Introduction to Earthquakes

Vocabulary Seismology: the study of earthquakes Seismologist: person who studies earthquakes

What are they? Earthquakes: a shaking of the Earth caused by tectonic plate movement Occur at the surface or deep underground Earthquake zones: places where a lot of faults are located

Where do earthquakes occur? Remember: plates move in different directions and at different speeds They interact at faults

Where do earthquakes occur? Faults- breaks in the Earth’s crust due to sliding tectonic plates 3 types: reverse, normal, strike-slip Some earthquakes occur in faults in the middle of plates, but most occur at edges

Normal Fault Divergent boundary

Reverse Fault Convergent boundary

Strike-Slip Fault Transverse boundary

When plates move, The rocks undergo deformation 2 types: plastic deformation and elastic deformation

Plastic Deformation Rocks bend like a piece of molded clay Does not cause earthquakes

Elastic Deformation Rocks stretch to a point, then break. When they break, they release energy Elastic rebound: when the pieces return to their unstretched shape. Causes earthquakes! http://earthquake.usgs.gov/learn/animations/animation.php?flash_title=Elastic+Rebound+Flash+Animation&flash_file=elasticrebound&flash_width=300&flash_height=350