Chapter 19

All seimometers include a... that is anchored to the ground and vibrates during an earthquake.

A frame

Richer Scale

A numerical scale used to describe an earthquake.

Focus

An earthquake is the point of failure of rocks at the depth where an earthquake originates.

Epicenter

An earthquake is the point on Earths surface directly above the focus.

Fault Scarps

Area of great vertical offset where the faults intercepts the ground surface.

Stress- strain

Curve usually has two segments: a straight segment and a curve sediment.

San Andrea

Famous California strike-slip fault.

Normal Faults

Fracture caused by horizontal tension.

Strike-slip Faults

Fractures caused by horizontal shear.

Reverse Faults

Fractures that forms as a results pf horizontal compression.

Richter Scale

Ia a numerical scale based on the size of the largest seismic waves generated by a quake that is used to describe its magnitude.

The modified- Metallica scale measure an earthquake.

Intensity Decrease

Tsunami

Is a large ocean wave generated by vertical motions of the seafloor during an earthquake.

Shear

Is stress that caused a materials to twist.

Compression

Is stress that decreased the volume of a materials.

Tension

Is stress that pulls a materials apart.

Strain

Is the deformation of materials on response to stress.

Stress

Is the forces per unit area acting on a material.

Faults

Is the fracture or system along which movement occurs, Along which the movement takes places called the fault plane.

Magnutude

Is the measurement of the amount energy released during an earthquake.

P-S determines

It determines the epicenter distance, or distance to the earthquakes epicenter from the seismic station that recorded the waves.

Primary Waves

P- Waves, squeezes and pull rocks in the same direction along with the waves are traveling.

The majority of the worlds earthquakes occurs in?

Relatively narrow seismic belts that are associated with tectonic plates.

Secondary Waves

S-waves, caused rocks to move at the right angles in relation to the direction of the waves.

Magnitude

The amount if energy released by an earthquake is measured by....

Seismology

The study of earthquakes

Seismogram

Us the record produced by a seismometer.

Ductile Deformation

When stress exceeds a cretin value, a material undergoes ductile deformation, shown by that curve sediment of the graph.

Fractures form

When stress exceeds the strength of the rocks involved.

Modified Mercalli scale

Which measure the amount of damage done to the structure involves, is used to determine the intensity of an earthquake.

Moment magnitude scale

Widely by seismologist to measure earthquakes magnitude, takes into account the size of the fault tuner, the amount of movement along the fault, and the rocks stiffness.

seismic gaps

are section of active faults that have experience significant earthquakes for a long period of time.

Seismometers

are sensitive instruments that detect and record the vibration sent put by earthquakes.

Probability of an earthquake

the history of earthquake in an area. The rate at which strain builds up in the rocks.

Surface waves

travel along the Earth surface, moving in two direction as they pass through rocks.