Earthquake Damages ERS exam 3

What type of motion characterizes P-waves?

Compression waves

Which type of earthquake wave has a high frequency and is considered the least damaging?

P-waves

What type of motion characterizes S-waves?

Shearing waves 

Which type of earthquake wave is described as having high frequency and being destructive?

S-waves 

Which type of earthquake wave has a low frequency and causes the most ground motion?

Surface waves

Which category of earthquake waves is considered the most destructive?

Surface waves

In which type of geologic material are earthquake waves amplified?

Loose sediments

What is the term for the process where saturated soil substantially loses strength in response to stress, like an earthquake, and behaves like a liquid?

Liquefaction

What is the term for the compaction of geologic fill material as a result of an earthquake?

Consolidation/compaction

The 1985 earthquake in _____ is a key example of wave amplification in loose sediments

Mexico City

What is a primary design goal for earthquake-resistant buildings regarding their movement?

To move as a single unit and be decoupled from the ground, like a shock absorber

Which building materials are generally associated with more damage in an earthquake compared to steel or wood?

Concrete and masonry

What is resonance in the context of earthquake damage to buildings?

The phenomenon where the frequency of seismic waves matches a building’s 'natural period' of vibration, amplifying the motion

Which two types of seismic waves cause the most damage to building structures?

Surface waves and S-waves

What is one factor that influences earthquake damage risk related to the location of the event?

Distance from the fault

What is one factor that influences earthquake damage risk related to infrastructure?

Distance from utilities

Name one of the secondary effects that can be caused by earthquakes

Landslides, fires, or tsunamis

The 1906 San Francisco earthquake is a notable example of extensive damage caused by what secondary effect?

Fires

The Richter scale is a _____ scale

logarithmic

What does the Richter scale measure to determine an earthquake's magnitude?

The amplitude of the largest seismic wave recorded

What is the basis for the Modified Mercalli Intensity Scale?

It is based on human observation of the earthquake's effects

List two factors that can cause the intensity on the Modified Mercalli scale to vary from place to place for a single earthquake

Distance from the earthquake, earthquake strength, geologic materials, or building construction

What does the Moment Magnitude Scale measure?

The total energy released by an earthquake

The Moment Magnitude scale is a function of what three properties?

Rock rigidity, distance of slip, and the rupture surface area

How does the Moment Magnitude scale relate to the Richter scale?

The calculated energy is scaled to be consistent with the Richter scale

The New Madrid earthquakes of 1811-1812 occurred in which region of the USA?

Central USA

How were the sizes of the New Madrid earthquakes estimated, given the lack of nearby instrumentation?

Estimates were based on sparse eyewitness accounts, to which the Modified Mercalli Scale was applied

What geological phenomenon during the New Madrid earthquakes was described as 'tidal waves'?

This likely refers to large waves on the Mississippi River or liquefaction effects, not a true tsunami

The New Madrid earthquakes of 1811-1812 caused the Mississippi River to temporarily _____

Reverse its flow

What is the maximum warning time currently available from short-term earthquake warning systems?

Seconds to minutes

How do modern early warning systems work?

They use high-tech sensors (accelerometers) to detect the arrival of the initial P-wave, providing a warning before the more damaging S-waves and surface waves arrive

The 2017 Prueba Earthquake in Mexico had an early warning time of ____

Less than a minute

What is the term for a long-term assessment of earthquake probability in a given area?

Earthquake forecasting (or assessing seismic risk)

Term: Small earthquakes that often precede a major earthquake

Foreshocks

Term: A segment of an active fault known to produce significant earthquakes that has not slipped in an unusually long time compared with other segments

Seismic gap

Changes in the emission of what gas have been observed before some earthquakes, though their predictive value is uncertain?

Radon

What are the three scales mentioned in the source material for measuring earthquakes?

The Richter Scale, the Modified Mercalli Intensity Scale, and the Moment Magnitude Scale

What key factors influence the damage caused by an earthquake wave?

Earthquake strength, geologic materials, building design, and distance from the fault are primary factors

Where do most earthquakes on Earth occur?

At plate boundaries

What is the general nature of earthquake activity in Maine?

Weak earthquakes occur periodically, and the threat from a 'big' earthquake is small

If two earthquakes of equal energy occur at the same epicenter, why would one at 5 km depth cause more damage than one at 10 km depth?

The shallower earthquake (5 km) is closer to the surface, resulting in stronger ground shaking and more structural damage

To minimize risk of injury during an earthquake, which building material is generally safer: wood or unreinforced masonry/concrete?

Wood structures are generally less susceptible to damage than unreinforced concrete or masonry

On the Richter scale, how much larger is the seismic wave amplitude of a magnitude 5 earthquake compared to a magnitude 3?

100 times the seismic wave amplitude (10 times for each whole number increase)