The Edges
of Plates
Topic
Plotting geologic activity shows that the edges of the tectonic plates are
places of intense geologic activity.
Introduction
Earthquakes and volcanoes, examples of geologic activity, do not happen
everywhere. Most volcanoes and earthquakes occur near the edges of
tectonic plates where the Earth’s crust is going through dramatic
changes. Along some plate boundaries, one plate is being pushed under
another, destroying part of the existing crust. At other plate boundaries,
new crust is being created from molten lava forced to the Earth’s surface.
In other places, two plates are sliding past each other horizontally, and
crust is not produced or destroyed.
Time Required
60 minutes
Materials
✒
✒
✒
✒
world map showing tectonic plates
red pencil
green pencil
science notebook
Safety Note
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Please review and follow the safety guidelines.
THE EDGES OF PLATES
2
Procedure
60º
60º
Figure 1
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150º
75º
Equator
120º
90º
60º
30º
0º
30º
60º
90º
120º
150º
30º
0º
0º
30º
30º
30º
75º
2.
Look over Data Table 1 (page 3) which lists the severe earthquakes
that have occurred over a period of 2 years. Find each earthquake’s
position on the world map (Figure 1) by locating the point at which
its latitude and longitude come together. Mark the location of each
earthquake with a red pencil.
Look over Data Table 2 (page 5) which lists volcanoes that have
occurred in a 3-month period in 2003. On the same world map,
locate each volcano. Mark the location of each volcano with a dot
using the green pencil.
60º
1.
THE EDGES OF PLATES
3.
3
When you have all of the dots in place, examine the map carefully
and use it to answer the Analysis questions on page 6.
3 earthquakes in
Data Table 1: Locations of large
2002 and 2003
Earthquake
Degrees
latitude
Degrees
longitude
Date
1
–10
160
Jan. 1, 2003
2
18
–104
Jan. 22, 2003
3
51
178
Mar. 17, 2003
4
39
141
May 26, 2003
5
2
129
May 26, 2003
6
–7
–72
June 20, 2003
7
–3
68
July 17, 2003
8
–61
–43
Aug. 4, 2003
9
–45
167
Aug. 21, 2003
10
42
144
Aug. 21, 2003
11
42
144
Sep. 25, 2003
12
42
144
Sep. 25, 2003
13
51
88
Sep. 27, 2003
14
–17
168
Jan. 2, 2002
15
37
70
Feb. 2, 2002
16
6
124
Mar. 5, 2002
17
24
122
Mar. 31, 2002
18
13
145
Apr. 26, 2002
19
44
131
Apr. 26, 2002
20
–22
–180
Aug. 19, 2002
Data Table 1: Locations of large earthquakes in 2002 and 2003 (continued)
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THE EDGES OF PLATES
4
Data Table 1: Locations of large earthquakes in 2002 and
2003 (continued)
Earthquake
Degrees
latitude
Degrees
longitude
Date
21
–24
179
Aug. 19, 2002
22
–3
143
Sep. 8, 2002
23
–2
134
Oct. 10, 2002
24
3
96
Nov. 2, 2002
25
64
147
Nov. 3, 2002
26
48
146
Nov. 17, 2002
(Data Table 2 follows)
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THE EDGES OF PLATES
5
Data Data
TableTable
2: Severe
volcanoes
over
period
in 2003
2: Severe
volcanoes
overaa 3-month
3-month period
in 2003
Volcano
Degrees
Degrees
latitude
longitude
1
70 S
108 E
October
2
13 N
124 E
October
3
20 N
104 W
October
4
2N
128 E
October
5
15 N
91 W
October
6
19 N
156 W
October
7
56 N
161 E
October
8
0
78 W
October
9
15 N
92 W
October
10
17 N
62 W
October
11
1S
78 W
October
12
13 N
124 E
October
13
54 N
159 E
October
14
12 N
161 E
October
15
2N
128 E
September
16
37 N
15 E
September
17
54 N
159 E
September
18
19 N
99 W
September
19
5S
151 E
September
20
10 N
85 W
August
21
54 N
159 E
August
22
9N
123 E
August
23
1N
125 E
August
24
12 N
86 W
August
25
12 N
43 E
August
26
21 S
56 E
August
27
1S
78 W
August
28
7S
110 E
August
29
1N
127 E
August
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Date, month 2003
THE EDGES OF PLATES
6
Analysis
Where do most earthquakes occur in relation to the edges of
tectonic plates?
2. What generalizations can you make about the locations of
earthquakes?
3. Based on the map and the dots you have placed on it, what do you
think is the cause of most earthquakes?
4. Where do most volcanoes occur in relation to the edges of tectonic
plates?
5. What generalizations can you make about the locations of volcanoes?
6. What do you think is the cause of most volcanoes?
7. Do any earthquakes or volcanoes occur in places that are not
edges of tectonic plates. If so, what might cause these?
8. The theory of plate tectonics says that the Earth’s crust is made of
a thin layer of rigid plates that are moving relative to one another.
Based on this map, do you think that the theory of plate tectonics
can help predict where earthquakes and volcanoes will occur?
1.
What’s Going On?
People who live along tectonic plates are constantly reminded
of the high level of activity going on inside the Earth. One
place where two plates of the Earth’s crust are sliding past
each other is along the San Andreas fault in California. The
San Andreas fault is about 1,300 kilometers long and tens of
kilometers wide in some places. Along this line, the plate that
makes up much of the Pacific Ocean is moving past the plate
that makes up North America at the rate of about 5 cm/year.
As the plates grind past each other, they stick, slide, and
move, causing a motion inside the Earth that people
experience as tremblings or earthquakes.
Want to Know More?
See Our Findings.
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OUR FINDINGS
THE EDGES OF PLATES
Analysis
1. Most earthquakes occurred near the edges of tectonic plates.
2. Earthquakes are more frequent near the edges of tectonic plates.
3. movement of the tectonic plates
4. On this map, most volcanoes occurred near the edges of tectonic
plates.
5. Volcanoes are more frequent near the edges of tectonic plates.
6. movement of magma and tectonic plates
7. Yes; when the crust moves or shifts, the effects can be felt for
thousands of miles.
8. Yes; as scientists track the movement of plates, they develop a
database of information that can help them predict upcoming quakes
and volcanoes.
9. Answers will vary.
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