Earth Science Name: ___________________________

Tectonics Exam Date: __________

1 Most inferences about the characteristics of 3 The study of how seismic waves change as they
Earth’s mantle and core are based on travel through Earth has revealed that
(1) well drillings from Earth’s mantle and core (1) P-waves travel more slowly than S-waves
through Earth’s crust
(2) comparisons between Moon rocks and Earth (2) seismic waves travel more slowly through the
rocks mantle because it is very dense
(3) chemical changes in exposed and weathered (3) Earth’s outer core is solid because P-waves
metamorphic rocks are not transmitted through this layer
(4) Earth’s outer core is liquid because S-waves
(4) the behavior of seismic waves in Earth’s are not transmitted through this layer
interior

2 Approximately how long does an earthquake 4 The observed difference in density between
P-wave take to travel the first 6500 kilometers continental crust and oceanic crust is most likely
after the earthquake occurs? due to differences in their
(1) 6.5 min (3) 10.0 min (1) composition (3) porosity
(2) 8.0 min (4) 18.5 min (2) thickness (4) rate of cooling

Base your answers to questions 5 through 7 on the map below. The map shows the locations of deep-sea
core drilling sites numbered 1 through 4. The approximate location of the East Pacific Ridge is shown by a
dashed line. Point A is located on the East Pacific Ridge.

Map of Drilling Sites

Central 20∞ N
America
cific Ridge

2 4 0∞
a

1 3
st P
Ea

A South
America
Pacific Ocean
20∞ S

140∞ W 120∞ W 100∞ W 80∞ W

5 At point A, the East Pacific Ridge is the bound- 7 Compared to the thickness and density of the
ary between the oceanic crust of the Pacific floor, the continental
(1) Cocos Plate and the North American Plate crust of South America is
(2) South American Plate and the Nazca Plate (1) thinner and less dense
(3) Pacific Plate and the South American Plate (2) thinner and more dense
(4) Pacific Plate and the Nazca Plate (3) thicker and less dense
(4) thicker and more dense
6 At which drilling site would the youngest igneous
bedrock most likely be found?
(1) 1 (3) 3
(2) 2 (4) 4
 Base your answers to questions 8 through 11 on the diagram and map below. The diagram shows three
seismograms of the same earthquake recorded at three different seismic stations, X, Y, and Z. The distances
from each seismic station to the earthquake epicenter have been drawn on the map. A coordinate system has
been placed on the map to describe locations. The map scale has not been included.

Seismograms

Noon
S
P
Station X
S
P
Station Y
S
P
Station Z
Noon

Time scale 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
(minutes
after noon)

A B C D E F G H I J
1 Ocean 1
X
2 2

3 3

4 4

5 Z 5
Y
6 6

7 7

8 8

9 Continent 9

A B C D E F G H I J

8 Approximately how far away from station Y is the 10 Seismic station Z is 1,700 kilometers from the
epicenter? epicenter. Approximately how long did it take the
(1) 1,300 km (3) 3,900 km P-wave to travel to station Z?
(2) 2,600 km (4) 5,200 km (1) 1 min 50 sec (3) 3 min 30 sec
(2) 2 min 50 sec (4) 6 min 30 sec
9 The S-waves from this earthquake that travel
toward Earth’s center will 11 On the map, which location is closest to the epi-
(1) be deflected by Earth’s magnetic field center of the earthquake?
(2) be totally reflected off the crust-mantle (1) E–5 (3) H–3
interface (2) G–1 (4) H–8
(3) be absorbed by the liquid outer core
(4) reach the other side of Earth faster than
those that travel around Earth in the crust
 Base your answers to questions 12 and 13 on the reading passage and map of the western United States
below and on your knowledge of Earth science. The states of Washington and Oregon have been labeled on the
map. The plate boundary shown on the map is the source area for high-magnitude earthquakes in Washington
and Oregon. Two hazardous zones associated with these earthquakes are also shown.

Washington and Oregon Earthquakes

Large-magnitude earthquakes have occurred in Washington and Oregon as a result of
crustal movement along thrust faults bordering the coasts of these states. Thrust faults
occur when one section of Earth’s crust slides over another section. Associated with the sud-
den movement of these thrust faults, coastlines can drop several feet, flooding forests with
saltwater. Geologists have discovered evidence from various geologic ages of flooded coastal
forests in the bedrock layers of Washington and Oregon. They have also found layers of
sandstone thought to have been derived from sand deposits left by tsunamis. Using the rock
record, scientists conclude that very large magnitude earthquakes occur every 300 to 500
years with the most recent large quake occurring about 200 years ago.

Canada

Plate Washington
boundary
Yellowstone Hot Spot
Oregon

Pacific Ocean

Key

High-hazard zone

Low-hazard zone

12 a What is a tsunami?
b State how tsunamis can affect coastal regions.

13 a Identify the tectonic plates on both sides of the plate boundary shown on the map.

b Identify the type of tectonic plate boundary shown on the map that is responsible
for the thrust faults along the Washington and Oregon coastline.
14 A seismic station in Massena, New York, recorded the arrival of the first P-wave at
1:30:00 (1 hour, 30 minutes, 00 seconds) and the first S-wave from the same earth-
quake at 1:34:30.
a Determine the distance, in kilometers, from Massena to the epicenter of this earth-
quake.

b State what additional information is needed to determine the location of the epi-
center of this earthquake.

15 Earth’s outer core is best inferred to be 16 The large coal fields found in Pennsylvania
(1) liquid, with an average density of approxi- provide evidence that the climate of the north-
mately 4 g/cm3 eastern United States was much warmer during
(2) liquid, with an average density of approxi- the Carboniferous Period. This change in climate
mately 11 g/cm3 over time is best explained by the
(3) solid, with an average density of approxi- (1) movements of tectonic plates
mately 4 g/cm3 (2) effects of seasons
(4) solid, with an average density of approxi- (3) changes in the environment caused by humans
mately 11 g/cm3 (4) evolution of life

Base your answers to questions 17 and 18 on the diagram below, which shows models of two types of earth-
quake waves.

Model A Model B

17 Model B best represents the motion of earth- 18 The difference in seismic station arrival times of
quake waves called the two waves represented by the models helps
(1) P-waves (compressional waves) that travel scientists determine the
faster than S-waves (shear waves) shown in (1) amount of damage caused by an earthquake
model A (2) intensity of an earthquake
(2) P-waves (compressional waves) that travel (3) distance to the epicenter of an earthquake
slower than S-waves (shear waves) shown in (4) time of occurrence of the next earthquake
model A
(3) S-waves (shear waves) that travel faster than P-
waves (compressional waves) shown in model A
(4) S-waves (shear waves) that travel slower than
P-waves (compressional waves) shown in
model A
20 On the map below, line AB is drawn across several of Earth’s tectonic plates in the South Atlantic Ocean.

South American
Plate

Scotia A
Plate

Sandwich
Plate Antarctic
Plate

Which cross section best represents the plate boundaries and mantle movement beneath
line AB?

Key

Ocean
Lithosphere
Mantle

A B A B

(1) (3)
A B A B

(2) (4)