Download Subduction Boundary Earthquake Depth

Lab #_____
Name: _____________________________________________________________ Date: ________________ Period: _____
3. On the graph below plot the data for
Boundary
Lab
Tonga Subduction
trench from the
table. DO
NOT
CONNECT THE DOTS. Instead draw
a Best –fit line for the points. A BestIntroduction:
fit line is a line that does not go
The vast majority of earthquakes occur at plate boundaries. The
through the points but shows a trend
deepest earthquakes occur at subduction boundaries where
of data.
lithosphere is plunging down into the mantle. Deep focus earthquakes
! Assume the line is the upper
are defined as those with foci (plural of focus) occurring deeper than
surfacehave
of a foci
subducting
300 kilometers. Shallow earthquakes
less than plate.
70 kilometers
E
Ea
arrtth
hq
qu
ua
ak
ke
eD
De
ep
p
Tonga trench
deep, while intermediate!focus
earthquakes
occur at location
depths between
Label
the approximate
of
70 and 300 kilometers. In this the
lab activity,
you
will
plot
actual
Tonga trench on the graph
earthquake foci data from an area where subduction is currently
Using
yourinReference
tables,
occurring. This area is the!Tonga
Islands
the southwest
Pacific.
indicate the name of the two
converging plate
Procedure:
! Using your Reference tables,
1. Look at Earthquake Depth Data Table (on the right). Place colored
indicate the relative movement of
dots next to the depths using one color for shallow quakes, one for
each plate using arrows
intermediate, and one for seep. Determine the number of shallow
(<70), intermediate (70-300)
deep
(>300)
earthquakes
occurring
! and
Using
your
Reference
tables,
at the Tonga Trench and record
them the
all on
theof
summary
table below.
indicate
type
crust that
makes up each plate.
SUMMARY TABLE
4. Make a 2nd graph for the Chile trench.
Earthquake Type
Focus Depth
Tonga Trench
Plot the Chile data… and again draw
your
best-fit
line.
Shallow
Less than
70 km
! Assume the line is the upper
surface
Intermediate
70-300
km of a subducting plate.
Deep
! Label the approximate location of
More than 300 km
the Chile trench on the graph
To t a l n u m b e r o f e !
a r tUsing
h q u a kyour
e s Reference tables,
indicate the name of the two
converging
plate foci for the data
2. On the graph on page 2, plot
the earthquake
presented in the table. Use
same
colors
as abovetables,
to plot the points
! the
Using
your
Reference
on the chart. Use one color for
shallow,
one
for
intermediate,
indicate the relative movementand
of one
for deep. DO NOT CONNECTeach
THE DOTS!
draw a Best-fit line for
plate Instead
using arrows
the points. A Best-fit line is a line that does not go through the points
! Using your Reference tables,
but shows a trend of data.
➡
indicate the type of crust that
Assume the line represents
the upper
surface
of the subducting
makes
up each
plate.
plate
Label the approximate location of the Tonga Trench on the graph
➡ Using your reference tables, indicate the names of the two
converging plates
➡ Using your reference tables, indicate the relative movement of
the plates using arrows
➡
Boundary Lab
2
Longitude
( °W)
Focus
depth
(km)
176.2
173.8
175.8
174.9
175.7
175.9
175.4
174.7
176.0
175.7
173.9
177.7
174.9
178.5
177.9
179.2
178.7
173.8
178.3
177.0
174.6
178.8
176.8
177.4
173.8
178.0
177.7
174.1
177.7
179.2
178.8
178.1
175.1
178.2
176.0
178.6
174.8
178.2
179.1
177.8
177.0
270
35
115
40
260
190
250
35
160
205
60
580
50
505
565
650
600
50
540
350
40
580
340
420
60
520
560
30
465
670
590
510
40
550
220
615
35
595
675
460
380
C
Long
( °W
67
66
68
69
62
70
61
68
69
66
69
67
67
69
68
67
69
69
63
68
66
68
66
65
67
69
68
67
66
66
68
66
68
65
68
63°
65°
67°
68°
69°
70°
SEA-FLOOR
500
400
300
Depth in Km
200
100
0
180°
66°
Chile trench
64°
174°
175°
176°
177°
600
179°
178°
700
Tonga Trench
173°
62°
172°
61°
171°
60°
170°
Lab #_____
Name: _____________________________________________________________ Date: ________________ Period: _____
Lab #_____
Name: _____________________________________________________________ Date: ________________ Period: _____
ANALYSIS AND CONCLUSION
1. Using the reference tables, identify the following as a convergent, divergent or transform
boundary:
a. Mid Atlantic ridge ________________________________
b. Tonga trench ___________________________________
c. Aleutian trench __________________________________
d. East Pacific Rise ________________________________
e. Great Rift Valley ________________________________
f. San Andreas Fault ______________________________
2. Which tectonic plate is being subducted at the Tonga trench?
___________________________________
3. Compare the distances of the Tonga Trench and Chile Trench from the East Pacific Rise, which
is closer and which is farther?
______________________________________________________________________________________________
______________________________________________________________________________
4. If the East pacific rise is the source of new rock, which trench would contain the oldest rock?
Why?
______________________________________________________________________________________________
______________________________________________________________________________
5. At which type of plate boundary do we find the deepest Quakes? (Circle the correct answer)
TRANSFORM
SUBDUCTION
6. As a plate subducts deeper into the mantle, what happens to the depth of the quakes?
______________________________________________________________________________________
7. Which type of plate boundary creates new ocean crust?
_______________________________________
8. From looking at your reference tables where do we usually find divergent boundaries?
______________________________________________________________________________________
______________________________________________________________________________________
8. Which Geographic features are most associated with subduction zones?
_______________________________________
9. What is the relative movement of the plates along the San Andreas Fault? What type of
boundary is it?
______________________________________________________________________________________