Earthquakes - The movement of the ground, caused by - The movement of the ground, caused by waves of energy released as rocks move waves of energy released as rocks move along faultsalong faults

Fault – a large fracture in rocks, from Fault – a large fracture in rocks, from several meters to many kilometers long, several meters to many kilometers long, where rocks not only crack but also move where rocks not only crack but also move along either side of the breakalong either side of the break

Types of Stresses; tension, compression, & Types of Stresses; tension, compression, & shearshear

Types of Faults; Normal, Reverse, Types of Faults; Normal, Reverse, Strike-SlipStrike-Slip

1. Normal Fault1. Normal Fault – a pull apart fracture – a pull apart fracture in rocks, where rocks that are above in rocks, where rocks that are above the fault surface drop downward in the fault surface drop downward in relation to rocks that are below the relation to rocks that are below the fault surfacefault surface

2. Reverse Fault – a compression fracture in rocks, where rocks that are above the fault surface are forced up over rocks that are below the fault surface

3. Strike-Slip Fault – a break in rocks where rocks on either side of the fault move past each other, instead of above or below each other

Concept of ‘hanging wall’ and ‘footwall’

Footwall: Rock surface ABOVE the fault

Headwall: Rock surface ABOVE the fault

Earthquakes (cont.)

Slow steady pressure produces foldsSlow steady pressure produces folds

Types of folds;Types of folds;anticlines - upward bulging fold (ant hill)anticlines - upward bulging fold (ant hill)

syncline - downward bulging fold (dip)syncline - downward bulging fold (dip)monocline - rock layers on one side of monocline - rock layers on one side of

a fold a fold are higher than the are higher than the other sideother side

Anticline

Syncline

Monocline

Route 23 fold

• Route 23 fold

• Route 23 fold

Stresses Building Stresses Building MountainsMountains

1.1. Folded Mountains – caused by compressionFolded Mountains – caused by compression

2.2. Fault-Block Mountains – caused by tensionFault-Block Mountains – caused by tension

3.3. Plutonic Mountains – result from vertical force Plutonic Mountains – result from vertical force created by rising magmacreated by rising magma

4.4. Volcanic Mountains – result of magma from Volcanic Mountains – result of magma from convergent boundaries reaching Earth’s convergent boundaries reaching Earth’s surfacesurface

Folded MountainsFolded Mountains

Fault-Block Fault-Block MountainsMountains

Plutonic Mountain Plutonic Mountain – Half Dome– Half Dome

Volcanic Mountain Volcanic Mountain – Mt. Fuji– Mt. Fuji

Earthquake EvidenceEarthquake EvidenceCreep – very slow down-slope movement, Creep – very slow down-slope movement,

~1cm/yr., leads to severe cracks in buildings~1cm/yr., leads to severe cracks in buildings

Slide – rapid down-slope movement of soil, rocks Slide – rapid down-slope movement of soil, rocks & debris& debris

Scarps – cliff created by sudden earth movements Scarps – cliff created by sudden earth movements along a fault, identified by a curved scar in the along a fault, identified by a curved scar in the landscapelandscape

Fissure – a long crack in soil or rock, up to many Fissure – a long crack in soil or rock, up to many kilometers in lengthkilometers in length

Tsunami – an ocean wave caused by Tsunami – an ocean wave caused by earthquakes, may reach over 100ft. In heightearthquakes, may reach over 100ft. In height

ScarScarpp

CreepCreep

LandslideLandslide

FissureFissure

Tsunami created by Tsunami created by 9.0 earthquake on 9.0 earthquake on Dec.26, 2004 off the Dec.26, 2004 off the west coast of Sumatra west coast of Sumatra in the Indian Oceanin the Indian Ocean

Chile QuakeChile Quake

Feb. 27, 2010Feb. 27, 2010

Magnitude 8.8 Magnitude 8.8 Offshore Offshore Maule, ChileMaule, Chile

Resultant Resultant TsunamiTsunami

Earthquake DamageEarthquake DamageDepends on;Depends on;

1. location of earthquake1. location of earthquake

2. type of ground under buildings2. type of ground under buildings

3. building design & materials3. building design & materials

4. closeness to coastline in case of tsunami4. closeness to coastline in case of tsunami

The EndThe End

Extra Credit

Find and read a news article on Earthquakes - write a three paragraph essay about the article (at least-5 sentences per paragraph). Please include the article.

Sneak it to me no later than the day of the Earthquake test for credit