Earthquakes- Midterm Study Guide

if the total rupture length of the M9 Sumatra earthquake was about 1,3000 km, what was the approximate rupture duration?

500 seconds

In seismic tomography, seismic stations are used to measured seismic waves and determine their velocities. Match the general wave velocity to its corresponding temperature.

fast velocity --> cold temperature

slow velocity --> hot temperature

What kind of earthquake mechanism is this? (the one that looks like a pizza cut into quarters)

strike-slip

Which number region in this tomographic image identifies a subducted tectonic plate? (two are places marked in red, one is marked in blue, and one is just the pacific plate)

the one marked in blue

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

This diagram shows earthquakes occurring almost sequentially from east to west along the North Anatolian Fault. What can be said, generally, about this fault?

An earthquake on one segment of the fault makes the adjacent segment more likely to fail/ experience an earthquake

What do you need in order to calculate the slip-rate along a fault that offsets a stream channel?

the length of the offset and the age of the stream channel

Why is the Hayward Fault one of the most hazardous faults in California? (Select all that apply)

so many people live and work on or near the Hayward Fault

there is a high chance of a big earthquake on the Hayward Fault in the next 30 years

What kind of fault is the San Andreas fault?

right-lateral strike-slip fault

Please match the plate boundaries with the correct descriptions.

mid-ocean ridges -->

subduction zones -->

transform zones -->

mid-ocean ridges --> new oceanic plates

subduction zones --> oceanic plate destruction

transform zones --> no plate creation or destruction

The Haywired Scenario is:

one possible version of how a M7.0 earthquake could play out on the Hayward Fault

Match the beach ball diagram to its tectonic environment/ earthquake type:

-pizza cut into fourths -->

-the one with the white in the middle -->

-the one with the black in the middle -->

-the black circle -->

-pizza cut into fourths --> strike-slip

-the one with the white in the middle --> normal

-the one with the black in the middle --> reverse (thrust)

-the black circle --> explosion

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?

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

For what purpose was the first global seismic network built?

Detecting nuclear tests

Which of the following is a body wave that is second to show up on seismograph and is defined by shear motion?

S-waves

Look at this image of an apartment building after the 2014 M6.0 Napa Earthquake. Use the provided Mercalli scale to assign an intensity to what you see. Enter a number (like 3) instead of a Roman numeral (like III) in the answer box. Since there is a subjective element to determining intensity, you will receive credit for answers that are +/- 1 level of the correct value. (in the picture, like some of the front of the building had damage, but it hadn't collapsed or anything)

6

Do actual tall buildings in countries like Japan and the US really sway during large earthquakes?

Yes, buildings do sway a few feet from side to side

Movies about earthquakes often show huge cracks opening in the earth. In reality:

it is possible for small cracks to open as the energy of an earthquake rolls through, but not people-swallowing sized

What was the name of the report written after the 1906 San Francisco earthquake?

The Lawson Report

In Japanese mythology, what mythical creature was believed to cause earthquakes?

A giant catfish called Namazu

What kinds of observations can be explained by plate tectonics (multiple answers)?

-global distribution of earthquakes

-Bathymetry of ridges and trenches

-Magnetic stripes on the ocean floor

What's a method for determining the age of a tectonic plate?

Observing polarity reversal of magnetic stripes on the ocean floor

How are earthquakes distributed globally?

Close to plate boundaries

When should you turn off your gas after an earthquake?

turn off gas when you smell gas after an earthquake

What should you do if you are inside during an earthquake? (pick 2)

-stay inside until shaking has stopped

-drop, cover, hold on

What causes the majority of injuries during an earthquake?

Objects that break or fall on people

What are faults?

fractures in the Earth's crust where there is movement along the fracture.

What are earthquakes?

a release of built up stress on a fault

Which of the following is created by tensile and lengthening forces and creates basins.

normal faults

Which of the following is created by compressive and shortening forces and creates mountains?

reverse faults

Which of the following is caused by translational forces and creates movement in the strike direction?

strike-slip faults

What are some examples of convection?

-The movement of material in the Earth's mantle

-Movement in a lava lake

-Movement in a bowl of hot miso soup

What was the largest earthquake in recorded history?

The 1960 Chile earthquake

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

-tsunami record in Japan

-sudden land subsidence

-preserved old tree stumps on the beach

Have there been big earthquakes on the Hayward Fault?

yes

Why is the curb in Hayward not aligned?

the motion on the Hayward Fault is causing the surface to move

The CDC suggests (Links to an external site.) that refrigerators can be useful in protecting things, including medication, from fire.

true

What is the most significant and commonly cited reason to wear shoes after a major earthquake?

Because one of the most common injuries is stepping on sharp debris like broken glass

What might you need gloves for?

-sturdy work gloves protect hands while handling debris

-surgical gloves can protect the injured from infection and protect the responder from pathogens

-keep hands warm in cold temperatures

When considering how much water you might need, what is one thing you do not need to plan to use your personal water supply for?

firefighting

Why are scissors a recommended part of a first aid kit?

for cutting through clothes and trimming bandage lengths

Why are familiar foods recommended for e-kits over things like 'meals ready to eat' (MREs) or nutrition replacements like Soylent?

in the midst of so much stress, unappetizing food is even less likely to sit well in your stomach

Select all the document types a person might, depending on their situation, want to have in their emergency kit:

-social security card

-a will or trust document

-financial obligation documentation, like bills and mortgages, including contact information

-documentation for prescriptions

-citizenship or visa documents

-titles to any cars or houses owned

-lease agreements for rented homes

-pet microchip numbers

-health and property insurance documentation, including your policy number(s)

-copies of ID documents, such as drivers licenses, passports, and birth certificate

-bank account numbers

-adoption, marriage, and/or divorce papers

For what safety reason might you want a picture of family / household members in your e-kit?

in case someone goes missing or gets separated from the group

Why is it a good idea to have up-to-date pictures of your belongings (especially valuables) and the condition of your home stored in the cloud or in a safe location?

so that you can file a financially accurate insurance claim if you sustain property damage

What is the reason it is recommended to have a whistle in a go-bag?

to signal for help if you are trapped

Why do you need a flashlight?

in case the power goes out

Why do you need a fire extinguisher in the event of a major emergency?

to put out small household fires, especially since it is unlikely Emergency Services will be able to reach you in time

Why should you have blankets and warm clothes in an e-kit even if you live in a hot place?

to keep people who are in shock warm

About every 100-220 years, there will be a large earthquake that occurs on the Hayward fault. When was the last big one?

1868

In the next 30 years, what's the chance of an M6.7 or larger earthquake occurring on the Hayward Fault or Rodgers Creek Fault?

1 in 3

What potential hazards could accompany a large earthquake?

-aftershocks

-liquefaction

-landslides

-fire

What is UC Berkeley doing?

taking managable, incremental steps to improve seismic building safety on campus

Why couldn't engineers find the Hayward fault under the Foothills residential halls?

Previous landslides had covered the fault

Choose the true statement:

-Earthquakes can occur as much as 1000 km deep in the earth.

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

-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.

Which of the following is a type of body wave that is the first to show up on a seismograph, is defined by push and pull motion, and is felt vertically.

p-wave

Which of the following is a body wave that is second to show up on seismograph, is defined by shear motion, and is felt horizontally?

s-wave

Which of the following is a surface wave that has circular motion in the vertical plane?

Rayleigh wave

Which of the following is a surface wave that has side-to-side particle motion in the horizontal plane?

love wave

Match the waves to the order that they are felt.

-p-waves

-s-waves

-rayleigh and love waves

in the order in which they're listed...

Which of these best describes the definition of magnitude?

The amount of energy released by an earthquake

Which of these best describes intensity?

The strength of earthquake shaking in a particular location

"Instruments across California recorded varying durations of the strongest shaking emanating from Ridgecrest.

A device at the Naval Air Weapons Station China Lake (Links to an external site.), about a mile away from the ruptured fault, showed it lasted for a relatively short period, [USGS seismologist Robert] Graves said — perhaps 15 to 20 seconds.

But that was on bedrock, said USGS seismologist Susan Hough. Shaking energy that feeds into softer sediments can increase the felt at the surface and [cause the shaking to] last dramatically longer."

Intensity

Below is a quote from the Anchorage Daily News about the 2018 M7 earthquake in Alaska. Is the quantity of energy inferred from the earthquake's magnitude or intensity?

[The] earthquake just north of Anchorage on Friday morning shredded the earth with 2 million tons of explosive force, and generated 650 aftershocks within 30 hours, some of them large enough to rattle residents all over again, experts say.

magnitude

Below is an image of 2 possible earthquake scenarios on the Hayward Fault as generated by the Haywired Scenario. The white region in the center of each panel corresponds to the area of the fault that could rupture (i.e. slip) in an earthquake. Do the colored regions represent magnitude or shaking intensity?

intensity

Read the following description of energy released by the 2004 Northern Sumatra Earthquake from the USGS website. Is what they are describing related to the magnitude or the intensity?

The 2004 Sumatra earthquake released an estimated "20 × 10 17Joules, or 475,000 kilotons (475 megatons) of TNT, or the equivalent of 23,000 Nagasaki bombs [worth of energy]."

magnitude

What's the deepest we've ever drilled into the Earth?

12 km deep

True or false: S-waves can travel through the liquid outer core

false

What factors control shaking intensity at a site?

-ground condition at the site

-the distance of the site to the fault rupture

-the magnitude of the earthquake

Choose the false statement.

-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.

-Magnitude is based on instrumental measurements with seismometers.

-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.

The 2004 Sumatra tsunami still holds the record for the greatest number of fatalities from a tsunami in recorded history.

true

Tsunami require vertical displacement of the seafloor to occur.

true

A tsunami is created in a subduction zone because the edge of the overriding tectonic plate, which has been _______ as it gets dragged by the subducting plate, suddenly _______.

dragged under; snaps back up

Damaging tsunamis are preceded by a significant recession of water from the shore.

true

All earthquakes that happen underwater produce a tsunami.

false

The first tsunami wave is always the most destructive.

false

Which statement is true?

Tsunami waves are more like a thick wall of water than a regular wave

What is a tectonic plate?

A block of lithosphere

The lithosphere consists of:

the crust and the upper mantle

The tectonic plates can be ____ at plate boundaries

created, consumed, or nothing can happen

This plate boundary is (the picture shows two rectangular prisms with arrows going towards one another):

convergent

The type of fault associated with convergent plate boundaries is:

reverse/thrust

This plate boundary is (the picture shows two rectangular prisms with arrows going away from one another):

divergent

A divergent plate boundary is associated with what kind of faulting?

normal

What is this type of boundary (it shows two rectangular prisms with arrows making them go past one another)?

transform

The type of faulting associated with transform boundaries is?

strike-slip

Seafloor spreading occurs when two plates

are moving away from each other

True or false: Rocks found along divergent boundaries are youngest away from the plate boundary

false--rocks are younger closer to the boundary

What type of land feature is created when two continental plates move away from each other?

rift valleys

What land feature is created when continental & continental collide?

mountains

What kind of plate boundary is shown in the picture (the picture shows two plates moving past one another)?

transform

What type of plate boundary creates the island of Japan?

oceanic oceanic colliding

What type of plate boundary is shown (the picture shows the South American plate going towards the Nazca Plate)?

convergent- oceanic continental

What type of tectonic feature is shown in the picture (the picture shows the South American plate and the African plate creating a rift in the ocean between them)?

Atlantic seafloor spreading

Land features such as island arcs, trenches, volcanoes, earthquakes occur...

Along plate boundaries

What type of boundary is shown (they show one plate subducting under another)?

convergent

When ocean and continental plates collide, which plate subducts beneath the other?

oceanic because it's more dense

Which process produces new crust?

-seafloor spreading

-subduction

-karst topography

-shearing

seafloor spreading

Which process consumes crust?

-seafloor spreading

-subduction

-karst topography

-shearing

subduction

Most of earth's volcanos are formed from

meeting or separating of plates