GEOL1301 - Exam #2
Where do earthquakes occur?
Along faults in the lithosphere
How does paleomagnetism support the seafloor spreading theory?
Known ages of reversals of the magnetic field preserved in continental rocks were correlated with reversal patterns found on the ocean floor.
Match the fault type to the plate boundary it is most commonly associated with.
Normal --> Divergent Reverse --> Convergent Strike-slip --> Transform
Characterize these faults by matching them to their relative movement.
Normal --> The block above the inclined fault moves down Reverse --> The block above the inclined fault moves up Thrust --> The block above the low-angle inclined fault moves up Strike-slip --> One side of the fault moves horizontally past the other
The contracting Earth model hypothesis was used by early scientists to explain the different features on Earth's surface. Which of the following were parts of this possible explanation?
Ocean basins are formed due to surface collapse. All features on Earth are approximately the same age. Mountain belts result from Earth cooling and contracting over time.
We know that Earth is not growing in size, yet new crust is created constantly at oceanic ridges. What is happening at subduction zones in order to create a balance?
Oceanic lithosphere is consumed and pulled into the mantle.
Compare the three types of convergent plate boundaries by matching each with its description.
Oceanic-oceanic - Subduction produces a volcanic island arc. Oceanic-continental - Subduction produces a chain of volcanoes on the continent. Continental-Continental - Collision produces a high mountain range with little volcanic activity.
What does the pattern of colors representing the age of ocean crust on either side of the Mid-Atlantic Ridge demonstrate?
The youngest ocean crust is next to the ridge, and gets successively older to the west and east.
What is the physical relationship between the geographic and magnetic north poles?
They are usually in different places, as the magnetic pole does move.
What happens to rocks on both sides of a fault as stresses are building up over time?
They become distorted
What ocean floor feature marks the process of subduction
Trench
True or false: Typical movement during an earthquake within a fault system occurs along a segment of a single fault.
True
True or false: The geographic and magnetic north poles are in different locations.
True: (Reason: the two poles are in different locations. The geographic north pole at 90° north and the magnetic north pole currently at approximately 85° north (it moves)
Which of the following describe the process of magma formation at subduction zones?
Water related from the subjected oceanic lithosphere moves into the overlying plate and induces it to melt
Alfred ______ was the first person to develop and publish a sound explanation for the origin of the continents and oceans.
Wegener
The Hawaiian Islands are associated with ______.
a mantle plume not on a plate boundary
What is a fault?
a zone of weakness in the lithosphere along with movement occurs
A continental margin that coincides with a plate boundary is called ______, whereas a continental margin that is not a plate boundary is called ______.
active; passive
deep earthquakes
are associated with subduction zones
shallow earthquakes
are the most common
Where is the Ring of Fire, so called because of the numerous active volcanoes found there?
around the edge of the pacific ocean
Tectonic plates move _____
at different yet steady rates
Earthquakes are common at plate _______ because this is where faults are common.
boundaries
A new divergent boundary begins by ______.
breaking apart a continent
While the size of an earthquake has a strong relationship with the damage it creates, human factors such as ______ codes and public awareness also are involved.
building
Which human factors are most directly associated with how many people are killed by earthquakes?
building codes and public awareness
A hot spot on Earth's surface is created ______.
by a mantle plume
Seafloor spreading predicted that the age of seafloor rocks gets older with distance from the oceanic ridge. Patterns of reversals were compared with those in continental rocks, which had been dated, and ______ the prediction
confirmed
The historic idea called ______ ______says that Earth once had a supercontinent named Pangaea that has broken up and moved over time.
continental drift
Of the three types of convergent plate boundaries, which is known for its absence of volcanic activity?
continental-continental-convergence
As shown in this figure, the process of ______ within Earth's mantle transfers heat energy from the core to the surface and drives plate motion.
convection
Heat is transferred through Earth's mantle by the process of ______, and is the driving force causing tectonic plates to move.
convection
The contracting Earth model was used to explain Earth's different features as resulting from Earth ______ over time.
cooling and shrinking
At oceanic ridges, solid asthenosphere close to the surface melts due to ______, creating magma that rises to the surface and become new ocean crust.
decompression
What type of plate boundary is created as hot, rising mantle material causes plates to move apart?
divergent
Normal faults are common along _____ plate boundaries, reverse faults are common along _____ boundaries, and strike-slip faults are common along ______ boundaries.
divergent; convergent; transform
The frequency of _____ decreases with depth at subduction zones because the lithosphere warms up and loses its brittleness.
earthquakes
Most ______ occur on ______ located at ______.
earthquakes; faults; plate boundaries
True or false: All tectonic plates move at the same rate.
false
Pieces of lithosphere move past each other along zones of weakness called ______
faults
The location on the fault where an earthquake occurs is the _____, , while the place on the surface directly above this is the ______.
focus; epicenter
The place on a fault that is the source of an earthquake is the ______, while the location directly above on Earth's surface is the ______.
focus; epicenter
In support of his continental drift theory, Wegener used matching features such as rocks, ______ , and mountains on separate continents, as well as the fit of the continents, and evidence of past ______
fossils; glaciation or glaciers
In support of his continental drift theory, Wegener used matching features such as rocks, ______ , and mountains on separate continents, as well as the fit of the continents, and evidence of past _____
fossils; glaciers
When a mantle plume reaches Earth's surface, it forms a(n) _____ spot.
hot
Most transform plate boundaries occur ______.
in conjunction with oceanic divergent boundaries
Plate tectonic theory explains that large-scale geologic processes such as earthquakes and volcanoes result directly and primarily from ______.
interactions at plate boundaries
The time necessary to build up enough stress to break a fault is called the recurrence _____.
interval
Which of the three seismic stations is farthest from the earthquake, and how do you know? (Choose one location and one explanation.)
lime; because the interval between the P-wave and S-wave arrival times is the longest
The release of energy that is an earthquake occurs in Earth's ______ along faults.
lithosphere
Divergent plate boundaries are created where hot rock rises from the
mantle or asthenosphere
Most earthquakes
occur along plate boundaries
The ______ system is a long, continuous feature on the ocean floor that has a zipper-like appearance, is volcanic in origin, and is relatively shallow.
oceanic ridge
The creation of magma at ______ occurs due to decompression; the hot, less-dense magma rises and creates new ocean crust.
oceanic ridges
In order to achieve a balance in the size of Earth, new lithosphere is created at ______ and destroyed at ______.
oceanic ridges; subduction zones
Varying and vast amounts of data collected ______ in the 1900s provided a mechanism for continental drift.
on the seafloor
A fault system consists of individual faults; during an earthquake, typically movement occurs ______.
only along part of a single fault
The Ring of Fire describes the active volcanoes located around the edge of the _______ ocean
pacific
A fundamental change in our understanding of a basic concept is called a(n) ______ shift
paradigm
What is the name of the theory that explains the connection between plate boundaries with large-scale geologic processes such as mountain building, earthquakes, and volcanoes?
plate tectonic theory
The fastest seismic waves are _____ waves
primary
The ______ interval is the time between successive earthquakes on the same fault.
recurrence
A fault _____ is shown on this image as indicated by the arrows
scarp
Information collected from the seafloor in the early and mid-1900s included heat flow, earthquakes, volcanic activity, and age and magnetic properties of rocks; this lead to the idea of _____ spreading which provided a mechanism for continental _____
seafloor; drift
The two forms of _____ waves are body and surface waves
seismic
The device used to detect an earthquake is called a(n) ______, , while the record of the waves recorded is called a(n) ______.
seismograph; seismogram
Most earthquakes are _____ in depth and occur at plate ______.
shallow; boundaries
Earth's lithosphere is broken into eight major ______ plates.
tectonic
Melting of rocks occurs due to an increase in _____, a decrease in _____ , and in some situations, the introduction of hot _______
temperature pressure water
The difference in arrival time between P and S waves is used to calculate ______ an earthquake.
the distance from a seismic station to
The majority of earthquakes occur at shallow depths in subduction zones because this is where ______.
the lithosphere is brittle and cold
How does the age of the ocean floor change from an oceanic ridge toward a continent?
the rocks get older
Which of the following describe oceanic trenches?
they are long and deep
Plates horizontally slide past each other at ______ boundaries
transform
Plates horizontally slide past each other at ______ boundaries.
transform
What is the name of the feature on the ocean floor, indicated by the arrow, that clearly indicates subduction is occurring?
trench, ocean trench, or oceanic trench
What is the name given to a series of high ocean waves generated by an earthquake on the seafloor?
tsunami
Which of the following describe the oceanic ridge system?
volcanic; in shallower water than the abyssal plains
The addition of _____ from the descending oceanic plate in a subduction zone lowers the melting temperature of the overlying mantle rocks and induces them to melt to form magma
water
What is a tsunami?
A series of high ocean waves generated by vertical movement on the seafloor
True or false: The Hawaiian Islands are formed by a plate boundary
False
True or false: Transform plate boundaries occur only within continental crust.
False
What is the German meteorologist Alfred Wegener known for?
He developed the continental drift theory
What is the source of energy that drives Earth's lithospheric plates to move?
Heat flow from Earth's interior
Below are listed characteristics of passive and active margins. Choose those exclusive to active margins.
- The west coast of North America is an example - This area is characterized by volcanoes and earthquakes - The continental margin is also a plate boundary
Which of the following describe transform plate boundaries?
- crust is neither created nor destroyed - plates slide past each other in opposite horizontal directions - they are referred to as conservative plate boundaries
Earth's ______ is divided into ______ tectonic plates. (Choose the two answers that best fit.)
- eight major and a few smaller - lithosphere
The energy for plate movement comes from ______.
- heat left over from the planet's formation - decay of radioactive isotopes
Oceanic trenches are narrow, deep, and located ______.
- next to volcanic island arcs - next to continents
Which of the following provide evidence used by Wegener to support his continental drift theory?
- similar mountain belts on separate continents - similar fossils on separate continents - paleoclimate data - the apparent "puzzle piece" fit of the continents
What are the major ideas included in the seafloor spreading theory?
- the high evaluation of oceanic ridges results from the erupted hot magma - new oceanic lithosphere is continuously created oceanic ridges - the seafloor moves away from the ridge in a conveyor belt-like style
What has to occur in order to melt a rock?
- the introduction of water - an increase in temperature - a decrease in pressure
Describe the birth and development of a divergent boundary by putting the sentences in the correct order, with the earliest step on top.
1. Continental lithosphere begins to break apart 2. A Rift Valley forms and eventually widens 3. New ocean floor is created and seawater flows in to create a new, narrow ocean 4. The narrow ocean widens and matures over millions of years
Describe the deformation of rock before and after an earthquake by putting the steps in the correct order, with the first step on top.
1. Stress builds along the fault 2. rocks bend and distort 3. the amount of stress overcomes the strength of the fault 4. an earthquake occurs
Match the geographic location with the tectonic plate
A - North American plate B - Pacific plate C - South American plate D - African plate E - Eurasian plate F - Indian-Australian plate
Identify the faults shown here
A --> Normal fault B --> Reverse fault C --> Strike-slip fault
What is a paradigm shift?
A fundamental change in the way we view a basic concept
What is a fault scarp?
A scar created by the intersection of a fault plane and Earth's surface
What is the name of the idea developed by Alfred Wegener describing how all of Earth's continents had once existed in a single landmass called Pangaea and have since moved to their current positions?
Continental drift
Match the name of the tectonic plate with its geographic location.
Pacific plate - over the pacific ocean North American plate - Over North America and east into the Atlantic Ocean; also extends over much of the upper Northern Hemisphere African plate - Over Africa, and west into the Atlantic Ocean and east into the Indian Ocean Nazca plate - Over the southeastern Pacific, west of South America Eurasian plate - Over Asia and Europe, including Indonesia, and the northeastern Atlantic