2. Earthquake = the shaking and
trembling that results from
movement of rock beneath
Earth’s surface
Focus = area beneath Earth’s
surface where rock under stress
breaks and causes an
earthquake
Epicenter = point on the
surface directly above the focus
3. A. Earthquakes produce vibrations called
Waves.
B. Waves carry energy.
C. Seismic waves are vibrations that travel
through Earth carrying energy released
during an earthquake.
4. D. Seismic waves carry energy from an
earthquake away from the focus, through
Earth’s interior and across the surface.
E. Three main categories of Waves:
Primary Waves (P waves)
Secondary Waves (S waves)
Surface Waves
5. The first waves to arrive are Primary waves.
› P waves compress and expand the ground.
After P waves come Secondary waves.
› S waves are seismic waves that vibrate from Side to
Side as well as up and down.
When P waves reach the surface, some of them
become Surface waves.
› Surface waves move more slowly than P or S waves
but they produce severe ground movements.
8. There are at least 3 different measures
for rating earthquakes.
Two methods for measurement:
› Mercalli Scale
› Richter Scale
Mercalli Scale = Rate earthquakes on the
level of damage at a certain place
10. Richter Scale = rating of an
earthquake’s magnitude
based on the size of the
earthquake’s seismic waves
› Magnitude is a number
geologists assign to an
earthquake based on the
earthquake’s size
› the seismic waves are
measured by a seismograph
11. Comparing Magnitudes
› An earthquake’s magnitude tells Scientists
how much energy was released by the
earthquake
› Earthquakes with a Magnitude of 6 cause?
Moderate damage
32 times the energy of a
Magnitude 5 Quake
12. Geologists use seismic waves to locate
an earthquake’s epicenter.
13. Recording
Station
Time Difference
in the arrival time
of P- wave and
S- wave
(seconds)
Distance of
epicenter from
the stations
Occidental
Mindoro
40
Samar 32
Zamboanga
del Norte
36
15. 1. Is earthquake predictable? Explain
your answer.
2. What is the minimum number of
seismic stations necessary to locate an
epicenter?
3. How can you determine the epicenter
of an earthquake using data from
seismic stations worldwide?
(COPY AND ANSWER THIS AFTER COPYING
NUMBER 5 ON PAGE 9)
16. 4. Where was the epicenter of this
earthquake located?
5. Your circle must not have
intersected precisely at one point.
Other than the error in your
measurement, what are the possible
reasons for this? (Be specific.)
Editor's Notes
#2:Intro to Earthquakes http://www.youtube.com/watch?v=JrBaiPN6AW8
#6:Refer to Textbook ….page 56 Math Skills
Answer Questions 1 – 4
X axis is Distance from Epicenter and Y axis is arrival time
2. 7.5 minutes
4 minutes
2000 = 3.5 minutes and 4000 = 4.5 minutes
