seismic waves reading assignment

A magnitude 7 earthquake has an amplitude ______ times greater than a magnitude 4 earthquake. 10,000 300 30 1,000

1,000

The earthquake with the largest moment magnitude calculated to date was the _______ earthquake. 1960 Chile 2011 Japan 1964 Alaska 2004 Sumatra

1960 Chile

Examine this graph. If the S-P time is approximately 4.5 minutes, how far from the epicenter are you? 5,000 km 7,000 km 1,000 km 3,000 km

3,000 km

Examine this nomograph. If it is determined from a seismograph that the S-P time is 30 seconds and the amplitude of the seismic waves is 0.5 mm, what is the magnitude of the earthquake? 1.0 3.5 2.0 6.5

3.5

The amount of energy released by a magnitude 5 earthquake is ______ times that released by a magnitude 4 earthquake. 10 3,800 48 162

48

A fault-rupture length of 10 km produces approximately a magnitude ____ earthquake.

6

What is the largest moment magnitude ever recorded? Multiple choice question. 9.5 11.0 10.6 9.0

9.5

The acceleration due to gravity is ______, which is referred to as 1.0 g. 32 m/sec2 9.8 m/sec2 1.5 m/sec2 196 m/sec2

9.8 m/sec2

Which building is likely to have the longest period? A 35-story skyscraper A single-story family home A 15-story office building A five-story apartment building

A 35-story skyscraper

What is a fault? A fracture in bedrock along which sliding has occurred A fracture in bedrock A fracture in bedrock across which no shear displacement has occurred A planar feature that separates one rock type from another

A fracture in bedrock along which sliding has occurred

Why does it often take weeks to determine the moment magnitude for great earthquakes? Because the mathematics involved in determining the moment magnitude are incredibly complex and require massive computing capacity Because seismograms from at least 150 seismometers are required to accurately determine the amplitude of the seismic waves Because the area of the rupture zone is defined by aftershocks, which continue for many weeks following a great earthquake Because great earthquakes typically occur in remote locations where it is difficult to get to the site of fault rupture

Because the area of the rupture zone is defined by aftershocks, which continue for many weeks following a great earthquake

Which type of seismic wave is the fastest? Love wave Surface wave Acoustic wave Body wave

Body wave

How do scientists identify the depth to the top of the asthenosphere in the Earth's interior? P waves slow down and S waves speed up. P waves speed up and S waves slow down. Both P and S waves slow down. Both P and S waves speed up.

Both P and S waves slow down.

How is earthquake magnitude measured? Using sensors buried within the fault zone By satellites that can detect the energy released and measure its magnitude By analyzing the seismic wave traces on a seismogram From reports about the intensity of shaking and damage

By analyzing the seismic wave traces on a seismogram

Where do high-frequency seismic waves cause the most damage? Anywhere that the bedrock is particularly solid Close to the epicenter Close to bodies of water Far from the epicenter

Close to the epicenter

According to the law of superposition, which of the layers marked in this image is the oldest? A B D C

D

True or false? Low-frequency seismic waves tend to die out first, at shorter distances from the hypocenter.

False

Which of the following best describe an S wave? Has a shearing motion The second to reach a recording station Can travel through any material Cannot travel through fluids Has a push-pull motion

Has a shearing motion The second to reach a recording station Cannot travel through fluids

Why is the Richter magnitude scale less reliable for large earthquakes that occur far away? S-P times are harder to calculate for very large earthquakes. It only uses surface waves. It uses short-period seismic waves. Seismometers can't pick up seismic waves from great distances.

It uses short-period seismic waves.

Surface waves are referred to as ______ waves because they take more time to complete one cycle of motion and are the slowest moving. X (extreme) S (slow) T (tertiary) L (long)

L (long)

Which of these laws tells us that when a sedimentary rock layer abruptly terminates, something must have happened to it after it formed. Law of superposition Law of topography Law of original continuity Law of original horizontality

Law of original continuity

Which law of physical geology can be used to determine that these rocks layers were deformed into folds after they were deposited? Law of cross-cutting relationships Law of original continuity Law of original horizontality Law of superposition

Law of original horizontality

Which of these correctly describe the nature of surface waves? Low frequency High frequency Slow-moving Fast-moving

Low frequency Slow-moving

The ______ Scale is a descriptive scale based upon the effects of an earthquake on people and buildings. Richter Magnitude Mercalli Intensity Did-You-Feel-It? Moment Magnitude

Mercalli Intensity

Why is it of greater concern to design buildings to withstand horizontal ground movement than it is to design them to withstand vertical ground movement? It is much cheaper to strengthen a building in the horizontal plane that it is to strengthen it vertically. L waves, which move side to side, are much stronger than Rayleigh waves, which move up and down. Most buildings are already designed to handle the vertical forces associated with their own weight. Most earthquakes only result in horizontal ground movement because Rayleigh waves are rare.

Most buildings are already designed to handle the vertical forces associated with their own weight

Which of the following describe a primary (P) wave? Cannot travel through fluids Has a shearing motion Moves in a push-pull fashion Can travel through any material Slower than surface waves The first to reach a recording station

Moves in a push-pull fashion Can travel through any material The first to reach a recording station

Why might two adjacent buildings that are constructed of the same materials but have different heights suffer very different amounts of damage during an earthquake? A building constructed of low-quality materials is more likely to collapse than one constructed of high-quality materials. They experience very different amounts of ground movement and acceleration due to their different heights. One may have the same period as the seismic waves and thus experience resonance.

One may have the same period as the seismic waves and thus experience resonance.

The drastic decrease in P wave velocity and the disappearance of S waves at the depth shown with an arrow on this graph marks the top of which layer of the Earth's interior? Asthenosphere Outer core Inner core Lithosphere Mantle

Outer core

This figure demonstrates how ______ waves move through material. Love Rayleigh S P

P

The body-wave (mb) scale for earthquake magnitude is based on the amplitudes of _______. Rayleigh waves with 18- to 22-second periods S waves with 0.1- to 2-second periods P waves with 1- to 10-second periods Love waves with 18- to 22-second periods

P waves with 1- to 10-second periods

This figure demonstrates the sense of motion of which type of seismic wave? Rayleigh wave S wave P wave Love wave

Rayleigh wave

The surface-wave (Ms) scale for earthquake magnitude is based on the amplitudes of ______. P waves with 1- to 10-second periods S waves with 1- to 2-second periods Love waves with 18- to 22-second periods Rayleigh waves with 18- to 22-second periods

Rayleigh waves with 18- to 22-second periods

This image best illustrates the way in which ______ waves travel through material. surface P S Rayleigh

S

The arrival times of which two types of seismic wave are used to calculate the location of an earthquake's epicenter? S wave P wave Love wave Rayleigh wave

S wave P wave

Why is the shaking during an earthquake stronger in a building built upon soft sediments? It is harder to build a strong foundation for a building on soft sediments. Seismic waves slow down in soft sediments, which increases their amplitude. S waves cannot pass through soft sediments and therefore exit the ground where they are found. Soft sediments reflect seismic waves, creating many new seismic waves.

Seismic waves slow down in soft sediments, which increases their amplitude

What is the S-P time? The difference in arrival times of body waves and surface waves The break in shaking after S waves arrive and before P waves arrive The time during which a seismometer records both S and P waves The difference in arrival time of S waves and P waves

The difference in arrival time of S waves and P waves

Why are aftershocks common after a large earthquake? It takes a while for the seismic waves to reverberate around Earth. It takes many small earthquakes to equal the energy released by a large, mainshock earthquake. The energy of a large earthquake is too great to release in one burst and so is released in smaller, sequential bursts. The movement along the fault increases stress on adjacent sections of that fault.

The movement along the fault increases stress on adjacent sections of that fault

Why are aftershocks common after a large earthquake? It takes a while for the seismic waves to reverberate around Earth. It takes many small earthquakes to equal the energy released by a large, mainshock earthquake. The movement along the fault increases stress on adjacent sections of that fault. The energy of a large earthquake is too great to release in one burst and so is released in smaller, sequential bursts.

The movement along the fault increases stress on adjacent sections of that fault.

Why do S waves disappear at the core-mantle boundary? The outer core is liquid, and S waves cannot travel through a liquid. S waves are more likely to be reflected at a boundary between materials of significantly different density. S waves lose velocity as they travel into the Earth and generally come to a stop before reaching the great depth of the core-mantle boundary. When they reach the outer core, P waves and S waves combine to form a different type of seismic wave, called an L wave.

The outer core is liquid, and S waves cannot travel through a liquid

Why do geologists map the location of active faults? To predict when the next earthquake will occur To find old faults that might move in the future To predict the size of the next earthquake To assess earthquake hazards

To assess earthquake hazards

The rate of change in velocity of the ground as it is moved by seismic waves is called ____.

acceleration

Acceleration during an earthquake is usually measured relative to _______. the force of compression the frequency of seismic waves the velocity of ground movement acceleration due to gravity

acceleration due to gravity

The movement associated with an earthquake puts stress on adjacent faults and causes ____.

aftershocks

The Richter magnitude scale uses the _______ of seismic waves to determine the amount of shaking and thus the size of an earthquake. frequency arrival times wavelength amplitude

amplitude

The decrease in velocity of both P and S waves at about 100 km depth marks the top of the ____.

asthenosphere

Seismic waves that pass through the interior of the planet are called ____ waves, whereas those that travel across the surface are called ____ waves.

body, surface

The velocity of P waves depends on the ______ and _______ of the material through which they pass. compressibility density magnetism epicenter

compressibility density

P waves are ______ and can travel through air, just like sound waves do, and hence are audible. transverse compressional fast slow

compressional

A building constructed of ______ is likely to have a shorter period. steel wood bamboo concrete

concrete

Using the S-P time from a single seismograph, it is possible to determine the ______ the epicenter. location of direction to distance from and direction to distance from

distance from

A(n) ____, is the vibrations we feel when sudden movement occurs along a fault.

earthquake

An earthquake occurs from the release of ______ when stress on a fault builds high enough for the rocks to snap and move suddenly. movement heat energy

energy

Seismic waves travel ____ through hard rocks than they do through soft rocks and sediment.

faster

A ____ is a planar feature where the two sides move past each other. If no movement occurs, then the planar feature is called a ____.

fault, fracture

Faults can be recognized in the field, even if the fault plane itself is not exposed, because ______. earthquakes occur along faults faults offset rock units faults generally lie in valley floors faults create small linear mountain chains

faults offset rock units

Smaller earthquakes that precede the mainshock are called ____, and those that follow the mainshock are called ____.

foreshocks, aftershocks

The number of waves passing a given point during one second is referred to as ______. period wavelength amplitude frequency

frequency

S waves can travel through ______. granite rock mudstone water molten magma air

granite rock mudstone sandstone

P wave velocity depends upon the material through which the wave passes. Rank these materials from the fastest P wave velocity at the top to the slowest at the bottom. loose sand water air packed sand granite rock

granite rock packed sand loose sand water air

Short rupture lengths produce mostly ______ seismic waves. high-frequency low-frequency moderate-frequency

high-frequency

Similar to sound waves passing through a trombone, the shorter the rupture length along a fault, the ______ the frequency of the seismic waves that are generated. higher lower shorter longer

higher

The damage done to this house was most likely due to ________. liquefaction of soft soil horizontal ground movement vertical ground movement passage of P waves

horizontal ground movement

Seismographs like the one shown here record seismic waves because the heavy weight does not move with the framework of the instrument. This is due to the _____ of the weight. size motion inertia location

inertia

The principle of ____, explains that a stationary object will remain stationary unless acted upon by an external force.

inertia

Because of their low frequency and slow speed, surface waves carry _____ amounts of energy away from the epicenter. small moderate large

large

Earthquake magnitude is strongly influenced by the ________. length of fault rupture duration of shaking types of rock at the surface population density close to the epicenter

length of fault rupture

The location of the epicenter and hypocenter of an earthquake can be determined by ______. finding the place on the ground where the fault ruptured measuring the amplitude of P waves and S waves and calculating the difference between them looking at the difference in arrival times of different types of seismic waves looking at how the intensity of shaking varies from one place to another

looking at the difference in arrival times of different types of seismic waves

This type of surface wave travels parallel to Earth's surface in a side-to-side motion.

love

The two types of surface wave are ____ waves and ____ waves.

love, rayleigh

Similar to a rupturing fault, when the path of sound waves through a trombone is extended the frequency is ______ and the tone is lower. lower higher shorter vibrating

lower

The greater the length of fault rupture, the ____ the frequency of the seismic waves it produces.

lower

To determine the _______ of an earthquake, seismologists use a nomograph, which compares the distance from the hypocenter and the amplitude of the seismic waves. intensity magnitude duration location likelihood

magnitude

____ is a measure of the the amount of energy released during an earthquake.

magnitude

The largest earthquake in a series that occurs on the same portion of a fault is called the ____.

mainshock

Seismic ____ (Mo) is equal to the shear strength of rocks times the rupture area of the fault times the average displacement on the fault.

moment

The _______ scale is the most accurate measure of the size of large earthquakes. moment magnitude (Mw) Richter magnitude (ML) surface-wave scale (Ms) body-wave scale (mb)

moment magnitude (Mw)

The Richter magnitude scale is only useful for assessing earthquakes that _______. occur nearby have a duration of one minute or longer are moderate in size are a magnitude 8 or larger have an epicenter at least 3,000 km away

occur nearby are moderate in size

The law of ____ ____ states that sedimentary layers extend laterally until they thin out at their edges.

original continuity

The law of ________ states that sediments deposited in water form as horizontal layers. lateral continuity original horizontality cross-cutting relationships superposition

original horizontality

For a wave, the ____ = 1/frequency.

period

The amount of time it takes for a building to sway back and forth one time is called its ______. resonance return interval frequency period

period

The two types of body waves are ____ waves and ____ waves.

primary, secondary

If, during an earthquake, you feel like you're being rocked in a boat at sea, you are most likely feeling the passage of ____ waves.

rayleigh

Because their motion is up and down and side to side, ____ waves are the type of body wave that can do severe damage to buildings.

secondary (s)

The second type of seismic wave to reach a recording station after an earthquake is a(n) ____ wave.

secondary (s)

Another term for an earthquake is a ______. spasm seism shiver slippage

seism

The energy released when a fault ruptures radiates outward from the hypocenter as ____ ____.

seismic waves

The instrument used to record seismic waves is called a(n) _____. shake meter earthquake map seismograph inertia recorder

seismograph

The study of earthquakes is known as _____.

seismology

The instrument used to detect seismic waves is called a(n) ____.

seismometer

Wave frequency and period are related. The higher the frequency, the ____ the period.

shorter

P waves can travel through air, where they take the form of ____ waves. You might experience this as a sonic boom.

sound

The law of ____ states that within a sequence of undisturbed sedimentary, the oldest layer is at the bottom.

superposition

The most reliable measure of earthquake size is seismic moment, which measures the ________. the amount of strain energy released by the movement along the rupture surface the amount of movement along the entire length of the fault amplitude of all seismic waves, both body and surface and long- and short-period variations in severity of shaking with distance from the fault rupture and with rock type

the amount of strain energy released by the movement along the rupture surface

Charles Richter based his earthquake magnitude scale on the idea that _______. the farther from an earthquake, the greater the shaking of Earth the bigger the earthquake, the greater the shaking of Earth the difference in arrival times of P and S waves increases with distance from the epicenter the deeper the earthquake, the longer the duration of shaking at the surface

the bigger the earthquake, the greater the shaking of Earth

To study earthquakes, seismologists must record the movement of earthquake waves in ______ directions. four two ten three

three

What is the minimum number of seismograms needed to determine the location of the epicenter of an earthquake?

three

The ______ nature of S waves make them apt to damage buildings. Multiple choice question. transverse longitudinal slow fast

transverse

Love waves are a type of surface wave. They are similar to S waves in that they ____________. travel with a shearing motion at right angles to their direction of advance cannot travel through fluids but can travel through solid material are extremely fast-moving travel with a push-pull motion parallel to their direction of advance can travel through both fluids and solids

travel with a shearing motion at right angles to their direction of advance cannot travel through fluids but can travel through solid material

The distance between two waves, labeled A in this figure, is called the ____. The height of a wave above its starting point, labeled B in this figure, is called the ____.

wavelength, amplitude