Friday, March 23nd
• 1 Attendance
• 2 Go over
Review Sheet
• Test
• Pass Back
papers
Da’ Lab
• When did the P-wave hit?
• When did the S-Wave hit?
• Subtract to get the difference.
• Use the chart to find the epicenter distance
• Mark the edge of the paper with the time
difference
• Move paper to find the place where the two lines
are that far apart.
• Look down to see the epicenter distance
• Use the safety compass to draw the circle with the correct distance around the city.
Earthquakes
The sudden shaking of the ground.
I. Earthquakes



Are sudden trembling or
movement of the ground
There are over 1 Million
Per year (1 per second)
A major cause of
earthquakes is faulting
Fault
I. Earthquakes




Faulting – sudden
movement of rock along
planes of weakness in the
earth’s crust
Faults - planes of weakness
in the Earth’s crust.
Rock is stressed to the
breaking point and the two
halves have an elastic
rebound.
Great masses of rock
suddenly scrape past one
another.
Epicenter
Focus
I. Earthquakes


Focus - the point where
the rock breaks.
Epicenter - the point on
the Earth’s surface
directly above the focus.

Analysis of seismic
waves allows the
determination of the
location of epicenters.
Seismograph
Seismogram
II. Earthquake Waves


When faulting occurs,
vibrations called seismic
waves spread out in all
directions from the focus.
Seismograph - a device
that detects measures,
and records the motions
of the earth associated
with seismic waves.
II. Earthquake Waves


Seismogram - the
line that was
recorded on paper by
a seismograph
Magnitude - the total
energy released by
an earthquake
Richter Scale
Mercalli Scale
P-Waves
•
•
•
•
Primary / Compressional
First to arrive
Fastest
Can travel through Feverything:
• solids, liquids and air
S-Waves
•
•
•
•
Secondary Waves
Shear Waves
Second to arrive
Travels only through
• solids
Name
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Earthquake –
Faulting –
FaultFocus –
Epicenter –
SeismicSeismograph Seismogram Magnitude Richter Scale Mercalli Scale P-wave (primary) S-wave (secondary) -
Earthquake Vocabulary
Questions