Earthquakes - The movement of the ground, caused by waves of energy released as rocks move along faults Fault – a large fracture in rocks, from several meters to many kilometers long, where rocks not only crack but also move along either side of the break Types of Stresses; tension, compression, & shear Types of Faults; Normal, Reverse, Strike-Slip Types of Faults; Normal, Reverse, Strike-Slip

1. Normal Fault – a pull apart fracture in rocks, where rocks that are above the fault surface drop downward in relation to rocks that are below the fault 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 folds Types of folds; anticlines - upward bulging fold (ant hill) syncline - downward bulging fold (dip) monocline - rock layers on one side of a fold are higher than the other side

Anticline Syncline Monocline

Route 23 fold

Stresses Building Mountains 1.Folded Mountains – caused by compression 2.Fault-Block Mountains – caused by tension 3.Plutonic Mountains – result from vertical force created by rising magma 4.Volcanic Mountains – result of magma from convergent boundaries reaching Earth’s surface

Folded Mountains Fault-Block Mountains

Plutonic Mountain – Half Dome Volcanic Mountain – Mt. Fuji

Earthquake Evidence Creep – very slow down-slope movement, ~1cm/yr., leads to severe cracks in buildings Slide – rapid down-slope movement of soil, rocks & debris Scarps – cliff created by sudden earth movements along a fault, identified by a curved scar in the landscape Fissure – a long crack in soil or rock, up to many kilometers in length Tsunami – an ocean wave caused by earthquakes, may reach over 100ft. In height

Scarp Creep Landslide

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

Chile Quake Feb. 27, 2010 Magnitude 8.8 Offshore Maule, Chile Resultant  Tsunami

Earthquake Damage Depends on; 1. location of earthquake 2. type of ground under buildings 3. building design & materials 4. closeness to coastline in case of tsunami

The 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