Homework #2 - Earthquake Physics

In Wikipedia, look up "Epicenter" and answer this question: How can seismograms be used to locate an earthquake?

The time difference between the P wave and S wave arrival times indicated distance

In Wikipedia, look up "Earthquake", read the intro then scroll down to "Earthquake fault types", and answer this question: True or False: Rocks hotter than about 300°C (472°F) flow in response to stress; they do not rupture in earthquakes

True

In Wikipedia, look up "Hypocenter" and answer this question: What is the difference between a hypocenter and an epicenter?

A hypocenter is the location an earthquake initiates at depth, while an epicenter is the location above the hypocenter at the surface

In Wikipedia, look up "Seismogram" and answer this question: What does a single seismogram record?

Ground motion at a measuing station as a function of time

In Wikipedia, look up "Shadow zone" and answer this question: Look at the figure which shows some of the paths that P waves travel from an earthquakes that occurs at 0 degrees though the Earth and explain what causes the P-wave shadow zone (region where no direct P waves are observed)?

P-waves are refracted (their direction is altered) because they slow down when they encounter the liquid outer core

In Wikipedia, look up "List of Earthquakes", read the intro then scroll down to "Largest earthquakes by magnitude", and answer this question: What is the largest earthquake by magntitude to ever be recorded?

The 1960 Valdivia, Chile earthquake

In Wikipedia, look up "San Andreas Fault" and answer this question: The San Andreas Fault is the boundry between which tectonic plates?

The Pacific and North American plates

In Wikipedia, look up "P wave" and answer this question: Which of the following is a propery of P waves?

They are the first signal from an earthquake to arrive at any affected location

In Wikipedia, look up "S wave" and answer this question: Which of the following is a propery of S waves?

They cannot travel through liquids (assume low viscosity)

In Wikipedia, look up "Earthquake", read the intro then scroll down to "Earthquake fault types", and answer this question: Where do strike-slip faults occur?

Where the two sides of the fault slip horizontally past each other, such as at transform boundries

In Wikipedia, look up "Elastic rebound theory" and answer this question: In the content of earthquake, what does elastic-rebound accomplish?

-It allows rocks to deform between earthquakes without breaking -It allows for the release of accumulated energy during an earthquake -It allows the two sides of a fault to move with respect to each other during an earthquake (Answer is all of the above

In Wikipedia, look up "Stick-slip phenomenon" and answer this question: Which of these statements applies to stick-slip behavior?

-It explains the behavior of seismically active faults -Surfaces alternating between sticking to each other and sliding over each other -If an applied force is large enough to overcome the static friction between two surfaces, they will slide relative to each other (Answer is all of the above)

In Wikipedia, look up "Seismic tomography", read the intro then scroll down to the "Applications" and answer this question: Seismic tomography, also known as earthquake seismology, uses earthquake to map the deep interior. Which of the following can be imaged by seismic tomography?

-Subduction zones -High velocity (cold) structures beneath continental shields (thick centers of continents) -Low velocity (warm structures beneath ocean spreading centers

In Wikipedia, look up "Rayleigh wave", read the intro then scroll down to the "Generation from earthquakes" and answer this question: Which of the following is a propery of Rayleigh waves?

-They can travel around the Earth several times before dissipating -They are the slowest moving seismic wave -They tend to cause more damage than P and S waves (Answer is all of the above)

In Wikipedia, look up "Earthquake" and answer this question: Which of the following can earthquakes trigger?

-Tsunami -Landslides -Volcanic eruptions (Answer is all of the above)

In Wikipedia, look up "Earthquakes" and answer this question: Look at the figure showing earthquake epicenters: where do most earthquakes occur?

Along the boundries between tectonic plates

In Wikipedia, look up "Reflection seismology" and answer this question: Reflection seismology images the subsurface (meaning shallow surface). Which of the following is not used in these experiments?

Earthquakes

In Wikipedia, look up "Earthquake", read the intro then scroll down to "Earthquake fault types", and answer this question: Where do normal faults occur?

In areas where the crust is being extended such as a divergent boundry

In Wikipedia, look up "Earthquake", read the intro then scroll down to "Earthquake fault types", and answer this question: Where do reverse faults (also known as thrust faults) occur?

In areas where the crust is being shortened such as at a convergent boundry

In Wikipedia, look up "Seismic magnitude scales" and answer this question: What is the difference between an earthquake magnitude and its intensity?

Magnitude describes the size of an earthquake and intesity describes the severity of shaking