1. Ch 19 Earthquakes Shake, Rattle, and Roll!

2. Lesson 7 Forces and Faults

3. Think About It… What happens to a rubber band that is stretched past its elastic limit?

4. Focus Question… What causes earthquakes?

5. A. Stress and Strain… What are earthquakes? natural vibrations of the ground caused by movement along gigantic fractures in Earth’s crust

6. Stress and Strain… 1. When do most earthquakes occur? when rocks fracture (break) deep within Earth 2. When do fractures form? when stress exceeds the strength of the rocks involved

7. Stress and Strain… 3. What is stress? … the forces per unit area acting on a material … There are three types of stress.

8. Stress Compression decreases the volume of a material – occurs at convergent boundaries http://rst.gsfc.nasa.gov/Sect2/05-01_reverse_fault-jyougashima_DSC8766.jpg

9. Stress! Tension pulls a material apart – at divergent boundaries

10. Stress! Shear (horizontal) causes a material to twist – at transform boundaries. http://rpmedia.ask.com/ts?u=/wikipedia/commons/thumb/b/b1/Boudin_vein.jpg/180px-Boudin_vein.jpg

11. Strain! 5. What is strain? the deformation of materials in response to stress It is represented by the solid line on your diagrams.

12. Elastic Limit 6. A slab of rock’s elastic limit is… … the point at which it will undergo permanent deformation 7. Failure is… … when a material breaks! We call this failure an earthquake!

13. Faults… 1.Rocks will fail and form a fault…when stress is applied too quickly or when stress is great 2.A fault is the resulting fracture (or system of fractures) along which movement occurs.

14. Reverse Fault…  Is caused by… compression (at a convergent boundary)  Movement of crust… block above fault moves up and over http://www.iris.edu/gifs/anim ations/faults.htm http://homepage.ufp.pt/biblioteca/GlossarySaltTectonics/PlatesJPG/Fig.R018-ReverseFault.jpg

15. Reverse Fault – The Himalayas! http://www.geographicguide.net/earth/pictures/himalayas-asia.jpg http://img.wylio.com/flickr/500/494666903

16. Normal Fault…  Is caused by… tension (at a divergent boundary)  Movement of crust… block above fault moves down http://www.iris.edu/gifs/animations/faults.htm http://geology1a-1.wikispaces.com/file/view/NormalFault.gif/90969209/NormalFault.gif

17. Normal Fault – The Sierra Nevadas http://fela2fela.files.wordpress.com/2012/02/sierra-nevadas.jpg http://www.pbs.org/weta/thewest/places/states/california/ca_sierra.jpg

18. Strike-slip Fault…  Is caused by… horizontal shear (at a transform boundary)  Movement of crust… blocks slide past each other horizontal (no vertical movement) http://www.iris.edu/gifs/animations/faults.htm http://7bcore3.wikispaces.com/file/view/StrikeSlipLLFault%5B1%5D.gif/193098468/StrikeSlipLLFault%5B1%5D.gif

19. The San Andreas Fault…  http://www.sanandreasfault.org/ http://www.sanandreasfault.org/

20. Lesson 8 Seismic Waves and Earth’s Interior

21. Think About It… Is it possible to go to Earth’s core?

22. Focus Question… What are seismic waves and what can we learn from a travel-time graph?

23. The Focus of an Earthquake… 1.The focus of an earthquake is where the rocks break at least several miles beneath Earth’s surface. 2.The epicenter is the location on Earth’s surface just above the focus. http://www.em.gov.bc.ca/Mining/Geoscience/SurficialGeologyandHazards/Earthquakes/PublishingImages/eq-2b.gif 2. Draw the picture.

24. The Focus of an Earthquake… http://www.em.gov.bc.ca/Mining/Geoscience/SurficialGeologyandHazards/Earthquakes/PublishingImages/eq-2b.gif

25. Earthquake Waves… 1. What are seismic waves? vibrations of the ground during an earthquake Seismic Wave Rap! http://www.youtu be.com/watch?v= x1tb6HwyaHg http://gomyclass.com/geology10/files/lecture9/html/web_data/file22.htm

26. Earthquake Waves… 2. How do the following types of seismic waves move rocks? a. Primary (P) waves – squeeze (push) & pull rocks in the same direction as the wave http://www.youtube.com/watch?v=2rYjlVPU9U4 http://allshookup.org/quakes/wavetype.htm

27. Earthquake Waves… 2. How do the following types of seismic waves move rocks? b. Secondary (S) waves – cause rocks to move at right angles to direction of the wave http://www.youtube.com/watch?v=en4HptC0mQ4

28. Earthquake Waves… c. Surface waves – move in 2 directions – up and down and side to side (slowest and most damaging!)

29. Seismic Waves and a Seismogram…  http://www.geo.mtu.edu/UPSeis/reading.html http://www.geo.mtu.edu/UPSeis/reading.html “So which wiggles are the earthquake? The P wave will be the first wiggle that is bigger than the rest of the little ones (the microseisms). Because P waves are the fastest seismic waves, they will usually be the first ones that your seismograph records. The next set of seismic waves on your seismogram will be the S waves. These are usually bigger than the P waves. The surface waves are the other, often larger, waves marked on the seismogram. Surface waves travel a little slower than S waves (which, in turn, are slower than P waves) so they tend to arrive at the seismograph just after the S waves.”

30. Seismogram (Add to notes) http://www.sms-tsunami- warning.com/pages/seismo graph#.VFpac3JdVps

31. Travel-Time Graph (not time travel!) 1. A travel-time graph is … shows average travel time of P & S waves 2. This graph is used to calculate… the distance to the epicenter (using the difference in arrival times of the p and s waves) http://mtweb.mtsu.edu/cribb/100eq.html

32. Travel-Time Curves (p. 501) Suppose the waves recorded on a seismogram at Station A are farther apart than they are at Station B… The epicenter is farther from Station A. Animation for Lab 8 on next slide 

33. Lab Lesson 8 Animation of Waves… http://aspire.cosmic- ray.org/Labs/SeismicWaves/

34. Lesson 9 Measuring and Locating Earthquakes

35. Think About It… What is the strongest earthquake that has happened in your lifetime?

36. Focus Question… How are earthquakes measured and located?

37. Earthquake Magnitude and Intensity How is the amount of energy released by an earthquake measured? by its magnitude Haiti, 1/2010 (7)

38. The Richter Scale… a. The Richter scale is based on… size of the largest seismic waves generated by the quake (EQ) b. Each successive number on this scale represents… a 10 times increase in wave size c. Each increase in magnitude corresponds to… A 32-times increase in seismic energy d. A magnitude 8 EQ releases 32 times more energy than a magnitude 7 EQ.

39. The Richter Scale http://sahanasingh.wordpress.com/2011/05/17/failing-to-prepare/ Haiti, 1/2010 (7) Japan, 3/2011 (9)

40. The Modified Mercalli Scale… a. The intensity of an earthquake can be determined by… amount of damage done to the structures involved (intensity) b. The modified Mercalli scale is used to determine the intensity of an EQ by… rate damage & other effects as noted by observers This scale uses Roman numerals from I to XII. It was developed by Giuseppe Mercalli in 1902. http://www.geo.mtu.edu/UPSeis/intensity.html

41. Modified Mercalli Scale… Did you feel it? usgs.gov http://scearthquakes.cofc.edu/images/MercalRichtscale.gif http://earthquake.u sgs.gov/earthquake s/eventpage/dyfi/?e nabled=false

42. Measuring Earthquakes: The Basics  http://www.youtube.com/watch?v=Nl8v1i SRtxA http://www.youtube.com/watch?v=Nl8v1i SRtxA

43. Modified Mercalli Scale… d. A seismic intensity map is made by… … compile the MMsI values (Modified Mercalli scale intensity values), plot them on a map, & join points of similar intensity. (See map on back.) Mercalli values at distances very far from the epicenter… Decrease to I

44. Seismic Intensity Map… Northridge, California Earthquake

45. http://seismo.berkeley.edu/blogs/seismoblog.php/2009/01/17/today-in-earthquake-history-northridge-1994 http://www.weldreality.com/northridge-earthquake-4.jpg Damage in Northridge, Ca…

46. More Damage in Northridge, Ca…

47. Depth of Focus… e. Another factor that determines the intensity of an earthquake is … The depth of an EQ’s focus Shallow-focus events will produce catastrophic quakes with high intensity values.

48. Locating an Earthquake… 1. The distance to an earthquake’s epicenter is determined by… the time difference b/tw the arrival of the P-wave & the S-wave 2. This distance is called… Epicentral distance 3. Three seismograph stations are needed to determine an EQ’s epicenter.

49. Locating an Earthquake…  http://www.geo.mtu.edu/UPSeis/images/triangle.gif 5. A travel-time graph determines the exact time of an EQ. 3. Three seismograph stations are needed to determine an EQ’s epicenter.

50. Seismic Belts… p. 510 1. Most earthquakes are associated with… Tectonic plate boundaries 2. 80% of earthquakes occur in… The Circum-Pacific Belt 3. Another 15% of earthquakes occur at the Mediterranean-Asian Belt 4. Most of the remaining earthquakes occur at mid-ocean ridges http://earthquake.usgs.gov/

51.  http://oceanworld.tamu.edu/resources/oceanography-book/earthquakes.htm

53. Reinforcement 9…

54. Lab 9 USA Map… http://www.worldatlas.com/geoquiz/mississi.gif

55. Lesson 10 Earthquake Hazards

56. Think About It… Why do developing countries such as Haiti suffer such devastation from earthquakes?

57. Focus Question… How do earthquakes affect the four spheres of Earth?

58. Structural Failure… 1. The types of buildings that sustain the most severe damage from earthquakes are… Unreinforced, made of stone, concrete, or other brittle materials Typical building in Iraq http://www.siampinoy.net/forum/55-ano-ba-ang-latest-post-it-here/88292-chile-earthquake-may-have-shortened-days-on-earth.html Church, Armenia, 1988

59. Unreinforced Masonry Building: A Mission in California

61. Structural Failure… 2. The types of buildings that sustain the least amount of damage from earthquakes are… wooden high-rise, steel-framed Kobe, Japan 1995

62. Structural Failure… 3. Pancaking is… supporting walls of ground floor collapse causing upper floors to collapse Pancaked Building in Turkey

63. Structural Failure… 4. Building with 5- 15 stories may collapse because… their natural sway has the same vibration period of an EQ http://www.wbdg.org/resources/seismic_design.php

64. Preventing Structural Failure, Golden Gate Bridge, CA

66. Land and Soil Failure… 5. Earthquakes in sloping areas can trigger… landslides! El Salvador, 2001, mag 7.6

67. Land and Soil Failure 6. Soil liquefaction subsurface materials liquefy & behave like quicksand due to EQ vibrations http://earthquake.usgs.gov/learn/animation s/animation.php?flash_title=Liquefacti on&flash_file=liquefaction&flash_width =450&flash_height=200 http://en.wikipedia.org/wiki/Soil_liquefaction

69. Animation of Liquefaction… http://www.youtube.com/watch?v=536xSZ_XkSs

70. Land and Soil Failure… 7. T here was much damage to structures in the Mexico City EQ of 1985 b/c... It is built on soft sediments. http://seismo.berkeley.edu/blogs/seismoblog.php/2008/09/19/title

72. Fault Scarps… 8. A fault scarp is… area of great vertical offset where the fault intersects Earth’s surface. 9. The fault scarp shown created a… waterfall

73. Tsunamis… 10. A tsunami is caused by… vertical motion of seafloor (during the EQ) bumps the water over the fault 11. A tsunami in the open ocean is usually… 1 meter high (3 ft) You wouldn’t notice it if you were there! Tsunami strikes Ao Nang, ThailandAo Nang http://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami

74. Tsunamis… 12. A tsunami is dangerous when it enters shallow water because… it moves very fast it can be very high – up to 30m (90 ft)! Sri Lanka, 2004

76. Tsunamis… 13. The most recent devastating tsunami was in… Japan, March 2011 Youtube Clip: https://www.youtub e.com/watch?v=V2t aJExhV6g https://www.youtub e.com/watch?v=V2t aJExhV6g

78. http://www.youtube.com/watch?v=0uncX 5H9oEQ One and a half minute clip of a tsunami drill in Oregon.

79. Tsunami Warning Sign in Monterey, CA

80. Tsunami Evacuation, Washington State

81. Warning Sign in Astoria, Oregon!

82. Seismic Risk… 14a. Five states with the greatest seismic risk… Alaska California Hawaii Utah Nevada b. The San Andreas Fault is a transform boundary. http://pubs.usgs.gov/fs/2005/3052/images/map.jpg

83. Seismic Risk… 14c. The seismic risk of the NC Piedmont and mountains… moderate 14d. The seismic risk of the coastal plains of NC… low

84. Seismic Risk in the USA

85. Earthquake Prediction… 15. Earthquake recurrence rates indicate … Where EQs happen (occur) repeatedly (at regular intervals to generate similar quakes)

86. Earthquake Prediction… 16. Seismic gaps are sections of active faults that haven’t had big EQs for a while An earthquake is likely to happen here! The San Andreas Fault http://upload.wikimedia.org/wikipedia/commons/8/8d/San_Andreas.jpg

87. Earthquake Prediction… 17. Why is earthquake prediction important? … to save lives and prevent property damage!! http://www.youtube.com/watch?v=_YLjIvJXhpg San Andreas Fault

88. Extra Slides that discuss Earth’s Interior…

89. F. Clues to Earth’s Interior (p. 503) 1. Where does the knowledge of Earth’s interior come from? The study of seismic waves 2. How do P-waves and S-waves move through the mantle? They follow fairly direct paths 3. What do P-waves do when they strike the core? They bend 4. Why don’t S-waves enter Earth’s core? They cannot travel through liquids

90. Clues to Earth’s Interior 5. What does the disappearance of S- waves tell us about Earth’s outer core? That it must be liquid 6. What shows us that Earth’s inner core is solid? Studies of how P waves are deflected deep within Earth http://www.columbia.edu/~vjd1/ray_paths.gif

91. G. Earth’s Internal Structure…  Crust of lithosphere – granite (continental crust), basalt (oceanic crust)  Upper mantle – peridotite (intrusive, bumpy, igneous)  Asthenosphere – peridotite  Lower mantle – oxides of iron, silicon, and magnesium  Core – iron and nickel (magnetic field is generated here!

92. G. Earth’s Internal Structure … http://astronomy.nju.edu.cn/~lixd/GA/AT4/AT407/HTML/AT40703.htm