1. EARTHQUAKES…

2. What is an Earthquake? Shaking and vibration at the surface of the earth caused by the underground movement along a FAULT plane. Shaking and vibration at the surface of the earth caused by the underground movement along a FAULT plane. Results from a sudden release of energy in the Earth's crust that creates SEISMIC WAVES. Results from a sudden release of energy in the Earth's crust that creates SEISMIC WAVES. Tectonic plate interaction is the primary cause. Tectonic plate interaction is the primary cause.

3. 1960 Valdivia Chile Earthquake Largest Earthquake ever recorded Largest Earthquake ever recorded Moment Magnitude of 9.5 !!! Moment Magnitude of 9.5 !!!

4. Generated a massive tsunami Generated a massive tsunami 2000 killed – over $550M in damage 2000 killed – over $550M in damage This Building Was Washed in by Tsunami Wave

5. Ocean-Continental Convergence = Nazca Plate subducting beneath S. American Plate

6. 122 Killed in Onagawa, Japan

7. 61 Killed Hilo, Hawaii

8. NAZCA PLATE S. AMERICAN PLATE TRENCH EPICENTER

9. EPICENTER The location on Earth’s surface that lies directly above the forces of an earthquake (The Focus). The location on Earth’s surface that lies directly above the forces of an earthquake (The Focus).

10. FOCUS The zone within Earth where movement along a fault produces an earthquake. The zone within Earth where movement along a fault produces an earthquake.

11. What is a FAULT? A FAULT is a fracture or zone of fractures between two blocks of rock. A FAULT is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. Faults allow the blocks to move relative to each other. Slow movement = “creep” Slow movement = “creep” Rapid Movement = “earthquake” Rapid Movement = “earthquake” Faults may range in length from a few millimeters to thousands of kilometers. Faults may range in length from a few millimeters to thousands of kilometers.

12. 3 Classifications of Faults 1. Normal Faults: Rock above the fault plane has moved DOWN relative to the rock below. (Divergence) Normal Fault Flash Animation Normal Fault Flash Animation Normal Fault Flash Animation Normal Fault Flash Animation 2. Reverse (Thrust) Faults: Rock above the fault plane moves UP relative to the rock below. (Convergence) Thrust Fault Flash Animation Thrust Fault Flash Animation Thrust Fault Flash Animation Thrust Fault Flash Animation 3. Strike-Slip Faults: A fault along which the movement is horizontal. (Transform) Strike-slip Fault Flash Animation Strike-slip Fault Flash Animation

16. Stress = Deformation

17. Sumatra Mega-thrust (Reverse) Fault

19. Tsunami 2004, Dec. 26th http://www.news.cornell.edu/releases/Jan 05/tsunamiVid640.html http://www.news.cornell.edu/releases/Jan 05/tsunamiVid640.html http://www.news.cornell.edu/releases/Jan 05/tsunamiVid640.html http://www.news.cornell.edu/releases/Jan 05/tsunamiVid640.html

20. SUMATRA TSUNAMI 2004

21. Sumatra Tsunami 2004

22. So…. How do Seismologists measure the strength of an EARTHQUAKE? EARTHQUAKE?

23. Giuseppe Mercalli – 1902 Qualitative Data Charles Richter – 1936 Quantitative Data

24. Mercalli Intensity (at epicenter) Witness Observations I Felt by very few people; barely noticeable. II Felt by a few people, especially on upper floors. III Noticeable indoors, especially on upper floors, but may not be recognized as an earthquake. IV Felt by many indoors, few outdoors. May feel like heavy truck passing by. V Felt by almost everyone, some people awakened. Small objects moved. Trees and poles may shake. VI Felt by everyone. Difficult to stand. Some heavy furniture moved, some plaster falls. Chimneys may be slightly damaged. VII Slight to moderate damage in well built, ordinary structures. Considerable damage to poorly built structures. Some walls may fall. VIII Little damage in specially built structures. Considerable damage to ordinary buildings, severe damage to poorly built structures. Some walls collapse. IX Considerable damage to specially built structures, buildings shifted off foundations. Ground cracked noticeably. Wholesale destruction. Landslides. X Most masonry and frame structures and their foundations destroyed. Ground badly cracked. Landslides. Wholesale destruction. XI Total damage. Few, if any, structures standing. Bridges destroyed. Wide cracks in ground. Waves seen on ground. XII Total damage. Waves seen on ground. Objects thrown up into air. Modified Mercalli Scale (Qualitative)

25. Richter Scale is Logarithmic: Each magnitude is 10x stronger than the previous.

26. MOMENT MAGNITUDE Invented in 1977 by Hiroo Kanamori Invented in 1977 by Hiroo Kanamori Moment is a measure of earthquake size that takes into account how much the fault slips and over how much area. Moment is a measure of earthquake size that takes into account how much the fault slips and over how much area. Identical to Richter for EQ’s 7 and smaller. Identical to Richter for EQ’s 7 and smaller. More precise for measuring larger EQ’s. More precise for measuring larger EQ’s.

27. INTENSITY vs. MAGNITUDE The MAGNITUDE of an EQ is how much energy is released during the event. The MAGNITUDE of an EQ is how much energy is released during the event. INTENSITY describes the perceptible moving, shaking and damage experienced during the event. INTENSITY describes the perceptible moving, shaking and damage experienced during the event. Two EQ’s can have same magnitude, but very different intensity depending upon such variables as location relative to the epicenter, type of bedrock and soil in the region, as well as the type of fault where the EQ occurred. Two EQ’s can have same magnitude, but very different intensity depending upon such variables as location relative to the epicenter, type of bedrock and soil in the region, as well as the type of fault where the EQ occurred.

28. How are Earthquakes Recorded? A seismogram is a record written by a seismograph in response to ground motions produced by an earthquake, explosion, or other ground-motion sources A seismogram is a record written by a seismograph in response to ground motions produced by an earthquake, explosion, or other ground-motion sources

29. How do Seismologists use this Data?

30. Seismic Waves 1) Surface Waves: Waves that travel along Earth’s outer layer. Earth’s outer layer. 2) Body Waves: Travel through Earth’s Interior…….2 Kinds P- Waves P- WavesS-Waves *** Identified by how they travel through the materials within the Earth

31. Surface Waves Love Waves Love Waves The first kind of surface wave is called a Love wave, named after A.E.H. Love, a British mathematician who worked out the mathematical model for this kind of wave in 1911. It's the fastest surface wave and moves the ground from side-to-side. The first kind of surface wave is called a Love wave, named after A.E.H. Love, a British mathematician who worked out the mathematical model for this kind of wave in 1911. It's the fastest surface wave and moves the ground from side-to-side.

32. Surface Waves Rayleigh Waves The other kind of surface wave is the Rayleigh wave, named for John William Strutt, Lord Rayleigh, who mathematically predicted the existence of this kind of wave in 1885. A Rayleigh wave rolls along the ground just like a wave rolls across a lake or an ocean. Because it rolls, it moves the ground up and down, and side-to-side in the same direction that the wave is moving. Most of the shaking felt from an earthquake is due to the Rayleigh wave, which can be much larger than the other waves. The other kind of surface wave is the Rayleigh wave, named for John William Strutt, Lord Rayleigh, who mathematically predicted the existence of this kind of wave in 1885. A Rayleigh wave rolls along the ground just like a wave rolls across a lake or an ocean. Because it rolls, it moves the ground up and down, and side-to-side in the same direction that the wave is moving. Most of the shaking felt from an earthquake is due to the Rayleigh wave, which can be much larger than the other waves.

33. P-Waves (Compression)

34. S-Waves (Shear)

35. P-WavesS-Waves Primary Waves Secondary Waves Faster Slower Compression “Push” Wave “Shear” Waves Direction of Particle Movement (Push/Pull) Direction of Particle Movement (Side to Side) Moves through liquids and solids Stop when they reach a liquid medium

36. P Wave Shadow Zone

37. S Wave Shadow Zone

38. ESRT Time/Travel Graph P and S Waves

39. Sample Regents Problem

40. ESRT Time/Travel Graph S - P = Lag Time (3 min.)

41. Calculate Distance from Seismic Station to Epicenter of EQ Using ESRT

42. Let’s try it another way…

43. ESRT Time/Travel Graph P and S Waves 7 min

44. Here’s Another One… 8/07 test

45. Take difference between P arrival and S arrival

46. And…..

48. Let’s Be Virtual Seismologists! Virtual Earthquake - An Introduction Virtual Earthquake - An Introduction Virtual Earthquake - An Introduction Virtual Earthquake - An Introduction