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To Find The Epicenter of an Earthquake
Using the Difference in Time Between the P and the S Wave
Follow the Rainbow!
NSF Funded CUNY GK-12 Science NOW Project Copyright David Stolarz, January 22, 2010
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km 00:10:20 08:11:40
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
The Completed Process
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A
B
C
Fill out the chart below using the three seismograms and the chart on Page 11 of the Earth Science Reference Tables.
Start Simple – Draw a Line Down From the P-Wave to the Time Scale
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A
B
C
Fill out the chart below using the three seismograms and the chart on Page 11 of the Earth Science Reference Tables.
Judge what time the P-wave starts
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A
B
C
Fill out the chart below using the three seismograms and the chart on Page 11 of the Earth Science Reference Tables.
08:16 17 18 19
A Quarter after 8 O’Clock! And No Seconds!
A zoom-in shows P-wave starting at approximately 08:16:00
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00
B
C
Fill out the chart below using the three seismograms and the chart on Page 11 of the Earth Science Reference Tables.
Put that value in the appropriate box
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00
B
C
Fill out the chart below using the three seismograms and the chart on Page 11 of the Earth Science Reference Tables.
Repeat the same process for the S-wave.
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00
B
C
Fill out the chart below using the three seismograms and the chart on Page 11 of the Earth Science Reference Tables.
08:21:00 (S-Wave Time)-08:16:00 (P-Wave Time)
Calculate the interval between the two wave arrivals at the seisomgraph
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00
B
C
Fill out the chart below using the three seismograms and the chart on Page 11 of the Earth Science Reference Tables.
08:21:00 (S-Wave Time)-08:16:00 (P-Wave Time)00:05:00 (Time Difference)( 0 Hours, 5 Minutes, 0 Seconds )
Enter that time in the appropriate box
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00
B
C
Go to page 11 of your Earth Science Reference Tables for the chart shown above
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00
B
C
Use the P-S Wave time interval to figure out the distance to the epicenter
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00
B
C
Scrap Paper
Place Marks at P-S Wave Interval Time and at 0.
Create a reference measurement using scrap paper and the P-S Wave value
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00
B
C
Scrap Paper
Scrap Paper
Slide paper up and over until thereference marksLine up with the P and S Lines.
Find the proper place where the reference marks match the P and S Lines.
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00
B
C
Scrap Paper
Lightly, make a reference mark in pencil on the reference table at this place on the P line.
For convenience, make a light pencil mark on the P line for use in the next step
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00
B
C
Look straight down from the P line pencil mark and judge the epicenter distance.
.2 . 4 .6 .8
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km
B
C
Lightly, make reference marks in pencil On the reference table at these two places .
Enter that value for the epicenter distance with proper units.
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km
B
C
Look across at the y-axis to Judge the time value
00:06:40
00:06:20
Trav
el T
ime
(min
ute
s)
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20
B
C
Enter that value for the epicenter distance with proper units.
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20
B
C
ERASE YOUR MARK!
Erase your pencil mark on the P-wave to keep your reference table clean
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20
B
C
08:16:00 (P Arrival Time)00:06:20 (P Travel Time)
Calculate what time the earthquake happened using the Arrival and travel times
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20
B
C
08:16:00 (P Arrival Time)- 00:06:20 (P Travel Time)MINUS!
Obviously, the earthquake happened earlier than when its was felt miles away
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20
B
C
08:15:60 (1 min. is 60 sec)08:16:00 (P Arrival Time)
- 00:06:20 (P Travel Time)
Convert hours to minutes or minutes to seconds when necessary
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B
C
08:15:60 (1 min. is 60 sec)08:16:00 (P Arrival Time)
- 00:06:20 (P Travel Time)08:09:40 (Time at Origin)
Put the calculated time of earthquake in the proper box
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Anything complex is easier when broken into smaller steps
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00
C
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Judge what time the P-wave starts and enter it in the box
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00
C
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Repeat the same process for the S-wave.
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00
C
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Use the P-S Wave time interval to set reference marks for the sliding step
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00
C
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Create a reference measurement using scrap paper and the P-S Wave value
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00
C
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Find the proper place where the reference marks match the P and S Lines.
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km
C
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Look straight down from the P line pencil mark and judge the epicenter distance.
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20
C
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Look across at the y-axis to Judge the time value
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Put the calculated time of earthquake in the proper box
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Anything complex is easier when broken into smaller steps
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km 00:10:20 08:11:40
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Follow the same overall process for Station C
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Judge what time the P-wave starts and enter it in the box
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Repeat the same process for the S-wave.
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Use the P-S Wave time interval and the y axis of the reference table
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Create a reference measurement using scrap paper and the P-S Wave time value
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Find the proper place where the reference marks match the P and S Lines.
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Enter that value for the epicenter distance with proper units.
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km 00:10:20
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Calculate what time the earthquake happened using the Arrival and travel times
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km 00:10:20 08:11:40
Usin
g Scrap P
aper
Finding the Epicenter of an Earthquake Using the Difference in
Time Between the P and the S Wave
Calculate and place the time of earthquake in the proper box
$Z
$Z
$Z
A
C
B
0 5000 km
NSF Funded CUNY GK-12 Science NOW Project
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
3600 km
All three arcs must pass through the earthquake epicenter, in this case, the San Andreas fault in California, USA.
Using scrap paper.
Use the Station info to locate the epicenter of the earthquake on a map
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km 00:10:20 08:11:40
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
$Z
$Z
$Z
A
C
B
0 5000 km
On the Station Map, Find Station A
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km 00:10:20 08:11:40
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
$Z
$Z
$Z
A
C
B
0 5000 km
Find Station B
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km 00:10:20 08:11:40
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
$Z
$Z
$Z
A
C
B
0 5000 km
Find Station C
$Z
$Z
$Z
A
C
B
0 5000 km
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km 00:10:20 08:11:40
Distance to the Epicenter
3.6 x103 km
5.0 x103 km
7.6 x103 km
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
Station
A
B
C
Use the Distance to Epicenter for each station
NSF Funded CUNY GK-12 Science NOW Project
StationArrival Time of
P-WaveArrival Time of
the S-WaveP-S Wave Interval
Distance to the Epicenter
P-Wave Travel Time
Origin Time of Earthquake
A 08:16:00 08:21:00 00:05:00 3.6 x103 km 00:06:20 08:09:40
B 08:19:00 08:26:00 00:07:00 5.0 x103 km 00:08:20 08:10:40
C 08:21:00 08:30:00 00:09:00 7.6 x103 km 00:10:20 08:11:40
Distance to the Epicenter
3.6 x103 km
5.0 x103 km
7.6 x103 km
Distance to the Epicenter
3,600 km
5,000 km
7,600 km
or
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
Station
A
B
C
$Z
$Z
$Z
A
C
B
0 5000 km
Convert scientific notation for the distance to the epicenter for each station
NSF Funded CUNY GK-12 Science NOW Project
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
$Z
$Z
$Z
A
C
B
0 5000 km
Using the scale bar below as the reference, scribe a circle around the three points using a compass, string, or scrap paper.
3600 km
Distance to the Epicenter
3,600 km
5,000 km
7,600 km
Station
A
B
C
Scribe the arc for Station A using the map scale distance
$Z
$Z
$Z
A
C
B
0 5000 km
NSF Funded CUNY GK-12 Science NOW Project
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
The two circles cross at two points. A third circle is needed to confirm the earthquake epicenter.
5000 km
Distance to the Epicenter
3,600 km
5,000 km
7,600 km
Station
A
B
C
Scribe the arc for Station B using the map scale distance
$Z
$Z
$Z
A
C
B
0 5000 km
NSF Funded CUNY GK-12 Science NOW Project
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
3600 km
All three arcs must pass through the earthquake epicenter, in this case, the San Andreas fault in California, USA.
Using scrap paper.
Distance to the Epicenter
3,600 km
5,000 km
7,600 km
Station
A
B
C
If the distance is longer than the scale, use scrap paper to extend the scale.
$Z
$Z
$Z
A
C
B
0 5000 km
NSF Funded CUNY GK-12 Science NOW Project
Finding the Epicenter of an Earthquake Using the Difference in Time Between the P and the S Wave
3600 km
All three arcs must pass through the earthquake epicenter, in this case, the San Andreas fault in California, USA.
Using scrap paper.
Where the three arcs cross is the epicenter – Circle it!
