Download Earthquake Study Guide Key

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Earthquakes & Volcanoes Study Guide
Just completing this study guide is not sufficient. You will also need to study all labs, readings, and your journal.
Lesson 11 – P-waves and S-waves
1. What can be done to make buildings more earthquake safe?
- A foundation firmly connected to solid bedrock.
- Beams and columns strapped together and to the ground with metal, and the floors and roofs are
securely fastened to the walls.
- Brick houses and buildings may be sprayed with liquid concrete and reinforced with steel bracing.
2. How does the type of ground material affect the amount of shaking during an earthquake? Be specific…know when
the ground will shake the most/least.
Moist soils, especially those rich in clay, and loose soils like sand, lose their compactness during an
earthquake. Parts of the soil rotate, acting more like a liquid or gelatin than a solid surface. In earthquake
prone areas, steel posts are driven deep into the solid bedrock to create a secure foundation for the
building.
3. Which waves travel through the body of the earth?
P-waves and S-waves are body waves meaning they travel through the body of the earth.
4. What does the ‘p’ in p-wave stand for?
Primary – these waves arrive first.
5. What does the ‘s’ in s-wave stand for?
Secondary – these waves arrive second.
6. Which wave is the fastest?
P-wave
7. How does each of the 3 waves affect the movement of the ground on the surface?
The p-waves cause vertical (up and down) jolting of the earth’s surface. S-waves cause horizontal (side to
side) movement of the earth’s surface. Some surface waves produce an up and down rolling motion like the
motion you feel when on a boat, while other surface waves move material from side to side.
8. List the waves in order from least destructive to most destructive.
(Least) P-waves, S-waves, Surface waves (Most)
Lesson 12 – Recording Vibrations on Seismograms, with Seismometers and Seismographs
1. What is the focus of an earthquake?
The focus is the point where the earthquake actually occurs (the site of energy release), it can be shallow
or deep in the earth.
2. What is the epicenter of an earthquake?
The epicenter is the point on the earth’s surface directly above the focus. It is usually the place you hear
about in the news when there has been an earthquake.
Skills:
3. Know how to use a seismogram to find the time that the p-wave and the s-wave first arrived at the seismograph
station. (You WILL have to do this on the test.)
4. Know how to find the epicenter of an earthquake if you have earthquake data from 3 different seismograph stations.
(You WILL have to do this on the test.)
5. Know how to find the distance of a location from the epicenter of the earthquake.
(You WILL have to do this on the test.
Lesson 13 – Plotting Earthquakes
1. What does magnitude measure?
Magnitude is determined by measuring the amplitude, or “swing” of the largest seismic wave on the
seismogram. Magnitude measures the total amount of energy released at the focus of the earthquake. A
magnitude 7 earthquake release the same amount of energy always, though the effects might differ based
on where the earthquake occurs.
2. What scale is traditionally used to measure magnitude? Richter Scale
3. Each increase in magnitude number represents a 10-fold increase in energy released.
4. What does intensity measure?
Intensity measures the type of damage done by the earthquake as well as people’s reactions to the
earthquake. It is a measure of the effect of an earthquake on the structures, people and environment. The
intensity of an earthquake may vary depending on where it occurs.
5. What scale is used to measure intensity? Modified-Mercalli Scale
6. What do the locations of earthquakes and volcanoes have in common?
Earthquakes and volcanoes both tend to occur along plate boundaries. The most common area for
earthquakes and volcanoes worldwide is the Ring of Fire (The Circum-Pacific Belt). The Ring of Fire is a
nearly continuous chain of volcanoes around the edges of the Pacific Ocean.
7. What can the locations of earthquakes around the world tell us about the earth’s surface?
Because the locations of earthquakes tend to be along plate boundaries, we can tell that the earth’s surface
is broken into plates that move relative to one another. We can infer the location of plate boundaries by
looking at historical earthquake activity which traces the plate boundaries on earth.
Lesson 14 – Using Earthquakes to Study the Earth’s Interior
1. Draw a diagram and label the inner core, outer core, mantle,
crust.
and
2. How do scientists know the inside of the earth is made of
layers?
Scientists analyze seismic waves to study the inside of
the
earth. As the earthquake waves move through the
different layers of the earth, they change speed and direction based on the properties of that layer.
3. What is one way that scientist know the outer core is liquid?
S-waves cannot travel through liquid, because S-waves also do not travel through the outer core, scientists
can infer that the outer core is liquid.
4. Describe the lithosphere and the asthenosphere.
Asthenosphere
- Upper mantle
- Hot, weak
- Can move
Lithosphere
- Includes the upper mantle and the crust
- Continental and oceanic crusts
- Ridged, solid
- Floats on the asthenosphere