Earthquakes Chapter 19. Focus vs. Epicenter _________– where the rock breaks and seismic waves begin; can be at deep or shallow depths _________ – point.

Earthquakes

Chapter 19

Focus vs. Epicenter

_________– where the rock breaks and seismic waves begin; can be at deep or shallow depths

_________ – point on the surface directly above the focus; usually what is used to locate the position of an earthquake

Focus

Epicenter

Seismic Waves

_______ (P) Wave – fastest, able to travel through liquids, energy travels in the same direction wave is traveling

________ (S) Wave – slower, not able to travel through liquids, energy travels at right angles to direction wave is traveling

________ (L) Wave – travels along the surface, responsible for most of the quakes damage

Primary

Secondary

Surface

The interior structure of the earth is determined by the pattern of seismic waves. The __________ is liquid so s-waves can not pass through.

outer core

The difference in arrival times between p-waves and s-waves is called __________.

The greater the lag time (shown here as the distance between the two curves) the _________ the distance away from the earthquake.

lag time

greater

To locate the epicenter of an earthquake, a minimum of ____ seismograph stations is needed. The location is where all circles _______.

three

intersect

Faults Vocabulary:

__________ – surface along which rock layers move

__________ – rock layers above the fault plane __________ – rock layers below the fault plane ________ – angle with the surface the fault plane

makes going down into the ground ________ – direction along the surface the fault

plane creates

Fault Plane

Hanging Wall

Footwall

Dip

Strike

Faults

_______ – Hanging wall moves down; formed from tensional forces

_______ – Hanging wall moves up; formed from compressional forces

________ – Hanging wall and Footwall move

horizontally past each other; formed from shear forces

Normal

Reverse

Strike-Slip

Normal Fault

Reverse Fault

Strike-Slip Fault

Folds

__________ – A-shaped or hump-shaped fold with older rock layers in the center; formed from compressional forces

__________ – U-shaped fold with younger rock layers in the center; formed from compressional forces

Anticlines and Synclines usually occur together and can be large or small scale

Anticline

Syncline

Anticlines and Synclines

Other Vocabulary:

____________ – instrument used to measure seismic waves

__________ – difference in arrival times of p- and s-waves

___________ – rates earthquake by magnitude (amount of energy released)

__________________ – rates earthquake by amount and type of damage

______________ – area of great vertical offset along strike of fault

__________ – large ocean wave caused by vertical movement of ocean floor due to an earthquake

seismograph

lag time

Richter scale

modified Mercalli scale

fault scarp

tsunami

Earthquake Review

The fastest seismic wave which can travel through liquids is a ___________.

The Richter scale measures an earthquakes’ ____________.

A U-shaped fold with the rock layers are _________ in the center is a(n) __________.

A _________ fault is formed when the hanging wall moves up due to __________ forces.

P-wave

magnitude

younger syncline

reversecompressional