) Make a small, thin, and accurate mark
on the paper at 0 time. Make another
small, thin, and accurate, mark at 4:30
(4 minutes, 30 seconds).
Your 2 marks are now 4:30 apart!

24. Now slide your paper to the right
until one of your marks is exactly
on the S wave line and the other
is exactly on the P wave line. It is
very important to be sure your
paper is straight (vertical).
Now look to see where the bottom
of your paper crosses the lower
(epicenter distance) axis. In this
case it crosses at exactly 3000 km
which is the answer.
When P & S waves arrive 4 minutes
and 30 seconds apart it means that
the seismic station is exactly 3000
km from the epicenter of the quake.
Of course we can do the same
problem in reverse!

25. A seismic station is 3000 km from
the epicenter of an earthquake.
How long after P waves arrive will
S waves from the same earthquake
arrive at the station?
This time place your paper on the
3000 km mark taking care to keep
the paper straight and to cover
both the P and S wave lines.
Make small, thin, and accurate
marks where your paper crosses
the P line and the S line.
Then

26. Slide your paper to the left so that your
lower mark is on time 0.
Now just read the time indicated by your
top most mark: 4:30 (4 minutes and
30 seconds) which is the answer.
This kind of question may also be
phrased this way:
“P waves arrive at a seismic station at
12:32:00. S waves from the same
earthquake arrive at 12:36:30. How far
from the epicenter is the seismic station?
All you need to do is subtract in order
to get the difference in arrival times.
12:36:30
- 12:32:00
00:04: hours, 4 minutes, and
30 seconds.
Just remember, if you’re given 2 times, just subtract
to get the difference.

27. One last kind of problem to become familiar with
One last kind of problem to become familiar with. Sometimes, instead of giving you
the difference in arrival times, you will be given a seismogram (a record made by a
seismograph) instead.
Using this seismogram
find when the P waves
and the S waves arrive.
Do this by carefully
making a mark at the
P wave and S wave
arrival times.
Now count the number of
minutes between the
arrival of P and S waves at
the station.
From this point on it’s just like the previous problem: If the difference in arrival times
between P and S waves is 6 minutes, how far is the seismic station from the
epicenter of the earthquake?

28. Using the seismogram (on the previous
page) you determined that P & S waves
arrived at a seismic station 6 minutes
apart.
Place your paper along the vertical axis
(time) and make small and accurate
marks at time 0 and time 6. Remember
to keep most of the paper hanging down
below the graph.

29. Now slide your paper until one
mark is on the S wave line and the
other is on the P wave line. Be
absolutely sure that your paper
is straight (vertical).
Read the distance at the point
where the edge of the paper
crosses the bottom (distance)
axis.
Remember that each small box is
200 km. The answer is
4400 km!
That all there is to it. But doing
this once or twice won’t help. The
ONLY way to get good at anything
is to practice, practice and then
practice some more!

30. One last type of problem: Find the
‘time of origin of the earthquake’.
In other words, use the information
given to find out when the quake
occurred.
Here’s a sample problem: A seismic
station is 4000km from the epicenter
of an earthquake. P waves arrive
at the station at 2:48:00 PM. At what
time did the earthquake occur?
First, use the distance to find the P wave travel time.
OK, the P waves took 7 minutes to
travel the 4000km distance.
If they arrived at 2:48:00 and the
trip took 7 minutes, they must have
started out 7 minutes before 2:48 PM
So subtract. 2:48:00
:00
Origin time: 2:41:00 PM

31. Let’s try another one: P waves arrive
at a seismic station at 4:22:10 AM.
S waves from the same earthquake
arrive at 4:28:50 AM. What is the time
of origin of the earthquake?
First subtract to get the difference in
arrival times:
4:28:50
- 4:22:10
difference = :40 (6 min, 40 sec)
Now, as we did before, get a piece
of paper and carefully and
accurately make marks at time 0
and time 6:40

32. Slide the paper until one mark
is on the P wave line and the
other is on the S wave line.
Now read the distance from
the epicenter on the bottom:
4000 km.
Now that we know the distance
to the epicenter we can easily
tell how long it took P waves
to travel that distance.
P waves took 7 minutes to
travel the 4000 km and since
they arrived at 4:22:10 we
can subtract to find out when
they started.
4:22:10
:00
Origin time: 4:15:10

33. Never give up. Never let yourself sit there doing nothing!
Best advice:
Many students read a question and immediately realize that they do
not know what to do. They feel they are completely lost. In that case
there’s one important thing to remember:
DO SOMETHING! Just don’t sit there! Do something with the information
you have. For instance, if the question mentions P waves and gives a
distance, use that to find a travel time.
If the question gives a travel time for S waves use that to find a
distance to the epicenter.
Now you have a little more information than you had before. Re-read
the question. Be sure you know what you’re looking for and see if
you now have enough information to get the answer.
Never give up. Never let yourself sit there doing nothing!

34. Richter Scale
A scale that measures the magnitude of the largest wave recorded on the seismogram.
The wave amplitude increases by 10 for every 1 magnitude increase on the scale.
A Magnitude 3 has waves 10 times bigger than a Magnitude 2.

37. Other Types of Damage Tsunami – seismic sea waves
~often called ‘Tidal Waves” but they are NOT caused by the tidal effects of the moon or sun
~caused by underwater earthquakes
As waves near the shore, the water slows down and piles up on itself – waves reach heights of 30 meters and can go as fast as 50km/hr

38. 12/26/2004 - Tsunami hit Sumatra because of the 3rd most powerful Earthquake recorded since 1900.

39. Another Video of Japan - BBC link
Japan’s Tsunami after the 4th Most Powerful Earthquake on Friday, March 11th
Watch Video
Another Video of Japan - BBC link

40. Fire
Fire starts when gas or electrical lines are broken during an earthquake
~harder to put out because water lines are often also broken during an earthquake

41. Landslides The sinking of ground triggered by earthquake vibrations
Can cause foundations of buildings or even ENTIRE buildings to collapse
Can rupture gas, water or sewer lines

42. Historical Quakes Year Place Deaths Magnitude Other 1886
Charleston, SC 60
Greatest quake in Eastern US
1906
San Francisco
1500
7.8
Major damage
1923
Tokyo, Japan
143,000
7.9
Total destruction
1960
Southern Chile
5700
9.6
Largest quake recorded
1964
Alaska
131
9.2
Largest North American quake
1971
San Fernando, CA 65
6.5
Damage over $1 Billion
1989
Loma Prieta, CA 62
6.9
Over $6 Billion in damage
1994
Northridge, CA 57
6.7
Over $40Billion in damage
2001
Bhuj, India
20,000
Left 1 million homeless