Earthquakes and Deformation of the Crust 1. 2 Deformation of the Crust Stress –Force that causes...

Earthquakes and Deformation of the Crust

1

Earthquakes and Deformation of the Crust

Earthquakes and Deformation of the Crust

2

Deformation of the Crust

• Stress –Force that causes pressure in the

rocks of the earth’s crust

 • Strain

–Change in the shape or volume of rocks from stress

Earthquakes and Deformation of the Crust

3

Rock Layers Experience

shearing compression

tension

Earthquakes and Deformation of the Crust

4

Folding

• When rock becomes permanently deformed without breaking–Anticline–Syncline–Monocline

Earthquakes and Deformation of the Crust

5

Anticline• When rock layers are folded

and uplifted into arch like patterns

Earthquakes and Deformation of the Crust

6

Syncline• Downward folds like a

bowl

• Or sink

Earthquakes and Deformation of the Crust

7

Monocline• Gently dipping fold in the rock

layers

Earthquakes and Deformation of the Crust

8

Faulting   • Fault

–Break in rock

–Rocks on either side of the break move

• Fracture–Break in rock with no movement.

Earthquakes and Deformation of the Crust

9

Folds Vs. Faults

Earthquakes and Deformation of the Crust

10

Footwall & Hanging Wall

Earthquakes and Deformation of the Crust

11

Normal Fault • Fault plane is 45° or more• Hanging wall drops relative to the

footwall• Divergent boundaries

Earthquakes and Deformation of the Crust

12

Reverse Fault

• Hanging wall moves up relative to the footwall

• Due to compression

Fault plane is 45°

Earthquakes and Deformation of the Crust

13

Thrust Fault

• Special kind of reverse fault

• Fault angle is less than 45°

Earthquakes and Deformation of the Crust

14

Strike Slip

Earthquakes and Deformation of the Crust

15

Reverse Normal

Thrust Blind Thrust

Strike Slip

Oblique

Earthquakes and Deformation of the Crust

16

Mountain Formation

• Smallest to Biggest–Mountain

–Mountain range

–Mountain system

–Mountain belt

Earthquakes and Deformation of the Crust

17

Mountain Belts

• Evidence that mountains are created when lithospheric plates collide

• Name some examples• Appalachians?

–Formed where plates collided in the past 

Earthquakes and Deformation of the Crust

18

Folded Mountains

• Formed when tectonic movements have squeezed the rock layers together like an accordion

Earthquakes and Deformation of the Crust

19

Earthquakes and Deformation of the Crust

20

Fault Block Mountain

• Formed when faulting breaks the Earth’s crust into large sections

• The sections are uplifted and tilted

Earthquakes and Deformation of the Crust

21

Earthquakes and Deformation of the Crust

22

Fault Block Mountain and Graben

Earthquakes and Deformation of the Crust

23

Grabens• long narrow valley formed by

faulting and downward slippage of a crustal block

Earthquakes and Deformation of the Crust

24

Volcanic Mountains

• Formed when molten rock erupts onto the earth’s surface

•  

Earthquakes and Deformation of the Crust

25

Dome mountains

• Created when molten rock pushes up rock layers on the Earth’s surface

• Then the layers then are worn away in places, leaving separate high peaks.

Earthquakes and Deformation of the Crust

26

Earthquakes and Deformation of the Crust

27

Earthquake

• vibration of the Earth

• produced by the rapid release of energy

Earthquakes and Deformation of the Crust

28

• Elastic Rebound Theory explains the cause of earthquakes.

Earthquakes and Deformation of the Crust

29

Elastic Rebound Theory

Earthquakes and Deformation of the Crust

30

Elastic Rebound Theory• Rocks are moving slowly on

either side of a fault• if the fault is locked in place,

stress in the rocks increases• Rocks that are strained past a

certain point will fracture, move, and spring back to their original shape

Earthquakes and Deformation of the Crust

31

Locked

• When friction prevents the rocks on either side of a fault from sliding past each other

Earthquakes and Deformation of the Crust

34

• Most earthquakes occur along or near the edges of the earth’s – lithospheric plates

• Fault Zone– group of interconnected faults

Earthquakes and Deformation of the Crust

35

San Andreas Fault Zone• has formed where the edge of the

Pacific plate is slipping north along the North American plate

Earthquakes and Deformation of the Crust

36

San Andreas Fault zone

Earthquakes and Deformation of the Crust

37

Aftershocks

• tremor that follows a major earthquake

• is smaller

• Caused or related to the major earthquake

Earthquakes and Deformation of the Crust

38

Focus

• zone along a fault where slippage first occurs

• produces an earthquake

• 0rigin of the quake

Earthquakes and Deformation of the Crust

39

Epicenter

• point on the Earth’s directly above the focus of an earthquake

• May or may not be the point of greatest shaking, most damage

Earthquakes and Deformation of the Crust

40

Focus and Epicenter

Earthquakes and Deformation of the Crust

42

Seismograph

• instrument for recording seismic waves

Earthquakes and Deformation of the Crust

43

Seismograph

Earthquakes and Deformation of the Crust

44

Seismograph

Earthquakes and Deformation of the Crust

45

Modern Day Seismograph

Earthquakes and Deformation of the Crust

46

Richter Scale•Measure of the magnitude of a quake, or energy released

•31.7 times more energy is released for every whole number

• 3.1 to 5.1?• 31.7 x 31.7 = approx. 1000

Earthquakes and Deformation of the Crust

48

Seismic Waves

Earthquakes and Deformation of the Crust

49

P waves S waves

L waves

Speed Fastest Middle Slowest

Amp-litude

Smallest Middle Largest

Period Shortest Middle Longest

Medium

Solid, gas, liquid

Solids On the Surface

Earthquakes and Deformation of the Crust

50

Earth Quake Location

Earthquakes and Deformation of the Crust

51

Earth Quake Location

Earthquakes and Deformation of the Crust

52

Earth Quake Location