 Identify causes of earthquakes  Distinguish between S waves, P waves, and surface waves  Describe how earthquakes are measured and rated  Triangulate to find the location of an earthquake  Discuss the types of damage that can occur

 Earthquakes are vibrations caused by movement of rocks sliding past each other.

 These movements of rocks are more common at plate boundaries  California and Japan have many earthquakes because they are on plate boundaries.

RankDateLocationMagnitudeEstimated Deaths/Damages (USD) 11960Chile9.51,655/$6 million 21964Alaska9.2128/$300 million 32004W. Sumatra ,898/estimated in the billions 41952Russia9.1none reported/$1 million 51906Ecuador /unknown 61965Alaska8.7none reported/$10, N. Sumatra /unknown 81950Tibet8.6780/$25 million 91957Alaska8.6none reported/$5 million S. Sumatra8.521/unknown

 In terms of magnitude it won’t be in the top 10 Magnitude 7.0  In terms of destruction and loss of life it will  Already 80,000 buried in mass graves  The number dead may reach over 200,000

Let’s take a look around Port-Au-Prince

 Since the earth’s surface is in motion, rocks in the lithosphere sometimes slip past each other  Well maybe slip isn’t a good word for this, maybe they GRIND past each other  This Grinding caused shock waves that move through the earth

They can move sideways They can move up and down They can push up a section They can not break the surface

The forces build up until the fault breaks – releasing energy

 The focus is where the earthquake occurs  The fault is the plane that the earth slides along  The epicenter is the point on the surface above the focus – it might not be on the fault

 It looks like the needle is moving, but the earth moves under the needle

 Not all earthquakes are the same  At magnitude 6, the ground moves 1 meter at the focus  At magnitude 7, the ground moves 10 meters

 Primary waves  Secondary waves  Surface waves

 Called Primary or Longitudinal waves  Compress and release  Travel fastest  Can travel through earth’s  core but do bend (refract)

 Secondary or Transverse waves  Move up and down (S shaped)  Do not travel through earth’s core

 Rolling up/down or right/left  Occur on surface – like ocean waves  Are the most destructive

 And bounce off different layers of rock

 Found by looking at time between P waves and S waves reaching the seismograph  Calculations tell you the distance to the focus  It takes three seismographic measurements to triangulate where the earthquake is located

 the web site is VQuakeExecute.html

 Buildings collapse Haiti  Roads break up 1989 Loma Prieta Earthquake, San Fransisco  Land can rise or sink 1964 Alaska, some land rose 40 feet, some seafloor dropped 50 feet  Liquefaction Softer rock does not stay together, landfill is some of the worst land to build on  Landslides 1692 the town of Port Royal, Jamaica slide into the ocean, it landed 50 feet below sea level  Tsunamis December 26, 2004 Earthquake

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The farther away you are, the longer it takes for the tsunami to reach you, you have more time to react

 Shows debris lines on the coastline after the 2004 tsunami

 Identify causes of earthquakes  Distinguish between S waves, P waves, and surface waves  Describe how earthquakes are measured and rated  Locate and earthquake by triangulation  Discuss the types of damage that can occur