1.
Ages:
~ LPI EDUCATION/PUBLIC OUTREACH SCIENCE ACTIVITIES ~
SUBDUCTING PLATE GRAPHS
6th grade and up
Duration:
Based on “Real Evidence of a Subducting Plate” by McLelland and Martin 30 minutes
OVERVIEW —
Materials:
One large copy of map
of South America for
the class, or a regular
sized map for each
group of students
Per group of 2-5
students
• Set of earthquake
data for a specific
range of latitudes
• Student data
sheets
(optional) image of the
3D subduction plate
boundary from
http://rses.anu.edu.au/
seismology/projects/R
UM/slabs/slabs.html
The students will graph earthquakes along the west coast of South America to create a
graphic outline of the shape of the subducting plate.
OBJECTIVE —
The students will:
• Graph the longitude and depth of earthquakes in South America
• Use the graph to visualize the descending slab of oceanic crust at this subduction
boundary
• Compare the graphs for various latitudes and describe their similarities and
differences
The students should be familiar with the concepts of plate
tectonics, subduction, and the relationship between subduction and earthquakes.
BEFORE YOU START:
ACTIVITY —
This activity could be done individually, with each student creating a graph, or in
groups. It can be done in conjunction with the 3D modeling activity “Real Evidence
of a Subducting Plate”.
1. Show the students the map of South America. Ask them whether they’ve heard
of any earthquakes on that continent. Where did they occur? (Earthquakes
often occur in Peru and Chile, along the west coast.)
2. Explain to the students that they will be graphing the earthquakes depth
compared to their longitude, in order to get a better picture of the plate
boundary.
3. Arrange the students into pairs or groups, and hand out copies of the datasets
and data sheets A and B (one each per group). Explain that they will be
graphing the depth so that the numbers are increasing as you descend (zero is
near the top of the graph). Explain that to match the map, they will be graphing
west longitude so that it decreases to the right.
4. Ask the students to describe the two different data sheets—why would they use
sheet A? Why would they use sheet B? Invite them to examine their data to
determine which is better for their dataset.
5. After the students have finished creating their graphs, invite them to compare
their data to another group’s data.
How do they compare? Why might some of the graphs look different from
others? How could we determine if the graphs should all have the same
pattern?
[The data are each for different parts of South America, each with its own
individual characteristics. To determine if the different patterns are errors,
students could re-graph the data; or additional data could be gathered.]
Discussion questions
•
Do you see a pattern in some of the graphs? What is the pattern?
•
What do you notice about the depth of the focus of the earthquakes as you go further inland from the
coast of South America?
What appears to be happening to the two plates that meet along the west coast of South America,
according to your model?
Describe the type of plate boundary which you think is present along the west coast of South America.
How can our model explain the deep trench that lies just off the coast of South America?
•
•
•
Show the students the three dimensional model of the subducting plate from the website.
TIES
TO STANDARDS —
Texas Essential Knowledge and Skills for Science
Science Concept Standards
6(10) Earth and space. The student understands the structure of Earth, the rock cycle, and plate tectonics.
The student is expected to:
(C) identify the major tectonic plates, including Eurasian, African, Indo-Australian, Pacific, North
American, and South American; and
(D) describe how plate tectonics causes major geological events such as ocean basins,
earthquakes, volcanic eruptions, and mountain building.
8(9) Earth and space. The student knows that natural events can impact Earth systems. The student is
expected to:
(B) relate plate tectonics to the formation of crustal features;
Group 1 Earthquake Data
Lat
-17.84
-21.11
-18.98
-19.11
-21.16
-21.26
-21.09
-20.83
-21.09
-21.03
-21.14
-20.43
-20.28
-18.89
-20.55
-21.17
-18.07
-18.88
-18.66
-18.08
-18.08
-18.97
-17.04
-18.24
-18.06
-19.55
-17.02
-20.38
-17.34
-19.92
-20.04
-18.05
-18.41
-18.34
-17.30
Lon ▾
Group 2 Earthquake Data
Depth (km)
66.64
67.23
67.39
67.47
68.13
68.20
68.21
68.33
68.35
68.39
68.53
68.64
68.70
68.75
68.80
68.91
68.99
69.09
69.14
69.26
69.32
69.46
69.52
69.66
69.68
69.74
70.03
70.17
70.23
70.36
70.49
70.53
70.71
71.21
72.59
269.0
145.0
142.0
190.0
92.0
117.0
139.0
132.0
109.0
117.0
97.0
111.1
116.7
131.0
105.0
123.0
146.0
107.0
104.0
108.0
136.0
86.0
139.6
132.5
124.3
35.0
95.0
35.0
81.0
34.0
38.0
37.0
34.8
45.0
36.3
Lat
-26.79
-28.18
-26.38
-28.91
-27.58
-28.09
-28.09
-28.76
-28.67
-28.56
-29.19
-29.32
-30.26
-30.23
-29.13
-28.13
-28.42
-28.23
-27.14
-27.90
-27.95
-28.50
-29.38
-29.39
-29.59
-27.14
-28.38
-29.98
-29.59
-29.87
-29.47
-30.06
-29.92
-29.93
-27.86
-26.80
-30.00
Lon ▾
63.21
63.22
64.58
64.59
65.83
66.52
66.54
66.86
67.54
68.12
68.16
68.48
69.02
69.27
69.82
70.40
70.67
70.70
70.72
70.72
70.82
70.86
70.96
71.03
71.11
71.23
71.35
71.38
71.46
71.53
71.55
71.58
71.62
71.92
72.26
72.54
72.66
Depth (km)
559.9
554.9
10.0
65.0
26.8
188.0
155.7
7.4
132.2
117.7
43.5
46.2
36.2
89.0
102.6
78.4
35.0
57.4
40.0
67.0
42.0
51.8
81.6
62.0
44.0
22.8
34.0
39.4
35.0
50.0
35.1
30.2
31.3
31.7
35.0
16.0
31.8
Group 3 Earthquake Data
Lat
-23.27
-21.81
-22.84
-22.70
-22.86
-22.63
-22.27
-21.96
-22.53
-23.29
-22.70
-22.25
-21.79
-22.88
-23.07
-22.06
-22.78
-22.33
-22.23
-22.88
-22.02
-21.87
-22.07
-21.81
-21.86
-22.30
-22.06
-22.73
-21.80
-22.05
-22.84
-23.23
-23.02
-22.65
-22.73
-21.95
Lon ▾
70.66
70.20
68.99
68.91
68.91
68.83
68.80
68.80
68.76
68.74
68.68
68.67
68.64
68.52
68.51
68.51
68.46
68.41
68.33
68.32
68.32
68.24
68.18
68.16
68.07
67.77
67.48
67.41
67.16
66.76
66.65
66.56
66.32
66.19
66.14
65.76
Depth (km)
35
26.8
95
35.9
96.5
114.1
100.9
111
73
97.3
112.2
95.2
144.6
99
114.7
107.2
137.2
98.1
114
35
112.9
92
120
95
102.7
204.8
122
231.5
185.7
163
193.6
238.9
208
260.5
232.2
246.6
Group 4 Earthquake Data
Lat
-34.74
-34.32
-34.74
-31.82
-33.98
-34.00
-34.23
-33.94
-34.01
-34.01
-34.15
-33.96
-33.93
-34.25
-33.86
-33.64
-33.62
-33.68
-34.73
-34.38
-34.72
-32.82
-33.60
-34.72
-34.75
-34.71
-34.72
-33.80
-34.76
-32.57
-34.66
-34.71
-34.66
-31.85
-31.30
-31.68
Lon ▾
73.72
73.39
72.97
72.73
72.34
72.34
72.33
72.32
72.31
72.31
72.30
72.29
72.26
72.20
72.05
72.00
71.99
71.92
71.88
71.86
71.85
71.84
71.83
71.83
71.82
71.80
71.76
71.75
71.72
71.61
71.53
71.47
71.36
70.23
68.28
67.97
Depth (km)
10.0
16.0
28.0
35.0
30.0
33.0
15.0
35.0
24.0
30.0
9.0
35.0
35.0
21.7
68.8
27.0
25.0
25.6
32.0
35.0
27.0
38.0
30.0
39.2
39.0
35.0
43.0
38.0
47.0
35.0
46.0
47.0
64.0
101.0
104.0
94.0
Group 5 Earthquake Data
Lat
-25.02
-25.68
-25.62
-24.90
-24.19
-24.69
-23.89
-23.85
-23.90
-23.74
-24.06
-23.66
-24.21
-24.29
-24.19
-24.43
-24.25
-25.80
-25.82
-24.08
-25.81
-24.06
-25.87
-23.87
-24.05
-25.71
-23.65
-23.83
-25.02
-24.87
-24.92
-24.65
-24.86
-24.69
-24.80
-23.76
Lon ▾
72.10
70.67
70.59
70.30
70.25
69.82
69.41
69.18
68.53
67.71
67.60
67.35
67.18
67.10
67.03
67.03
66.90
66.88
66.81
66.78
66.74
66.70
66.66
66.66
66.63
66.62
66.57
66.52
65.75
65.60
65.53
65.49
65.42
65.39
65.23
64.96
Depth
(km)
35
49.5
17
38.8
28
49
96.9
82
104.3
235.8
220
251.8
217.1
157.6
192
160.9
172
43.6
63.8
194
10
178.4
35
203.2
190.9
10
200.8
149
24.4
10
10
61.4
39.4
24
35
18
Student Data Sheet A
Latitudes range from ________ to _________
Earthquake Depth vs Longitude
0
Depth (km)
100
200
300
400
500
600
75
73
71
69
Longitude (Degrees W)
67
65
63
Student Data Sheet B
Latitudes range from ________ to _________
Earthquake Depth vs Longitude
Longitude (Degrees W)
75
0
Depth (km)
50
100
150
200
250
300
73
71
69
67
65
63