Instructions:
I’ve attached a PDF of an assignment, that ideally, you can print out to fill out, otherwise you can do it on the computer by editing the PDF, but it may be harder than just working on the hard copy.
All you need to to do is take photos of each page you fill out and combine them into a file, then upload the album to Canvas by the due date.
P.S.:There
is also a video Instructions for this assignment that might help you on it, but I can’t upload on this post, so if you need i’ll find other way to send you.
Name: ___________________________________________
Date: __________________________ Period: ___________
Plate Tectonics
The Physical Setting: Earth Science
Lab Activity: Locating Epicenters
INTRODUCTION: !
Geologists who study earthquakes are called seismologists. If you were a seismologist, you would receive earthquake data from all across the country. Within minutes, seismologists would record the
times of arrival of the P waves and S waves. From the seismic wave data collected, they can than use
this data to zero in on the exact location of the earthquake’s epicenter.
OBJECTIVE: !
You will learn how to interpret a seismogram and use the data from three different seismograms to locate the epicenter of an earthquake.
VOCABULARY: !
Fault –
Epicenter !
!
!
Focus – !
!
!
!
Focal Depth –
P-wave –
S-wave –
Earth Science – “1
Lab Activity: Locating Epicenters
!
PROCEDURE A: !
Use the three seismograms from “Seismograms A” to calculate the following for each city and fill it into
the chart below:
1. The arrival time for the P and S wave.
2. The difference in the arrival time between P and S-waves.
3. The distance (in km) of the epicenter from each city.
4. Locate the epicenter on “Map A” by constructing a circle whose radius is equal to the distance
from the city to the epicenter for all three cities.
5. Where all three circles meet, draw an arrow and label it “epicenter”.
Station
Arrival Time
P-wave
S-wave
k
w
Ne
r
Yo
n
to
us
Ho
i
iam
M
Earth Science – “2
Difference in
Arrival Time
Distance to the
Epicenter
w
Se
av
w
av
e
00
3:
:2
12
00
2:
:2
12
00
1:
:2
12
00
0:
:2
12
Pe
av
w
e
av
w
S-
00
3:
:2
12
00
2:
:2
12
00
1:
:2
12
00
0:
:2
00
9:
:1
12
00
8:
:1
12
00
7:
:1
12
00
6:
:1
12
00
5:
:1
12
00
3:
:2
12
00
2:
:2
12
00
1:
:2
12
00
0:
:2
12
00
9:
:1
12
00
8:
:1
12
00
7:
:1
12
00
6:
:1
12
00
5:
:1
12
Earth Science – “3
12
00
9:
:1
12
00
8:
:1
12
00
7:
:1
12
00
6:
:1
12
00
5:
:1
12
P-
e
w
av
P-
e
w
av
S-
Lab Activity: Locating Epicenters
Seismograms A
New York
Houston
Miami
Seattle
San Francisco
Salt Lake City
0
0
200
600
800
Chicago
1000
1200
Savannah
1400 mi
800 1000 1200 1400 1600 1800 2000 km
Map A
400
200 400 600
Denver
Houston
New York
Miami
Earth Science – “4
Lab Activity: Locating Epicenters
PROCEDURE B: !
Use the three seismograms from “Seismograms B” to calculate the following for each city and fill it into
the chart below:
1. The arrival time for the P and S wave.
2. The difference in the arrival time between P and S-waves.
3. The distance (in km) of the epicenter from each city.
4. Locate the epicenter on “Map B” by constructing a circle whose radius is equal to the distance
from the city to the epicenter for all three cities.
5. Where all three circles meet, draw an arrow and label it “epicenter”.
Station
Arrival Time
P-wave
Difference in
S-wave
rk
w
Yo
Ne
n
to
s
ou
H
i
iam
M
Earth Science – “5
Arrival Time
Distance to the
Epicenter
e
av
w
e
av
w
S-
0
:0
46
3:
0
:0
45
3:
0
:0
44
3:
0
:0
43
3:
Pe
av
w
e
av
w
S-
0
:0
46
3:
0
:0
45
3:
0
:0
44
3:
0
:0
43
0
:0
42
3:
0
:0
41
3:
0
:0
40
3:
0
:0
39
3:
0
:0
38
3:
46
3:
45
3:
44
3:
43
3:
42
3:
41
3:
40
3:
39
3:
0
:0
0
:0
0
:0
0
:0
0
:0
0
:0
0
:0
0
:0
0
:0
38
3:
Earth Science – “6
3:
0
:0
42
3:
0
:0
41
3:
0
:0
40
3:
0
:0
39
3:
0
:0
38
3:
P-
e
w
av
P-
e
w
av
S-
Lab Activity: Locating Epicenters
Seismograms B
Houston
Miami
New York
Seattle
San Francisco
Salt Lake City
0
0
200
600
800
Chicago
1000
1200
Savannah
1400 mi
800 1000 1200 1400 1600 1800 2000 km
Map B
400
200 400 600
Denver
Houston
New York
Miami
Earth Science – “7
Lab Activity: Locating Epicenters
DISCUSSION QUESTIONS: !
1. What is the approximate location of the epicenter for the seismograms A?
2. What is the approximate location of the epicenter for the seismograms B?
3. Why is three the minimum number of stations necessary to locate an epicenter?
4. Why does the time between the arrival of the P-wave and S-wave become greater and greater as
you get farther away from the epicenter?
On the following map, you will need to estimate the time differences between the S and P waves that reveal
the appropriate distance to use. Try your best to estimate!
Earth Science – “8