GLG 112 Final
How many meters are in one kilometer?
1,000
Choose the best description of the landscape where the highest run-up height was recorded.
A wide river valley with a bridge running over it
How do geologists study earthquakes in the geologic record?
All of the above
P-waves are generated by which of the following types of earthquakes?
All of the above
The top diagram in Figure 6 shows earthquakes along a length of the San Andreas Fault before October 17, 1989 and the one on the bottom shows earthquakes along the same fault after that date. These two cross sections illustrate that:
All of the above
What evidence exists that provides clues that plate tectonics is occurring?
All of the above
Which of the following are potential sources of destruction that may be caused either directly or secondarily by earthquakes?
All of the above
How would Figure 5 change if the seismic station was further away from the epicenter?
All of these options
Choose the rheological layer that flows slowly, causing the Earth's lithospheric plates to move, and creating tectonic activity
Athenosphere
Of the diagrams below, which one best represents convection in the mantle that drives plate motion?
B
Which direction is the oceanic plate moving?
B
Which letter in Figure 2 represents the epicenter of the earthquake?
B
On the cross section, which type of rock are you most likely to find at #8
Basalt
What rock has small crystals and is igneous?
Basalt
What is the upper oceanic crust primarily composed of, and where is it formed?
Basalt; at divergent boundaries
Which type of plate boundary is not associated with earthquakes?
None of the above. Earthquakes occur at all plate boundaries
Choose the best answer that explains the distribution of known impact craters.
North America has many known impact craters because it is densely populated with relatively well-funded research.
What type of lithosphere will subduct and why?
Oceanic because it is thinner and denser
Where is the hot spot currently located in the map of islands above? Ma means Millions of years ago.
Island A
What hazard related to earthquakes are the suburban homes most at risk from?
Landslides
The crust of Plate W is _________ than the crust of Plate X.
Less dense
A city is built in a wide, flat valley surrounded by mountains. In the summer, people like to go hiking in the mountains and take pictures of the beautiful, crystalline rock outcrops. The trails are steep, but worth the view. Streams run from the mountains into the city, where there is a large lake lined with a clay and silt substrate. The multi-story buildings in the city center are built of concrete slabs, while the homes in the suburbs (in the foothills and in the mountains) are newer wood-frame houses. What hazard related to earthquakes is the city-center most at risk from?
Liquefaction
The outer core is:
Liquid
Put the rheological layers of the Earth in order from outside (surface of the Earth) to inside (center of the Earth)
Lithosphere, asthenosphere, lower mantle, outer core, inner core
Which of the following earthquake scenarios would have the highest intensity at the epicenter (with all other things being equal)?
M8. Shallow focus (5 km). Urban epicenter. City is built on sedimentary rock.
New crust created at ocean ridges records the polarity of Earth's magnetic field. These magnetic reversal support the Theory of Plate Tectonics because:
Magnetic minerals, like iron, in the crust of the same age on either side of a spreading center have the same polarity because the crystals solidified from magma aligned with the earth's magnetic field, therefore that crust must have been created at the same time.
All of these except 1 are found at convergent boundaries. Which is NOT found there?
Mid-ocean ridge
What are the characteristics of a region at the highest risk for a tsunami?
Next to and across an ocean from a subduction zone
Oceanic crust is mostly younger than 200 million years old (Ma). Continental crust ranges from 0 Ma to over 3800 Ma. Why is there such a large difference in the oldest age of the two types of crust?
Oceanic crust subducts and disappears into the mantle, but continental crust remains on the surface.
On the cross-secction, where would be the safest place to avoid volcanoes and earthquakes?
On the coast of Plate Y
Seismic waves that travel by compressing the material they are moving through are referred to as:
P wave
What seismic wave can be used as a warning signal to shut down high-speed trains and gas lines?
P-wave
What type of fault is pictured in Figure 1?
Reverse Fault
When do rocks along a fault have the highest amount of stored strain?
Right before an earthquake
This seismic wave can only travel through solid matter.
S wave
What area would rank higher on the Intensity scale?
San Francisco Bay
You are in Santa Cruz, CA and you've just experienced an earthquake. You noticed the time between the first vertical jolt and intense shaking was approximately 30 seconds. After the earthquake you call a friend who lives near San Francisco Bay. Your friend noticed that the shaking didn't start for approximately 1 minute after the vertical jolt. You friend reports that there is severe damage to many buildings near the bay, while the area around you has escaped with relatively little damage. Was the earthquake epicenter closer to Santa Cruz or San Francisco Bay?
Santa Cruz
Figure 3 shows three seismogram records of the same earthquake recorded at three different cities. For each city, the record begins on the left and time increases to the right. Only body waves are shown on these seismograms. Use this diagram to answer questions 10-12. Based on the seismograms in Figure 3, which city was closest to the epicenter of the earthquake?
Seattle, Washington
Which city experienced the greatest intensity based on the seismograms in Figure 3?
Seattle, Washington
Secondary (S) waves cannot travel through liquids or gases. Why?
Secondary waves shear material, and this motion cannot occur in liquids or gases
What type of stress would create the fault in Figure 4?
Shear
What side went down relative to the other in Figure 1?
Side A
What side is the hanging wall in Figure 1?
Side B
Was the recorded wave height larger or smaller than the run-up height?
Smaller
The mantle is almost entirely
Solid
What is earthquake magnitude?
The approximate shaking intensity during an earthquake
Some of the buildings in Mexico City are at risk for collapsing during an earthquake. What makes this city particularly susceptible to building collapse, when compared to other major cities?
The city is built on material deposited in an ancient lake bed
Large meteorite impacts on Earth can cause all of the following EXCEPT:
The climate becoming warmer
Why are ocean ridges higher in elevation than the surrounding crust?
The crust at mid-ocean ridges is hotter, slightly less dense and lifted by ridge push from below.
There is a seismic gap along the San Andreas Fault in southern California. What does this mean?
The next "big one" is likely to occur on this section of the fault
Which city experienced the greatest magnitude based on the seismograms in Figure 3?
They all experienced the same magnitude
What do all plate boundaries have in common?
They are made up of faults
What area would rank higher on the Moment Magnitude scale?
They would both be equally ranked on this scale
On the cross section, Plate W is moving:
To the right, toward Plate X
What type of plate boundary is presently located along the San Andreas fault in California?
Transform
One warning sign of an impending tsunami is the water will withdrawal quickly from the shoreline.
True
Read this short synopsis of the Tohoku earthquake and answer questions 58-60. The 2011 Tohoku earthquake caused a tsunami event in Japan that hadn't been seen in 1,000 years. The maximum run-up height was 147 ft (~45 m) and the tsunami travelled far inland in some areas (around 8 km). While the earthquake that caused this tsunami was a M9.1, the waves were actually much bigger than predicted. In some places, the tsunami easily overtopped walls that had been built to protect seaside villages. True or False: The region where the tsunami traveled the furthest inland must have been a wide, flat area or a river.
True
Tsunami are not necessarily dangerous because of their wave height, but because of their wavelength.
True
On the cross-section at #6, how is magma formed?
Water from the subducting lithosphere lowers the melting temperature of the lithosphere.
Which type of ground material or substrate will shake with the greatest intensity during an earthquake?
Water-saturated sediment
Most (normal) waves are generated by what process?
Wind
Which of the factors below affects the timing, height, and run-up of a tsunami wave?
all of the above
You and a friend are exploring around Flagstaff. There are over 600 volcanoes in northern Arizona, but you've also heard that there is at least one noteworthy meteor crater. Your friend excitedly calls you over. They've found a crater! What evidence could you look for to determine if this crater is from a meteorite impact or from a volcanic explosion?
b & c
The _________________ the water, the slower a tsunami will move.
shallower
What is the deformation that results from stress called?
strain
The moment magnitude of an earthquake is calculated using all of the following measurements EXCEPT ________.
the amount of slip along the fault
Which of the following factors does NOT affect the intensity of ground shaking?
the type of fault
On the cross section, what feature is located at #1?
Continental shelf
Some continents continue outward below sea level, forming long, submerged areas of shallow water called:
Continental shelves
A meteorite with a mass of 100 grams and a volume of 20 centimeters3 has a density of:
100 grams / 20 centimeters3
What type of plate boundary can create the highest magnitude earthquake?
Convergent boundaries because plate motion causes most rocks to be compressed
If you find a plate boundary along the edge of an ocean next to a continent, what type of plate boundary is it most likely to be?
Convergent with subduction
You discover another planet with two types of crust that are of equal thickness. Crust A has a density of 3.8 g/cm3 and crust B has a density of 4.1 g/cm3. Which crust would you expect to subduct?
Crust B
The lithosphere is made up of what two rigid layers?
Crust and upper mantle
Identify the general fault type represented in Figure 1.
Dip-slip
Which tectonic process formed the Red Sea, a long, narrow body of water east of Egypt?
Divergence
On the cross section, what type of plate boundary is located at #8?
Divergent
What is the best description of a passive margin?
A coastline where there is no tectonic activity
The Haitian earthquake in 2010 was an example of:
A disaster
Why does the age of the Hawaiian island chain get progressively older from southeast to northwest?
A hot spot is creating the islands. As the Pacific Plate moves over the hot spot, the islands are rafted away in the direction of plate motion.
What was the cause of the tallest tsunami ever recorded?
A landslide
The lower mantle is:
A plastic solid
At oceanic divergent zones,
A ridge forms an area of high elevation
What is the rheology of the lithosphere?
A rigid solid- it can fracture or break
Which of the following DOES NOT explain the differences between locations of impact events and known impact craters on Earth?
Earth's age of 4.5 million years is too young to have experienced meteorite impacts in some areas of the planet.
Describe the pattern of earthquakes and volcanoes around Earth's surface.
Earthquakes and volcanoes occur in bands and belts that circle the Earth, but can be randomly located in some places. Earthquakes may occur with volcanoes, but volcanoes do not always occur with earthquakes.
What direction is the Nazca Plate subducting?
East
What location is at the least risk for an earthquake?
East Coast of South America
What quick process during/after an earthquake may result in a significant change in ground elevation (either up or down)?
Elastic Rebound
The further you are from the epicenter of an earthquake, the safer you are.
False
The oceanic lithosphere is thicker than the continental lithosphere
False
Tsunami are created by all undersea earthquakes.
False
Seismic waves slow down when they travel through less dense rock (rock with pore space or sediment). What effect does this have?
Ground shaking is lessoned
The only major rock type to form from the solidification of molten rock is
Igneous
If you're standing on the beach and you feel a strong earthquake, which of the following should you do?
Immediately go to high ground away from the beach
Tsunami waves have the longest wavelength ______________ and the highest amplitude _________________.
In the deep ocean; in the deep ocean
How many types of plate boundaries are shown?
3
On the cross section, where are you most likely to find volcanism related to subduction?
3
Which of the following will NOT cause a tsunami?
An earthquake on a strike-slip fault at a divergent boundary
What is an aftershock?
An earthquake that occurs after a main shock along the area of fault that ruptured during the main shock
Where are you most at risk for earthquakes AND volcanic eruptions?
Andes Mountains, South America
Choose the correct name and location of the impact event that contributed to the extinction of the dinosaurs
Chicxulub, Yucatan, Mexico Chelyabinsk, Russia
Which part of this city will shake the most during an earthquake?
City center
At a convergent zone, most stresses are:
Comoressional
What type of stress would form the fault in Figure 1?
Compressional
Which type of plate boundary is not usually associated with volcanoes?
Continent-continent convergent
Earthquake magnitudes, timing, and location are predictable.
False
If you are standing at the scarp created by a powerful earthquake along a dip-slip fault, then you are as close to the focus as you can possibly be. (In other words, the fault scarp is the location on Earth's surface closest to the focus.)
False
Meteorites are usually denser than basalt
False
New crust is created at Transform plate boundaries.
False
On the cross section, there is a plate boundary between #1 and #9?
False
Why do P-waves move faster than other seismic waves?
P-waves compress and expand the material they are moving through
What controls the rheology of Earth's layers?
Pressure and temperature
The tectonic setting of ________ is primarily defined by a transform boundary
Southern California
Choose the most at risk location for tsunami:
Southern coast of Alaska
Choose the correct order of processes that generate an earthquake on a fault:
Stress applied - strain accumulates - rocks break - rocks rebound
Which seismic wave in Figure 5 had the highest amplitude?
Surface wave
Which mountain range is formed by subduction along the west coast of South America?
The Andes Mountains
Meteorites can come from all the following sources EXCEPT:
The sun
If you were on a ship in the middle of the deep ocean when a tsunami passed under you, which of the following statements would be true?
you probably wouldn't even notice the tsunami