Dynamics of the Earth

I. Evidence of Crustal Motions:

A. ________________ wears down the earth’s crust.____________ _______________ creates new mountains.

Weathering & Erosion

( Uplift )Plate tectonics

B. Sedimentary beds are

deposited as_______________

__(_____ _)

Horizontal Layers

Strata

THIS SEDIMENTARY STRATA SHOWS NO EVIDENCE OF UPLIFT OR CRUSTAL MOTION LAW OF

ORIGINAL HORIZONTALITY

C. Evidence of motions within

the Earth’s crust is indicated by:1._____________2._____________3._____________

TiltingFoldingFaulting

TILTING

FOLDING

FAULTING: OFF SET LAYERS

FAULTING

D. ______________provide direct

evidence of crustal movement.

Earthquakes

World Distribution

U.S . Distribution

_______ ______ and________ _______

are 2 changes thatcan be observed after

an earthquake.

Fault lines Uplifted land (displaced strata)

EARTHQUAKE DAMAGE

E. ______ ________are used in mapping surveys and indicate exact positions and

elevations.

Bench marks

Changes in ________________

of benchmarks are evidence that the

land is either ___________

or____________risingsinking

elevation

F.Displaced marine fossils found in mountains have 2

interpretations:

1. ____________________________________________________________

2. _____________________________________________________________

Higher sea levels covered mountains

Rocks were upliftedfrom a previous ocean bottom

G. _____________is the rising of the crust_____________

is the sinking of the crust

Uplift

Subsidence

II: EARTHQUAKES

1. The movement of ____________ inside

_______________

2. _______________ is the movement of rock along a surface where the rocks are broken.

A. 2 processes that cause earthquakes:

magma

volcanoes

faulting

B. ________ movement of the crust over long periods of time builds ___________

within the rocks.

Slow

stress

Increased pressure causes the _______ _______

to break creating a ________.

Rock strata

fault

When faulting occurs energy radiates through the earth as ________ ________ that cause the ground to_______________

Seismic waves

vibrate

III.Measuring the Earthquakes:

A. There are 2 scales to measure earthquakes:

1. ________________

2. ________________

Mercalli

Richter

B. _______________ scale is based upon the observations of people and damage caused. It

measures ___________ of the earthquake from____ to ____

Mercalli

intensity

1 12

Mercalli Scale – Intensity scale

I

II

III

IV

V

VI

C._______________

uses the seismograph to determine the ________________

Magnitude is the total______ released by the earthquake.

Richter Scale

magnitude

energy

Its numerical scale is ____ to ____.

Each of the numerical steps represent ____ increase.

1 10

31X

Richter Scale – Magnitude scale

V. Parts of the Earthquake:

A. The place underground where the break or fault occurs is the _______ of the quake.

focus

The __________ is the location along the surface of the earth just above the focus where the earthquake is felt most strongly.

epicenter

A. The 2 most important energy waves are:

P-wave or Primaryand

S-wave or Secondary

P-wave

Primary Wave

S-wave

Secondary wave

B. Characteristics of Primary Waves (P)

waves: _______________________ _______________________

_______________________ _______________________

Faster than S wavesRecorded first

travels through both solids and fluids

C. Characteristics of Secondary Waves (S)

waves: _______________________ _______________________

_______________________

_______________________

Slower than P wavesRecorded after P-wave

Can not travel

through fluids

TYPES OF EARTHQUAKE WAVES

D. Both S and P

waves travel faster through ___________

material.denser

VI. Finding the Epicenter:

A. The seismograph records the ________________ and

________________________________________

magnitude

Records arrival time of seismic waves

Use reference table page 11

Seismograph

B. The steps for calculating your distance from the

epicenter:

1. ________________________2. ________________________

3. ________________________

4. ________________________

Subtract arrival time of P from arrival time of S

Mark the interval on Y-axis

Slide marks to match P & S curve

Follow down to x-axisand read distance

01:10:00 01:20:0001:18:00 01:24:00

Step 1 Subtract the arrival time

of the P wave from the

arrival time of the S wave

01:24:00 - 01:18:00 00:06:00Lag time= 6 minutes !!!

Step 2

Mark the interval on the Y-axis

Step 3Slide the marks to

match the P and S Curves.Make sure the

paper is straight!

Step 4Follow down to the X-axis

and read distance

Practice questions:

1. The arrival of the P-wave is 12:03:00.

The arrival of an S-wave is 12:07:00 the difference is:

How far is this earthquake from the seismic station? 4 minutes

2600 Km

Practice questions:2. The arrival time of the

P-wave is 2:05:00The arrival of the S-wave is 2:08:00

the difference is:How far is this earthquake from the seismic station?

3 minutes

1800 Km

Practice questions:

3. If the difference in arrival time between P and S waves is 2 minutes 35 secondswhat is the distance from the earthquake to the

Seismograph stations?1500 Km

Practice questions:

4. How long does it take for a P-wave to travel from the focus of an earthquake to a seismograph station 2,000 km. away?

4 minutes

Practice questions:5. What is the difference in

arrival time between P and S waves for an earthquake

that is 5,000 kilometer away from a seismograph station?

6 mins 40 secs

VII. THE ORIGIN TIME OF AN EARTHQUAKE:

A. Earthquake waves detected at _______ times by observers are at _______ distances from the epicenter.

later

greater

B. To find the origin time seismologists need to

know:1. _____________________

2. _____________________

Arrival time of P-wave

Travel time of P-wave(how long it took)

Example:

A seismograph recording station located 5,700 km. from an epicenter.

It receives a P-wave at 2:45pmAt what time did the earthquake actually occur at the epicenter?

First:use the distance to find outthe travel time.Then: subtract the travel time from the arrival time.

The answer is:

9 min.

2:36

SF = San Francisco 300 km

LV = Las Vegas 390 km

LA = Los Angeles 189 km

Seismic Stations

TRIANGULATION TO FIND THE EPICENTER

SF

LVLA

300 km

VIII. THE LAYERS OF THE EARTH:

A. The crusts thickness______ It is _________________ under the oceans and

_________ under continents.

varies

thinner

thicker

Continental crust is mostly_______________, ____________density & __________________

The ocean basins are mostly ________ and ______ or ___________

granitic

dark densebasaltic

lowlight

B. Inferred characteristics of Earth’s

Interior:1. Studying the _____________

of _____________ ________ allows us to make inferences about the structure and composition of the Earth’s interior.

transmission

EarthQuake Waves

S-waves can not pass through liquid

P-waves are bent as they passthrough the different layers

Based on the density of the layer

2. The _____________ of a seismic wave changes with the __________ of the material it travels through.

Waves are also ___________ (bent) as they travel through different densities

velocity

density

refracted

We know that P-waves can be transmitted through

________ _______ & ______

S-Waves can be transmitted through ONLY

________________

solid liquid gas

solid

3. Earth Quake Shadow Zones:When an earthquake occurs both

____________ are received from most of the earth.

Opposite sides of the earth where the epicenter is, receives

____ but NO _______ because S-waves can not penetrate the _______ outer core.

S and P waves

SP

liquid

S-waves can not pass through liquid

____________ occurs at the ___________ (boundaries)

refraction interfaces

Let’s Draw This Diagram in our Notebook: