Earthquakes FINAL

True or False: A fault is older than the rocks/sediments it cuts through.

False

True or False: Both public and private schools are required to retrofit unreinforced masonry buildings through the Field Act, Garrison Act, and Greene Act.

False

True or False: If there are enough Magnitude 3 earthquakes, it can greatly reduce the magnitude of a future big earthquake.

False

True or False: If you are alive and not seriously injured after a single tsunami wave hits, it is safe for you to return to lower ground.

False

True or False: If you are on a boat directly over the epicenter of an earthquake that causes a tsunami, you will feel the large waves produced.

False

True or False: In the case of an explosion, the first recorded motion will be upwards only North of the explosion and downwards South of the explosion.

False

True or False: The magnitude of an earthquake is subjective. It can have multiple values to one specific earthquake.

False

True or False: When lava initially (not cooled) enters the Earth's surface it is already aligned with Earth's magnetic field

False

True or False: The San Andreas fault system is a left-lateral system.

False.

Can you have a dip of more than 90°?

No

Choose all phenomena that are accurate to predict all earthquakes: - Ground uplift and tilt - None of them. - All of them. - Radon gas - Seismic velocity variation - Seismic swarms - Animal behavior

None of them.

Which fault is common in a divergent boundary?

Normal

which type of fault is caused by an extensional tectonic environment

Normal fault (ex. subsidence and basin formation)

To first order, what properties of a medium affect seismic wave velocity?

Temperature and density

What is an oblique slip?

right-lateral strike-slip fault + compression

What does the s in S waves stand for?

secondary- sound arrival shear side-to-side particle motion (transverse)

What are the 3 types of faults?

1. Normal Fault 2. Reverse Fault 3. Strike-slip Fault

rank the waves from fastest to slowest - Rayleigh waves - S waves - p waves - love haves

- P waves - s waves - love waves - Rayleigh waves

Why is predicting earthquakes so hard? (select all that applies) - State of stress on fault is very heterogenous. - Basic observations are really hard to obtain. - Earthquake rupture is a critical failure process. - Fault patches are failing all the time and it is difficult to tell if it will become a big rupture.

- State of stress on fault is very heterogenous. - Basic observations are really hard to obtain. - Earthquake rupture is a critical failure process. - Fault patches are failing all the time and it is difficult to tell if it will become a big rupture.

Select all of the countries that have active earthquake early warning systems: - Indonesia - Nepal - United States - New Zealand - Japan - Mexico

- United States - Japan - Mexico

Which of the following are causes of tsunamis? (Select all that apply) - shallow earthquakes - spontaneous landslides - asteroids - volcanic eruptions - strong lunar tides (i.e. the gravitational pull - the moon has on the ocean) - deep earthquakes

- shallow earthquakes - spontaneous landslides - asteroids - volcanic eruptions

What are the three unknowns that seismologists are trying to first characterize during each earthquake?

1. Longitude of the epicenter 2. Latitude of the epicenter 3. Origin time

Why are there different estimates for the mean recurrence interval of (average time between) large earthquakes along the Hayward Fault? Choose all that apply.

1. Some motion along the fault is due to creep, which must be accounted for when considering stream offsets. 2. There is uncertainty in when exactly the historic earthquakes occurred. 3. The number of previous earthquake intervals used for the calculation affects the calculated mean.

What factors control shaking intensity at a site?

1. magnitude of quake 2. Closest distance of the site to the fault rupture 3. Ground condition at the site: rock vs soil vs landfill

What is the proportion of earthquakes that are foreshocks in California? - 1/10 - 1/2 - 1/100 - 1/20 - Foreschocks are fake news. - They are all foreschock.

1/20

What fraction of the motion along the San Andreas fault system is accommodated by the Hayward Fault?

1/5

How many plates are there?

14

How many seismometers exist in California as of this year? - 50 - 200 - 150 - 250

150

What was the magnitude of the earthquake centered in Piedmont, CA on 9/11/22?

2.9

How many seconds of warning would San Francisco have received if earthquake early warning was implemented during the 1989 Loma Prieta earthquake? - 5 seconds - 20 seconds - 10 seconds - 30 seconds

20 seconds

If the total rupture length of the M9 Sumatra earthquake was about 1,300 km, what was the approximate rupture duration?

500 seconds

The approximate time period of the oldest recorded earthquakes?

780 BC

What was the depth of the earthquake centered in Piedmont, CA on 9/11/22?

9.3 km

what percentage of the earths behavior can be explained by one misfracture? - 60% - 84% - 15% - 95%

95%

How much smaller would the amplitude be if the earthquake was 1 mag unit smaller? (controlling the S-P TIME)

A factor of 10

what do beach ball diagrams represent?

A focal mechanism, or "beachball", is a graphic symbol that indicates the type of slip that occurs during an earthquake: strike-slip, normal, thrust (reverse), or some combination. It also shows the orientation of the fault that slipped.

Why are seismologists interested in the possibility of the two faults being connected together? - A longer continuous fault line increases the maximum magnitude earthquake that could be produced. - There is no relevance to hazard, it is purely for academic interest. - Having a longer fault defuses the tension and tends to decrease the magnitude of an earthquake. - Seismologists actually don't study if faults are connected together.

A longer continuous fault line increases the maximum magnitude earthquake that could be produced.

What is a possible source for the Yellowstone supervolcano?

A mantle plume that is coming from the lower mantle, possibly rooted at the core mantle boundary.

By how much does the Earth surface move because of tidal forces? - About 30 cm - Between 2-4 cm - Earth tides only happen for the oceans. - Around a 1m, although they are much - stronger in the oceans

About 30 cm

What is a good indicator of the length of the fault that ruptured?

Aftershocks

Which of the following statements is true? - All earthquakes rupture some piece of a fault. They have a duration time and a length scale in space. - Earthquakes can occur as much as 1000 km deep in the earth. - Earthquakes occur at a singular point in space and time. - Aftershocks just randomly occur and can not give us any clues about the total size of the ruptured fault.

All earthquakes rupture some piece of a fault. They have a duration time and a length scale in space.

Where can transform plate boundaries be found?

Along mid-ocean ridges (ex. Fracture zone e.g South Pacific ) across continent (ex. San Andreas Fault)

Why is the earthquake probability on the South segment of the San Andreas Fault lower than on other faults of the Bay Area? - Because we have less data to estimate the hazard there. - Because of the 1989 Loma Prieta earthquake. - Because the fault there is creeping. - Because the fault there is less active.

Because of the 1989 Loma Prieta earthquake.

What are the two main classes of seismic waves?

Body and Surface waves

What type of seismic waves travel through the "body" of the Earth (travel through the earth's interior)?

Body waves

Which of the following statements is false? - Magnitude is based on instrumental measurements with seismometers. - Both earthquake intensity and magnitude are on a scale of 1 to 10, so they should always have a similar value no matter where you are. - The value of Intensity should vary by locations whereas there an earthquake will only have one magnitude value. - Intensity describes what people experienced and the damage that the earthquake did to infrastructure and buildings.

Both earthquake intensity and magnitude are on a scale of 1 to 10, so they should always have a similar value no matter where you are.

What is the answer to saving lives during earthquakes? - Federal Laws - Earthquake Prediction - Building Codes - Earthquake Early Warning

Building Codes

Which type of plate boundary causes subduction and magma seepage creating volcanos along the plate boundary?

Convergent

Which type of plate boundary allows for the creation of new crust?

Divergent

1. Stress build up due as tectonic plates move together 2. Friction along the fault prevents slip, elastic deformation instead 3. Stress exceeds fault strength, fault slips... earthquake What theory are these steps?

Elastic Rebound Theory

What measures the permanent deformation of an earthquake?

GPS station

What are supporting pieces of evidence for the concept of plate tectonics?

Hotspot Tracks, Magnetic Stripes, and Bathymetry

How does the probability of an earthquake occurring evolve with time, in between two different earthquakes? - It increases. - The probability does not change with time. - It decreases.

It increases.

What do red features on seismic tomography maps typically show?

It is an indication that seismic waves travel slower than average in this region.

Which of the following is not true about earthquake forcasting in 1988? - M6.0 Parkfield did not happen in the forcasted time range. - It strengthed scientists' confidence of precisely forcasting earthquakes. - M6.7 Northridge did happen in 1994 beyond expectation. - It helped scientists to revise their theories and gather precious data in seismology.

It strengthed scientists' confidence of precisely forcasting earthquakes.

What are the two parameters we can determine about an earthquake from the P-wave? - Intensity and time to shaking - Location and Magnitude - Location and Intensity - Magnitude and time to shaking

Location and Magnitude

What type of surface wave has a side-to-side particle motion in horizontal plane?

Love wave

What magnitude earthquake would cause soft-story buildings to collapse? - Magnitude 8 or larger - Magnitude 4 or larger - Magnitude 9 or larger - Magnitude 6 or larger

Magnitude 6 or larger

What is the easiest way to roughly locate an earthquake, if we have access to three different seismometers?

Measure the difference of arrival time between the P and S wave at three different locations.

which type of fault is caused by compressional tectonic environment?

Reverse Fault (ex. shortening and mountain building)

Choose the answer in which the fault types are paired with their correct tectonic environments. - Normal—compressional; reverse—extensional; strike-slip—translational - Normal—extensional; reverse—translational; strike-slip—compressional - Normal—translational; reverse—extensional; strike-slip—compressional - Normal—extensional; reverse—compressional; strike-slip—translational

Normal—extensional; reverse—compressional; strike-slip—translational

What are the two main Large plates that interact in the Bay Area?

North American Pacific

What are the types of body waves?

P waves and S waves

Which ocean had an earthquake early warning system in place at the time of the 2004 Sumatra Earthquake? - Indian Ocean - Pacific Ocean

Pacific Ocean

What measures how the surface of the Earth is moving, including sudden displacement in the earthquake?

Permanent GPS station

What evidence was used to conclude that there was a gigantic earthquake in the Pacific Northwest 300 years ago?

Preserved old tree stumps on the beach, Sudden land subsidence, Tsunami record in Japan, Cascadia volcanoes, and Ring of Fire

What type of surface wave has a circular particle motion in vertical plane?

Rayleigh wave

What are the types of surface waves?

Rayleigh wave and Love wave

which fault is common in a convergent boundary?

Reverse

What measure the motion of an earthquake, either acceleration or velocity?

Seismic station

Which type of wave carries energy away from source?

Seismic wave

Which of the following statements is true about seismic waves? - Seismic waves' speed decreases with higher temperature. - Seismic waves' speed decreases with lower temperature. - Seismic waves cannot travel through objects denser than water. - Seismic waves travel only in the shallow subsurface.

Seismic waves' speed decreases with higher temperature.

In the Loma Prieta earthquake, what type of ground material caused the biggest amplification in Oakland? - Bedrock - Soft mud - Sand and gravel

Soft mud

which type of fault is caused by translational tectonic environment?

Strike-slip fault (ex. San Andrea's/ Hayward Fault)

which seismic wave travels through the earth's surface?

Surface waves

Which one of these statements is true? - The North Anatolian and San Andreas faults have a similar size and character. - Based on the historical record, Istanbul (or Constantinople) has never experienced a big earthquake. - On the North Anatolian fault, an earthquake on one segment cannot cause the next segment to fail. - We can precisely predict when an earthquake will occur in Istanbul.

The North Anatolian and San Andreas faults have a similar size and character.

Even though Mexico City is far away from the subduction zone that runs along the country's west coast, why does it still sustain major damage during earthquakes? - Tsunamis from the earthquakes create the damage, not the seismic waves - The city is built on a lake bed that can amplify seismic waves - The city is built on a bowl of jello that can amplify seismic waves - Damaging seismic waves can travel really far, so it's not actually a surprise

The city is built on a lake bed that can amplify seismic waves

What does it mean for an earthquake to be induced? - The earthquake causes extra vibrations - Human activity caused the magnitude of the earthquake to be exagerated - The earthquake doesn't happen on a fault - The earthquake was man made/caused by humans

The earthquake was man made/caused by humans

How does wastewater injection cause earthquakes? - The fluid injected into the ground opens up the fault plane, allowing slip to occur (resistance to slip is decreased) - The wastewater injection fractures the rock, creating an earthquake - The salt in the wastewater caused a chemical reaction that creates explosions underground

The fluid injected into the ground opens up the fault plane, allowing slip to occur (resistance to slip is decreased)

How can geomorphology help to reveal the slip where there are no obvious creepings?

The offset of river channels can show the faults' movement.

Which of the following statements is false? - The slip models that estimate the amount of slip on the fault plane should have the exact same pattern no matter if we use GPS observation or seismic data. - GPS stations measure the permanent deformation of an earthquake while seismic stations measure the motion of an earthquake, either acceleration or velocity. So they are very different observations. - Permanent GPS stations measure how the surface of the Earth is moving, including sudden displacement in the earthquake. - If an earthquake is big enough, that we could actually observe the rupture processes on both GPS stations and seismic stations.

The slip models that estimate the amount of slip on the fault plane should have the exact same pattern no matter if we use GPS observation or seismic data.

What is a feature the tomography of Western US show at depth?

The subduction zone and the Juan de Fuca slab.

If motion along the Hayward Fault is primarily strike-slip, why do the Berkeley Hills exist?

There is some oblique slip on the fault, and the slight compression causes uplift.

What did engineers change on the oil pipeline in Alaska, where it crosses the Denali fault, in order to reduce the chances of leakage when an earthquake occurs? - They buried it under the ground - They put the pipeline on gliders to let the stiff pipe move side to side. - They put it on stilts. - They made the pipeline out of more flexible material so it can bend.

They put the pipeline on gliders to let the stiff pipe move side to side.

What are the 3 main types of plate boundaries?

Transform Convergent Divergent

True or False: According to the concept of Plate Tectonics, the deformations only occur at plate boundaries.

True

True or False: Contrary to the belief in the 1950s, the theory of Plate Tectonics says that earthquakes will reoccur along fault lines.

True

True or False: Stress builds up continuously along a fault.

True

True or False: The intensity of an earthquake is subjective. It can have multiple values to one specific earthquake.

True

True or False: You will feel stronger shaking at the top of a tall building than if you were on a lower floor.

True

Based on turbidite (underwater landslide) records, we know that earthquakes occur in the Pacific Northwest area. What of the following statements about turbidites is true? - When scientists extracted a drill core, all the layers got mixed together, making it very difficult to recognize individual turbidite records. - Turbidite drill core records show that the recurrence interval of earthquakes in the Pacific Northwest is periodic (meaning earthquakes occur at regular intervals), which means we can easily predict the magnitude, location, and date for a future earthquake. - Turbidite records show that up to 1,000 kilometers of fault length could fail if the entire margin ruptured in an earthquake at once. - Turbidite currents caused by earthquakes can only travel very short distances on the seafloor.

Turbidite records show that up to 1,000 kilometers of fault length could fail if the entire margin ruptured in an earthquake at once.

According to the Modified Mercalli Intensity (MMI) Scale, what is the proper MMI intensity in the comic?Description: many of the cabinet door are swung open and the object are falling out. The many and women are frightened and attempting to run out the house. The plaster is cracked and separating form the wall. Heavy furniture still in place.

VI

Why is it good that most single family homes in California are wood framed? - Wood framed buildings have cripple walls, which help absorb shaking - Wood is good at dealing with vertical shaking (like unreinforced concrete) - Wood and nails have give, so they can absorb some of the energy of shaking - Wood framed buildings are actually not safe, and should be replaced with brick buildings

Wood and nails have give, so they can absorb some of the energy of shaking

What factors control shaking intensity at a site? - The magnitude of the earthquake - Ground condition at the site - All of them - The distance of the site to the fault rupture

all of them

True or False: Since historic earthquakes in Parkfield have occurred at regular intervals, scientists were able to make a correct, precise prediction about when the next earthquake would occur.

false

The velocity of seismic waves...

increases with depth

Is the Hayward Fault near Oakland mostly creeping or locked?

locked

What is the elastic rebound theory?

locked until next earthquake

which surface wave travels faster?

love waves travel faster than Rayleigh

What is seismic moment? - how long the earthquake lasted - the violence of the earthquake shaking - a measurement based on the amplitude of the body and surface waves - measure of energy released by the earthquake

measure of energy released by the earthquake

What is the resolution of the Global Positioning System (GPS) receivers used by scientists to measure fault creep?

millimeters

what is the preferred magnitude scale today?

moment magnitude scale, abbreviated Mw

Before the Parkfield earthquake in 2004 occurred, which precursory signal did scientists observe?

no precursory signals were observed

which body wave travels faster?

p waves travel faster the S waves

Fill in blank: seismic moment is a ____________ quantity

physical

What is a locked surface movement?

plate tectonic strain accumulating for an earthquake

What is a creeping surface movement?

plate tectonic strain released by slow creep

What does the p in P waves stand for?

primary- first arriving push-pull particle motion

Fill in blank: earth is _____________ symmetric

radially

What are some causes of man made earthquakes? (Select all that apply) - reservoir filling - oceanic plate subducting under continental plate - traffic on freeways - collapsed mine - wastewater injection

reservoir filling collapsed mine wastewater injection

Which fault is common in a transform boundary?

strike-slip

What is the epicenter?

the "point" at which the earthquake occurs

what is the dip angle?

the angle between a vertical line down the face of the surface and horizontal

what is an earthquake?

the release of built-up stress along faults

Why is it more difficult to determine whether an earthquake is natural or man made in California than in Oklahoma and Northern Texas? - there is more oil extraction in Oklahoma and Northern Texas than in California - there is a lot more natural seismicity in California than there is in Oklahoma and Northern Texas - there is no regular time interval for earthquakes in California - earthquakes occur more frequently in Oklahoma and Northern Texas

there is a lot more natural seismicity in California than there is in Oklahoma and Northern Texas

what is a turbidite?

underwater landslide

_________ is long term, injects large volumes of fluid, and causes many felt earthquakes. ________ is short term, injects small volumes of fluid, and cause few felt earthquakes. - hydraulic fracturing - wastewater injection

wastewater injection is long term, injects large volumes of fluid, and causes many felt earthquakes. hydraulic fracturing is short term, injects small volumes of fluid, and cause few felt earthquakes.