Learnsmart Chapter 5
______ movement along a fault during an earthquake usually is less than 5 meters or less, but megathrust quakes can have 20-40 meters of movement. These movements can happen over ______ distances ranging from hundreds of meters to over a 1,000 kilometers. Horizontal; vertical Vertical; horizontal
Vertical; horizontal
How does liquefaction occur? Water-saturated sediment is shaken, loses its strength, and changes to a solid-liquid mixture. The elevation of land changes from above to below sea level following an earthquake. Sediments within a fault are ground under pressure because of fault movement and are literally "juiced."
Water-saturated sediment is shaken, loses its strength, and changes to a solid-liquid mixture.
Choose the area that has not experienced a significant earthquake in recorded US history. Wisconsin California Tennessee Alaska South Carolina
Wisconsin
Earthquakes that occur after the main shock of an earthquake are called ________
aftershocks
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 not for another 300 years any day, since it's 200 years overdue
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 tsunami waves surface waves
body waves
Earthquakes are common at plate ______________ because this is where faults are common.
boundaries
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
Even though the Modified Mercalli scale is based on subjective data, it can be useful in measuring ______. long-lasting earthquakes very small earthquakes earthquakes that occur in regions lacking seismographs historical earthquakes
earthquakes that occur in regions lacking seismographs historical earthquakes
Most ______ occur on ______ located at ______. plate boundaries; faults; earthquakes earthquakes; faults; plate boundaries faults; plate boundaries; earthquakes
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
Pieces of lithosphere move past each other along zones of weakness called
faults
The shaking experienced by objects during an earthquake can be measured as an acceleration proportional to the force of ___________ ; any vertical acceleration greater than 1 g would actually cause an object to be lifted in the air.
gravity
The time necessary to build up enough stress to break a fault is called the recurrence ______________
interval
Earthquakes in eastern North America are ______ in the west, and ______. just as frequent as; are related to the subduction zone on the east coast less common than; their energy moves more readily through less fractured rock more common than; they are a lot deeper in focus
less common than; their energy moves more readily through less fractured rock
The ______________of an earthquake measures the amount of energy released, and the subsequent amount of shaking that occurs.
magnitude
The amplitude of seismic waves is used to determine the ___________of an earthquake.
magnitude
What is the one-word term used to describe Earth's very largest earthquakes?
megathrust
The convergent plate boundary off the Pacific Northwest coast is a ______________zone in which the Juan de Fuca plate is diving underneath the North American plate.
subduction
The difference in arrival time between P and S waves is used to calculate ______ an earthquake.
the distance from a seismic station to
How much vertical movement occurs on a fault during an earthquake (excepting megathrust earthquakes)? 5 meters or less 15-25 meters 5-15 meters
5 meters or less
Megathrust earthquakes on the Cascadia subduction zone occur, on average, every ______. 5,000 years 500 years 50 years
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. A seismograph was the original device used to measure earthquakes, and a seismogram is the modern device. They are both devices that record earthquakes.
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
What is a fault? A scar on the land surface where no vegetation grows A vertical crack in Earth's crust A plume of mantle material A zone of weakness in the lithosphere along which movement occurs
A zone of weakness in the lithosphere along which movement occurs
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 Compress the material they travel through Are the highest-velocity waves Travel 3 to 4 kilometers per second in the crust Can travel only through solids
Also known as P waves Compress the material they travel through Are the highest-velocity waves
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 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 plate_________ .
Blank 1: shallow Blank 2: boundaries
Why is a seismic gap an area of concern for future earthquakes along a fault? It is a place that experiences earthquakes on a regular basis (e.g., at least one or two per year). It is a place that has not experienced earthquakes for long periods of time. It is a place that has never experienced an earthquake.
It is a place that has not experienced earthquakes for long periods of time.
Which of the following best describes the current understanding of the relationship between ruptured fault length and earthquake magnitude? Large earthquakes may have greater fault slip over shorter lengths. There is no relationship between earthquake magnitude and fault length rupture. Large magnitude earthquake always are related to long fault ruptures.
Large earthquakes may have greater fault slip over shorter lengths.
Which of the following best describes the current understanding of the relationship between ruptured fault length and earthquake magnitude? There is no relationship between earthquake magnitude and fault length rupture. Large earthquakes may have greater fault slip over shorter lengths. Large magnitude earthquake always are related to long fault ruptures.
Large earthquakes may have greater fault slip over shorter lengths.
The release of energy that is an earthquake occurs in Earth's ______ along faults.
Lithosphere
What two tectonic plates are involved in the Cascadia subduction zone? North American California Juan de Fuca Pacific
North American Juan de Fuca
Which magnitude 6.7 earthquake occurred in January 1994 in the Los Angeles area, causing $20 billion in damage?
Northridge
Of the two types of body waves, which is the faster and compresses the material through which it moves?
P
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
_______body waves cannot pass through liquids, and move perpendicular to their direction of travel.
S
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.
The two forms of waves are _________body and surface waves.
Seismic
During the Great Southern California ______________ , people and emergency services prepare and practice what to do during and after an earthquake.
Shakeout
What type of seismic wave is the second to be recorded at a seismic station following an earthquake? Primary Shear Love Body
Shear
Which of the following describe the 1994 Northridge earthquake? The earthquake occurred in the Los Angeles area. Because the earthquake was deep, few people felt the associated shaking. The primary cause of death due to the earthquake was from building collapse. It caused very little damage.
The earthquake occurred in the Los Angeles area. The primary cause of death due to the earthquake was from building collapse.
What is the relationship between earthquake magnitude and frequency? Frequency is inversely related to magnitude. Frequency and magnitude are not related. Frequency is directly related to magnitude
Frequency is inversely related to magnitude.
A seismic _________is a location along a fault along which movement has not occurred in a significant period of time.
Gap
What is the reasoning for the Great Southern California Shakeout? For scientists to practice how to record and interpret earthquake data collected from multiple recording stations For people and emergency services to prepare and practice in order to mitigate the damage done from the inevitable earthquake that will occur For property owners to simulate the shaking of their homes and businesses in order to know how much insurance they should bu
For people and emergency services to prepare and practice in order to mitigate the damage done from the inevitable earthquake that will occur
True or false: Data from a single seismograph can be used to locate an earthquake.
False
The location on the fault where an earthquake occurs is the __________, while the place on the surface directly above this is the _____________
Focus , Epicenter
Which human factors are most directly associated with how many people are killed by earthquakes?
Building codes and public awareness
Which of these should you not use the Mercalli scale to do? Comparing an earthquake in the Aleutian Islands to one near Seattle Determining an earthquake's intensity Describing the damage associated with an earthquake
Comparing an earthquake in the Aleutian Islands to one near Seattle
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
What are aftershocks? Earthquakes that occur on the same fault following the main earthquake T he psychological symptoms felt by people who have experienced an earthquake Seismic waves that move through buildings and cause them to topple over Small earthquakes that precede a large earthquake
Earthquakes that occur on the same fault following the main earthquake
How do ghost forests provide evidence for large earthquakes?
The land the trees are on decreases in elevation, seawater invades this land, and the roots drown in saltwater, killing the trees.
What is the cause of most earthquakes that occur in eastern North America? The Mid-Atlantic Ridge The reactivation of ancient, buried faults A subduction zone A yet to be discovered reason
The reactivation of ancient, buried faults
How are the records from three seismic stations used to determine the location of an earthquake? Individually, they each can be used to determine the location, but there needs to be two others as a backup. The three distances are represented as circles on a map, and where the three intersect is
The three distances are represented as circles on a map, and where the three intersect is the location of the earthquake.
What happens to rocks on both sides of a fault as stresses are building up over time? Nothing happens to them until the fault breaks. They become distorted. They respond brittlely but in very tiny mico-break
They become distorted.
Megathrust earthquakes ______. rarely cause damage occur on very long faults cause shaking that lasts for minutes are the deepest earthquakes
occur on very long faults cause shaking that lasts for minutes
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
Given earthquakes of the same magnitude occur in different locations, the location with ______ will have a higher earthquake intensity. a deeper focus a smaller population poor building codes
poor building codes
The Modified Mercalli scale ______. ranks earthquakes using Roman numerals is logarithmic measures the intensity of earthquakes is based on damage to buildings and human experiences
ranks earthquakes using Roman numerals measures the intensity of earthquakes is based on damage to buildings and human experiences
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. liquefaction vertical motion horizontal motion shaking
vertical motion
It is difficult to compare two earthquakes of the same magnitude using the Modified Mercalli scale when they occur in regions with ______. or without mountains different geologic histories very different population levels
very different population levels
