2. Real- Time Earthquake Data http://earthquake.usgs.gov/

3. EQ = Movement of E’s lithosphere that occurs when rocks in the lithosphere suddenly shift, releasing stored energy. EQs occur b/c stress forces of have exceeded the strength of rock. Stress builds when rocks along 2 sides of a fault snag and lock (friction) as stress builds – so does POTENTIAL ENERGY IN ROCKS When rocks are strained beyond limit – they break & move. (Potential  Kinetic Energy in form of seismic waves) EQs

4. Stress & Strain on Rocks Stress – Force that squeezes rocks together, pulls them apart, pushes in diff. directions. Stress causes strain or deformation (change in shape or volume) of rock Stress FoldsFaults Does not exceed rock strength Exceeds rock strength

5. Stress Folds = Bending rock layers Faults = Breaks in rock layers & movement along breaks Does not exceed rock strength Exceeds rock strength High Temps. & Pressure Low Temp. & Pressure – Near Crust

6. Folds Anticline = up facing fold Syncline = down ward facing fold

7. Faults

8. Types of Faults http://www.windows.ucar.edu/tour/link=/earth/geology/fault.html 1. Dip – Slip Motion up or down fault surface

9. Types of Faults 2. Strike – slip Sliding – Horizontal Movement 3. Oblique – slip dip-slip & strike slip combined

10. Interpretation of Tectonic History DivergentTransform Plate Boundary: Convergent NormalThrust/ReverseStrike-Slip

11. EQ vibrations begin at a point called a FOCUS. Vibrations travel from focus through the earth’s crust as waves. Surface directly above the focus is called the epicenter. These waves can be detected and measured on earth’s surface with a SEISMOGRAPH. EQ Vibrations

12. Instrument that measures & records EQ waves. Strength of EQ waves is referred to as MAGNITUDE. SEISMOGRAPHS Wave Motion: http://sunshine.chpc.utah.edu/labs/seismic/index.htm?ASPIRE_Session =964f1ed30b7e49ceb81bd77f444d9230 http://sunshine.chpc.utah.edu/labs/seismic/index.htm?ASPIRE_Session =964f1ed30b7e49ceb81bd77f444d9230

13. 3 Types of Seismic Waves 1. Primary Waves (P waves) 2. Secondary Waves (S waves) 3.Surface Waves Each wave originates from the FOCUS of the earthquake. Each wave travels in a different way, at different speeds, and causes different amounts of destruction.

14. Seismic Waves = vibrations produced by energy released during EQ Virtual EQs http://www.sciencecourseware.org/VirtualEarthquake/VQuakeExecute.htmlhttp://www.sciencecourseware.org/VirtualEarthquake/VQuakeExecute.html Seismic Waves http://www.geo.mtu.edu/UPSeis/waves.html http://www.geo.mtu.edu/UPSeis/waves.html P Waves: Primary Wave Arrives 1 st & Travels FASTER. Compress & Expand like accordion (like sound waves) Move through Solids & Liquids Least destructive

15. Seismic Waves S Waves – Secondary What you FEEL in an EQ Rock moves up & down or side to side (Snake-like) Arrive after P Move only through SOLIDS

17. Seismic Waves: Surface Waves Surface Waves develop when vibrations reach surface Slowest waves Most destructive, most damaging More P & S wave animations: http://www-rohan.sdsu.edu/~rmellors/lab8/l8maineq.htmhttp://www-rohan.sdsu.edu/~rmellors/lab8/l8maineq.htm Video clip: http://news.bbc.co.uk/1/hi/sci/tech/4126809.stmhttp://news.bbc.co.uk/1/hi/sci/tech/4126809.stm

18. Rating Earthquakes Earthquakes are rated in terms of MAGNITUDE or INTENSITY by different scales. 1.Moment Magnitude Scale 2.Richter Scale 3.Mercalli Scale

19. Uses a seismogram Rates on scale from 1- 10 Looks at Eqs in terms of ENERGY Each # releases 31 times more ENERGY than the # before it. Example A 6 releases 31 times more energy than a 5, and a 5 releases 31 times more energy than a 4. The energy difference between a 4 and a 6 EQ is 31 X 31 = 961 Moment Magnitude Scale

20. Uses a seismogram Rates on scale from 1- 10 Looks at Eqs in terms of the SIZE OF THE WAVES Each # has waves 10x bigger than previous # 1 – 3: Small earthquake waves – very little shaking 4 – 6: Moderate earthquakes – noticeable shaking and some damage 7 - 10+ BIG Earthquakes – Very destructive Richter Scale

21. Mercali Intensity Scale Measures observed RESULTS or DAMAGE of Earthquake on a 1 – 12 scale Degree of shaking and DAMAGE to structures Don’t need a seismogram Link http://www.abag.ca.gov/bayarea/eqmaps/doc/mmi.html

22. Deaths & Injuries Damage to buildings & structures Underground water and gas pipes break – floods & fires Landslides Tsunamis EFFECTS OF EQs

23. Seismic Waves are used to Study Earth’s Interior Link: http://sunshine.chpc.utah.edu/labs/seismic/index.htm?ASPIRE_Sessi on=964f1ed30b7e49ceb81bd77f444d9230 http://sunshine.chpc.utah.edu/labs/seismic/index.htm?ASPIRE_Sessi on=964f1ed30b7e49ceb81bd77f444d9230 P and S waves are “bent” and their velocities are affected as they move through material of varying density

24. Latest Quakes http://earthquake.usgs.gov/eqcenter/recente qsww/Quakes/quakes_all.php Top Ten Lists http://earthquake.usgs.gov/eqcenter/top10.p hp

25. Links Virtual Earthquakes http://www.sciencecourseware.org/VirtualEarthquake/VQuakeExecute. html Wave Types http://www.geo.mtu.edu/UPSeis/waves.htmlhttp://www.geo.mtu.edu/UPSeis/waves.html Triangulation & “Hearing EQs” http://www.seismo.unr.edu/ftp/pub/louie/class/100/seismic-waves.html More virtual seismograms http://www-rohan.sdsu.edu/~rmellors/lab8/l8maineq.htm Earthquakes outline subducting slab – Interactive Web Lab– http://openlearn.open.ac.uk/mod/resource/view.php?id=172185