chapter 5

True or false: Data from a single seismograph can be used to locate an earthquake.

False

True or false: Tsunami waves move slowly across the open ocean.

False

Which two types of data are included in modern techniques for measuring earthquake magnitude that are not used in the Richter method?

Fault movement Rock properties

Tsunami waves are fast and long. Choose the answer that best describes the maximum speed and the answer that best describes the height of the waves at the coast recorded for recent tsunami events. (Select two answers total.)

Tens of meters Nearly 1,000 km/hr

The two forms of _____waves are body and surface waves.

seismic

How much warning time will the upcoming human earthquake warning system provide for those close to the epicenter?

10 seconds

An increase from one division to the next (i.e., from a 7 to an 8) on the earthquake magnitude scale represents a ______-fold increase in shaking and ______ times the amount of energy released.

10; 32

Megathrust earthquakes on the Cascadia subduction zone occur, on average, every ______.

500 years

What is the difference between a seismograph and a seismogram?

A seismograph detects seismic waves and creates a record of them called a seismogram.

What is a tsunami?

A series of high ocean waves generated by vertical movement on the seafloor

Where do earthquakes occur?

Along faults in the lithosphere

Below are listed qualities of different body waves. Choose all those that describe primary waves.

Also known as P waves Are the highest-velocity waves Compress the material they travel through

The two forms of seismic waves include___ waves that travel through Earth's interior and____ waves that travel along Earth's surface.

Blank 1: body Blank 2: surface

The two forms of seismic waves include______ waves that travel through Earth's interior and______ waves that travel along Earth's surface.

Blank 1: body Blank 2: surface

The location on the fault where an earthquake occurs is the________ while the place on the surface directly above this is the___________

Blank 1: focus or hypocenter Blank 2: epicenter

The device used to detect an earthquake is called a(n) , while the record of the waves recorded is called a(n)

Blank 1: seismograph Blank 2: seismogram

Most earthquakes are _______ in depth and occur at_______

Blank 1: shallow Blank 2: boundaries

Which of the following describe the earthquake magnitude scale?

Each division represents a 32 times increase in energy. A jump of 1 on the scale reflects 10 times as much ground motion. It is logarithmic.

What are aftershocks? Multiple choice question.

Earthquakes that occur on the same fault following the main earthquake

What is the reasoning for the Great Southern California Shakeout?

For people and emergency services to prepare and practice in order to mitigate the damage done from the inevitable earthquake that will occur

The Modified___scale measures the intensity of earthquakes.

Mercalli

Strike-slip

One side of the fault moves horizontally past the other.

The___ method for measuring earthquakes is not commonly used today because it does not account for deep earthquakes, large earthquakes, and earthquakes that occur at large distances from the recording station.

Richter

Forests of cedar trees were destroyed in a massive tsunami that the Japanese recorded to have occurred on January 26, 1700. What other types of information did the dead trees provide to support this specific date?

Scientists used the tree ring patterns to determine the specific month they died.

What two pieces of information do scientists use to determine the distance from a seismic station to an earthquake?

The arrival time of the P waves The arrival time of the S waves

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.

How do ghost forests provide evidence for large earthquakes? Multiple choice question.

The land the trees are on decreases in elevation, seawater invades this land, and the roots drown in saltwater, killing the trees.

How are the records from three seismic stations used to determine the location of an earthquake?

The three distances are represented as circles on a map, and where the three intersect is the location of the earthquake.

What is the minimum number of seismograph stations needed to determine the location of an earthquake?

Three

True or false: Earthquake hazard maps have been constructed using Modified Mercalli scale rankings for both historical earthquakes and for earthquakes occurring in regions not sufficiently covered with seismic recording equipment.

True

True or false: Intensity measurements from a single earthquake range in values.

True

True or false: Typical movement during an earthquake within a fault system occurs along a segment of a single fault.

True

How does liquefaction occur?

Water-saturated sediment is shaken, loses its strength, and changes to a solid-liquid mixture.

Earthquakes that occur after the main shock of an earthquake are called

aftershock

Given the recurrence interval of megathrust earthquakes on the Cascadian subduction zone, and that the last was in 1700, we might expect one to occur ______.

anytime in the next 200 years

Human earthquake warning systems will use the arrival of the first ______ in order to provide just enough time for people to protect themselves from the upcoming shaking.

body waves

Earthquakes are common at plate______________ because this is where faults are common.

boundaries

The measurement of an earthquake's intensity generally ______ with distance from the epicenter.

decreases

Ghost forests in Alaska and Washington were created when a large_________ resulted in the vertical displacement of land, allowing saltwater to inundate and drown the trees.

earthquake

Because many of the world's largest cities are located in tectonically active areas, over 2 million people were killed by ______ in the twentieth century.

earthquakes

The Richter method (and scale) is no longer the method of choice by scientists when measuring earthquakes because it does not accurately measure ______.

earthquakes at large distances from seismic stations large earthquakes deep earthquakes

Even though the Modified Mercalli scale is based on subjective data, it can be useful in measuring ______.

earthquakes that occur in regions lacking seismographs historical earthquakes

Most ______ occur on ______ located at ______.

earthquakes; faults; plate boundaries

Modern techniques for measuring earthquake magnitude rely upon the same data as the Richter method does, but also take into account rock properties and___ plane movement.

fault

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

The time necessary to build up enough stress to break a fault is called the recurrence

interval

The Modified Mercalli scale ______. Multiple select question.

is based on damage to buildings and human experiences measures the intensity of earthquakes ranks earthquakes using Roman numerals

The Modified Mercalli scale ______.

is based on damage to buildings and human experiences ranks earthquakes using Roman numerals measures the intensity of earthquakes

A common hazard associated with earthquakes are_____ , which are created when unstable, steep slopes are shaken.

landslides

What is the name of the process that occurs as water-saturated sediments are shaken during an earthquake and lose their strength, resulting in surfaces that collapse or buildings that tip over?

liquefaction

The release of energy that is an earthquake occurs in Earth's ______ along faults.

lithosphere

The magnitude of an earthquake is a measure of ______. Multiple choice question.

the energy it releases

The___ of an earthquake measures the amount of energy released, and the subsequent amount of shaking that occurs.

magnitude

Buildings constructed on softer materials shake ______ those on bedrock.

more than

In the continental United States, approximately ______ of the population live in areas that experience damaging earthquakes.

one-half

A fault system consists of individual faults; during an earthquake, typically movement occurs ______.

only along part of a single fault

Of the two types of body waves, which is the faster and compresses the material through which it moves? (Use a single word for your answer.)

primary

The ______ interval is the time between successive earthquakes on the same fault.

recurrence

During the Great Southern California_____ , people and emergency services prepare and practice what to do during and after an earthquake.

shakeout

The difference in arrival time between P and S waves is used to calculate ______ an earthquake.

the distance from a seismic station to

The magnitude of an earthquake is a measure of ______.

the energy it releases

What is the name given to a series of high ocean waves generated by an earthquake on the seafloor?

tsunami

Written records in Japan and dendrochronology work in Washington and Oregon were combined with other evidence to support a massive earthquake that created a ______ on January 26, 1700.

tsunami

The uplift of mountains by 1 foot during the Northridge earthquake is an example of ______ change.

vertical

The ______ associated with earthquakes can cause land that was previously submerged to become uplifted above sea level, as exemplified by 1 to 3 meters of motion that exposed coral reefs during the 2004 Sumatra earthquake.

vertical motion

Landslides are created by earthquakes ______.

when unstable materials on steep slopes are shaken