midterm 2 Flashcards
what is the term used for a fracture in a rock on which there has been no appreciable movement?
joint
to be useful as a geochrometer, radioisotope half-lives should be approx
10^9 years
T/F reflected seismic waves bounce off the boundary between two materials with different seismic velocities
True
T/F richter magnitude is linearly related to the seismic energy released in an earthquake
False
on a 1:24,000 scale map, 1 inch on the map is equivalent to what distance at earth’s surface?
24,000
T/f a normal fault can violate the principle of superposition by placing older strata vertically above younger strata
False
what three things should you do in the event of an earthquake?
- drop to the floor
- take cover under a sturdy desk or table
- hold on to a sturdy object to keep it from moving away from you
which factors influence the intensity of shaking felt at earth’s surface during an earthquake?
- near surface ground composition (e.g. bedrock, sediment, artificial fill)
- the distance to a coastline
- the depth to the hypocenter
- the amt of buildings within the shaking zone
- density and age of the underlying bedrock
- near surface ground composition (e.g. bedrock, sediment, artificial fill)
- the depth to the hypocenter
- density and age of the underlying bedrock
T/F deformation is a synonym of metamorphism
False
what is the approx thickness of the lithosphere
100km
T/F an absolute age is measured in years and typically involves a radiometric dating technique
True
T/F radiometric dating of earth materials provides a max constraint on the age of earth’s formation
False
T/F earthquake science has now advanced to the point where we an accurately predict the day and magnitude of a future earthquale
False
What are the SI units of stress
N/m^2
Which scale measures the intensity of ground shaking during an earthquake?
Modified Mercalli scale
What physical quantities do geophysicists use to image earth’s interior
- seismic vel
- magnetic susceptibility
- electrical resistance
- heat flow
- seismic vel
- magnetic susceptibility
- electrical resistance
- heat flow
Explain why P waves travel through a fluid but S waves do not
μ of a fluid is 0
T/F earth would still have a geodynamo and magnetosphere even without a liquid outer core
False
Which of the following are types of radioactivity used in radiometric dating?
- delta particle emission
- isotope fractionation
- alpha particle emission
- spontaneous fission
- alpha particle emission
- spontaneous fission
archimedes principle states that the buoyancy force exerted on a floating object is equal to the weight of the fluid displaced by the object. the application of archimedes principle to earth’s crust is called
isostasy
a(n) ___ is an atom with a variable number of neutrons
isotope
which type of plate boundary experiences megathrust earthquakes?
ocean-continent convergence
the ___ is the geographic point at the earth’s surface directly above the focus of an earthquake
epicenter
which type of seismic waves do the most damage to surface infrastructure during an earthquake
surface waves
