Download Review for the Earthquake and Mountain Building Quiz! Here is a

Review for the Earthquake and Mountain Building Quiz!
Don’t forget to review:
The left-hand side of your notes
Your homework, labs and any quizzes for this unit
The key concepts, key vocabulary, section headers, illustrations and review questions from the book
Any documents posted on your class web site
To succeed with this test, you should be able to:
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Describe the cause of earthquakes.
List the types of seismic waves and describe their motion.
Describe how an earthquake epicenter is located.
Describe the worldwide distribution of earthquake epicenters (usually but not always along plate boundaries!).
Explain how the magnitude of an earthquake is determined (Richter Scale).
List the other destructive forces that can be triggered by an earthquake (liquefaction, shaking, fires, tsunamis).
7. Describe Earth's interior structure and composition and how earthquakes help us learn about it.
8. Discuss how rocks become deformed and uplifted
9. Tell the difference between folds, faults and domes and how they form mountains.
10. Describe mountain building associated with convergent plate boundaries.
11. Describe the process of isostasy and the role of isostatic adjustment during crustal uplifting.
Here is a summary of what we covered in this unit. You need to know the details also!
Earthquakes are vibrations of the Earth produced by the release of energy from rocks that rupture because they have
been stressed beyond their limit. This energy, which takes the form of waves, radiates in all directions from the
earthquake's underground source, called the focus. The movements that produce most earthquakes occur along large
fractures called faults that are associated with plate boundaries.
Two main groups of seismic waves are generated during an earthquake: 1) surface waves, which travel along the
outer layer of Earth; and 2) body waves, which travel through Earth's interior.
Body waves are divided into primary, or P, waves, which push (compress) and pull rocks in the direction the wave is
traveling, and secondary, or S, waves, which "shake" the particles in rock at right angles to their direction of travel. P
waves can travel through solids, liquids, and gases. Fluids (gases and liquids) will not transmit S waves. In any solid
material, P waves travel about 1.7 times faster than S waves.
Surface waves are Love waves (side-to-side) and Rayleigh waves, the Rolling waves that make people seasick.
The location on Earth's surface directly above the focus of an earthquake is the epicenter. An epicenter is determined
using the difference in speed of P and S waves, and triangulation.
There is a close correlation between earthquake epicenters and plate boundaries.
Using the Richter scale, the magnitude of an earthquake is estimated by measuring the amplitude (maximum size) of
the largest seismic wave recorded, using a seismograph. Each increase of 1 in the Richter Scale means 31x more
energy released.
The factors that determine the amount of destruction from an earthquake are the magnitude of the earthquake and how
close quake is to a populated area. Structural damage from earthquake vibrations depends on several factors, including
1) how powerful the shaking is, 2) how long the shaking continues, 3) the material upon which the structure rests
(liquefaction of loose soil, longer traveling of seismic waves through firm rock), and 4) the design of the structure.
Secondary effects of earthquakes include tsunamis, landslides, ground subsidence (sinking), and fire.
Research to predict earthquakes is underway in Japan, the United States, China, and Russia—countries where
earthquake risk is high. No consistent method of short-range prediction has yet been devised. Long-range forecasts are
based on the premise that earthquakes are repetitive or cyclical. Seismologists study the history of earthquakes for
patterns, so their occurrences might be predicted.
As indicated by the behavior of P and S waves as they travel through Earth, the four major zones of Earth's interior
are the 1) crust (the very thin outer layer), 2) mantle (a rocky layer located below the crust, 3) outer core (which
exhibits the characteristics of a liquid), and 4) inner core (a solid metallic sphere).
The continental crust is primarily made of granitic rocks, while the oceanic crust is of basaltic composition.
Ultramafic rocks are thought to make up the mantle. The core is composed mainly of iron and nickel.
The crust and uppermost mantle form Earth's cool rigid outer shell called the lithosphere. Beneath the lithosphere lies
a soft, relatively weak layer of the mantle known as the asthenosphere.
One of the most basic geologic structures associated with rock deformation are folds (flat-lying sedimentary and
volcanic rocks bent into a series of waves). The two most common types of folds are anticlines (A!), formed by the
upfolding, or arching, of rock layers, and synclines (Sink!), which are downfolds.
Domes are circular folds formed by massive intrusions of magma. Think of the granite mountains north of here.
Faults are fractures in the crust along which movement has occurred. The movement can be vertical (either up or
down depending on whether the rocks are being squeezed together or pulled apart), or horizontal, like along the San
Andreas Fault
Major mountain systems form along convergent plate boundaries. Andean-type mountain building along continental
margins involves the convergence of an oceanic plate and a plate whose leading edge contains continental crust. At
some point in the formation of Andean-type mountains a subduction zone forms along with a continental volcanic arc.
Continental collisions, in which both plates are carrying continental crust, have resulted in the formation of the
Himalaya Mountains. Continental collisions also formed many other mountain belts, including the Appalachians.
Earth's less dense crust floats on top of the denser rocks of the mantle, much like wooden blocks floating in water.
The concept of a floating crust in gravitational balance is called isostasy. Most mountainous topography is located
where the crust has been shortened and thickened. Therefore, mountains float on deep, roots. As erosion lowers the
peaks, isostatic adjustment gradually raises the mountains in response. (As the mountain weighs less it floats up, just
like a boat rises when you get out of it.) The process of uplifting and erosion will continue until the mountain block
has eroded away.