Earthquakes February 2013

Earthquakes occur when plates move can happen at any plate boundaries or fault lines Earthquakes

Steps to an EQ 1. Stress forces rock to begin moving

2. Rock undergoes Elastic Deformation (bends/buckles) Steps to an EQ

Steps to an EQ 3. Rock Cracks

4. Elastic Rebound: stressed rocks bounce back to undeformed shape Steps to an EQ

http://earthquake. usgs. gov/learn/animations/animation. php http://earthquake.usgs.gov/learn/animations/animation.php?flash_title=Elastic+Rebound&flash_file=elasticrebound&flash_width=300&flash_height=350

3 Types of Earthquake Waves

P-waves pressure or primary waves first waves compress the rock

S-waves shear or secondary waves second wave in a quake move rock side to side

Surface waves roll rock like water wave most destructive happen in the most severe quakes

http://sunshine.chpc.utah.edu/labs/seismic/index.htm

Start Points Epicenter: point on surface above where quake occurs Focus: point underground where quake began

Earthquake Words Seismology: study of earthquakes Seismologist: person who studies quakes Seismograph: instrument used to record quakes Seismogram: reading from seismograph Seismos: means “to shake”

Measuring Earthquakes Richter Scale- Numbers 1-10 each interval increases strength by 10 times Mercalli Scale - uses Roman numerals I-XII to record intensity and damage (damage differs based on structures in area) Highest quake recorded-9.5 in Chile in 1960; number two 9.2 in Alaska

Earthquakes since the beginning of 2012