test 3 Earthquakes and volacanoes

How would you recognize a left-lateral strike-slip fault?

When you straddle the fault, the left-hand side has moved toward you.

Law of original horizontality

Which law of physical geology can be used to determine that these rocks layers were deformed into folds after they were deposited? states that sediments deposited in water form as horizontal layers.

Porous

a porous material holds water

Transform faults are fractures that form in order to _________.

allow spreading centers to wrap around the curved surface of Earth

The decrease in velocity of both P and S waves at about 100 km depth marks the top of the

asthenosphere

Which type of seismic wave is the fastest?

body wave

Seismic waves that pass through the interior of the planet are called _______________ waves, whereas those that travel across the surface are called ____________ waves

body; surface

Reverse faults form in response to which type of stress?

compression

P waves are ______ and can travel through air, just like sound waves do, and hence are audible.

compressional

Dip-slip faults generally form in response to ______ forces.

compressional and tensional

At which type of plate boundary would you be most likely to find reverse dip-slip faults?

convergent

Geologists measure the orientation of tilted rock layers. ______________ is the angle of inclination from the horizontal of a tilted rock layer, and ________ is the compass bearing of a rock layer where it pierces the horizontal plane.

dip ; strike

A dip-slip fault is one where movement is ______________.

dominantly vertical

A(n) ___________ is the vibrations we feel when sudden movement occurs along a fault. (Enter only one word per blank.)

earthquake

An earthquake occurs from the release of ______ when stress on a fault builds high enough for the rocks to snap and move suddenly.

energy

The principal of inertia

explains that a stationary object will remain stationary unless acted upon by an external force

Faults can be recognized in the field, even if the fault plane itself is not exposed, because ______.

faults offset rock units

Veins of valuable ores are common along faults because ______.

fluids containing dissolved metals can more easily flow through fault zones

The number of waves passing a given point during one second is referred to as ______.

frequency

Similar to sound waves passing through a trombone, the shorter the rupture length along a fault, the ______ the frequency of the seismic waves that are generated.

higher

Seismographs like the one shown here record seismic waves because the heavy weight does not move with the framework of the instrument. This is due to the _____ of the weight.

inertia

Fault

is a planar feature where the two sides move past each other

Because of their low frequency and slow speed, surface waves carry _____ amounts of energy away from the epicenter.

large

The location of the epicenter and hypocenter of an earthquake can be determined by ______.

looking at the difference in arrival times of different types of seismic waves

This type of surface wave travels parallel to Earth's surface in a side-to-side motion.

love

The San Andreas fault in California is the most famous example of a _______ fault.

right-lateral strike-slip

Because their motion is up and down and side to side,_________ waves are the type of body wave that can do severe damage to buildings

s

The second type of seismic wave to reach a recording station after an earthquake is a(n) ______________ wave

secondary

Wave frequency and period are related. The higher the frequency, the _________ the period.

smaller

P waves can travel through air, where they take the form of _______________ waves. You might experience this as a sonic boom.

sound

The law of superposition

states that within a sequence of undisturbed sedimentary, the oldest layer is at the bottom

The San Andreas in California and the Alpine in New Zealand are examples of __________ __________ faults.

strike slip

Normal faults form in response to which type of stress?

tension occur mostly on ocean floor

ip-slip faults generally form in response to ______ forces.

tensional compressional

Spreading centers are linked to each other or to subduction zones by __________ faults which allow the rigid lithosphere to move over a curved surface.

transform

The ______ nature of S waves make them apt to damage buildings.

transverse

Love waves are a type of surface wave. They are similar to S waves in that they ____________

travel with a shearing motion at right angles to their direction of advance cannot travel through fluids but can travel through solid material

The velocity of P waves depends on the ______ and _______ of the material through which they pass.

- density - compressability

Which of these correctly describe the nature of surface waves?

- slow moving -low frequency

Which of the following describe a primary (P) wave?

-Can travel through any material -The first to reach a recording station -Moves in a push-pull fashion

Which of the following best describe an S wave?

-Has a shearing motion -The second to reach a recording station -Cannot travel through fluids

S waves can travel through ______

-mudstone -sandstone -granite rock

The Law of original Continuity

-states that sedimentary layers extend laterally until they thin out at their edges -Law tells us that when a sedimentary rock layer abruptly terminates, something must have happened to it after it formed.

P wave velocity depends upon the material through which the wave passes. Rank these materials from the fastest P wave velocity at the top to the slowest at the bottom.

1) Granite rock 2) packed sand 3) loose sand 4) water 5) air

To study earthquakes, seismologists must record the movement of earthquake waves in ______ directions.

3

What is the minimum number of seismograms needed to determine the location of the epicenter of an earthquake?

3

a strike-slip fault

A fault where the slip is predominantly horizontal and parallel to the fault plane

fault

A fracture in bedrock along which sliding has occurred

What happens when the stored potential energy in a fault is suddenly released after building up for many years?

An earthquake occurs.

When a left-lateral strike-slip fault has a right-stepping bend, what kind of topographic feature is likely to form?

An uplifted mound or hill

seism

Another term for an earthquake is a ______

Fracture

If no movement occurs, then the planar feature is called a

Surface waves are referred to as ______ waves because they take more time to complete one cycle of motion and are the slowest moving.

L (long)

If a feature truncated by a strike-slip fault is displaced to the left on the other side of the fault, what type of fault is it?

Left-lateral strike-slip

A _____________ ________ ______ occurs when the hangingwall moves down relative to the footwall

Normal dip-slip fault

The drastic decrease in P wave velocity and the disappearance of S waves at the depth shown with an arrow on this graph marks the top of which layer of the Earth's interior?

Outer Core

If a feature truncated by a strike-slip fault is displaced to the right on the other side of the fault, what type of fault is it?

Right-lateral strike-slip

Strike-slip faults form in response to which type of stress?

Shear

What is the S-P time?

The difference in arrival time of S waves and P waves

seismic waves

The energy released when a fault ruptures radiates outward from the hypocenter as

Why don't the rocks on either side of a fault simply slide past each other when stress is applied?

Friction holds the rocks together

Why do geologists map the location of active faults?

To assess earthquake hazards

Transform faults

First recognized by J. Tuzo Wilson in 1965, ___________ _____________ are a special type of horizontal-movement fault that connects the ends of two offset segments of plate edges.

How do scientists identify the depth to the top of the asthenosphere in the Earth's interior?

Both P and S waves slow down.

At which type of plate boundary would you be most likely to find normal faults?

Divergent

seismometer

The instrument used to detect seismic waves

seismograph

The instrument used to record seismic waves

frequency

The number of waves passing a given point during one second

Why do S waves disappear at the core-mantle boundary?

The outer core is liquid, and S waves cannot travel through a liquid.

Epicenter

The point on the Earth's surface directly above where the fault first ruptures

hypocenter

The point where a fault first ruptures

seismology

The study of earthquakes

The arrival times of which two types of seismic wave are used to calculate the location of an earthquake's epicenter?

p wave and s wave

What characteristic of faults allows water to carry dissolved metals that are precipitated as ores within the fault zone?

permeable

two types of body waves

primary and secondary waves

If, during an earthquake, you feel like you're being rocked in a boat at sea, you are most likely feeling the passage of ____________ waves.

rayleigh

A _______ ______ ________ occurs when the hangingwall moves up relative to the footwall

reverse dip-slip fault