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EaRtHqUaKeS!!!

What do earthquakes feel like?San Francisco Earthquake of 1989Seismology: the study of earthquakesMost earthquakes take place near the edges of tectonic plates (most active earthquakes occur along the plates surrounding the Pacific Ocean)

What else is The Ring of Fire known for?What Causes Earthquakes?As tectonic plates push, pull or scrape against each other, stress builds up along faults until the rocks finally move

A fault is a break in the Earths crust where plates slide, push or pull against each other

What Causes Earthquakes?Deformation is the change in the shape of rock in response to stress.Rock can deform in 2 ways:- plastic- elastic***Write this in your glossary!***Plastic DeformationStress causes the crust on one side of a fault bend like clay

THIS DOES NOT LEAD to EARTHQUAKES!!!! Elastic DeformationRock can only stretch so far before it will break

Like a rubber band, when it breaks, energy is released and the broken pieces return to their unstretched shape causing energy to spread through the earth in waves.

THIS DOES LEAD to EARTHQUAKES!!!!

Are All Earthquakes the Same?No. Depending on the type of plate boundary, earthquakes can be strong or weak.Plate MotionEarthquake CharacteristicsTransformModerate, shallowConvergentStrong, deepDivergentWeak, shallow***Copy this chart in your notebook!***How Do Earthquakes Differ?Not all earthquakes are the same.The type of earthquake that occurs depends on the type of plate motion and fault type there is!

***Write down the part in red***Transform = Strike-SlipIf two plates have a transform motion, they will probably have a strike-slip fault between them

A strike-slip fault is when two blocks of crust slide past each other horizontally

These types of earthquakes are moderate and shallow

***Write the definition of strike slip in your glossary***Convergent = ReverseIf two plates have a convergent motion, they will probably have a reverse fault between them.

A reverse fault happens when two blocks of crust are pushed up against each other and they slide vertically.

These types of earthquakes are usually strong and deep.

***Write the definition of in your glossary***Divergent = NormalIf two plates have a divergent motion, they will probably have a normal fault between them

A normal fault occurs when two blocks of crust are pulled away from each other and slide vertically

This type of earthquake is usually weak and shallow

***Write the definition of in your glossary***Earth on the MoveEarthquake WavesAll earthquakes release energy called seismic waves

Scientists measure seismic waves to determine the scale (how big or small) an earthquake is

Most people use the Richter scale to measure earthquake seismic waves

How Seismographs Work

http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTMthe pendulum remains fixed as the ground moves beneath itTypical Seismogram

http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt How Are Earthquakes Measured?This is a seismographIt is an instrument located at or near the surface of the Earth that records seismic waves

What Scale is Used to Measure the Strength of an Earthquake?The Richter Scale

MagnitudeEstimated Effects2Can only be detected by a seismograph3Can be felt at the epicenter*4Felt by most in the area5Causes damage at the epicenter6Causes widespread damage7Causes great, widespread damage* Right where the earthquake beginsHow are Earthquakes Measured? Richter Scale

Primary Waves (P Waves)A type of seismic wave that compresses and expands the ground. Primary waves are longitudinal waves. They can travel through liquids.

The first wave to arrive at an earthquake. P comes before S in the alphabet.

http://daphne.meccahosting.com/~a0000e89/insideearth2.htm***Write the definition in your glossary***Secondary Waves (S Waves)A type of seismic wave that moves the ground up and down or side to side. These are transverse waves. They cannot go through liquids. They are the second wave people feel. They are sometimes called the aftershock.

http://daphne.meccahosting.com/~a0000e89/insideearth2.htm***Write the definition in your glossary***Comparing Seismic Waves

Surface WavesMove along the Earths surfaceProduces motion in the upper crustMotion can be up and downMotion can be aroundMotion can be back and forthTravel more slowly than S and P wavesMore destructive***Write the definition in your glossary***

How do scientists calculate how far a location is from the epicenter of an earthquake? Scientists calculate the difference between arrival times of the P waves and S waves

The further away an earthquake is, the greater the time between the arrival of the P waves and the S wavesScientists used what we know about S and P waves to figure out the layers of the Earth.

What information may have helped them to determine which parts of the Earth are solid and which are liquid?

Locating Earthquakes

http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTMLocating Earthquakes

http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTMLocating Earthquakes

http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTMFocus point inside the Earth where an earthquake beginsEpicenter point on Earths surface above focus