1. Earthquakes

2. What is an Earthquake? 3. Elastic Rebound 4. Stress vs. TimeStress 5. Epicenter vs. Focus 6. Types of Seismic WavesBody WavesSurface Waves 7. Primary (P) WavesLongitudinal (forward) motionMove by compression & expansionFastest of the wave typesTravel through solids & liquids 8. Secondary (S) WavesShear (sideways) motionMove by lateral displacementSecond fastest of the wave typesTravel through solids only 9. Love (L) WavesShear (sideways) motionMove by lateral displacementSecond slowest of the wave typesTravel through solids only 10. Rayleigh (R) WavesElliptical motionMove by rotational displacementSlowest of the wave typesTravel through solids and liquids 11. Where Do Earthquakes Occur? 12. Plate BoundariesFrom Tarbuck and LutgensDivergentTransformConvergent 13. Benioff Zones 14. Types of MovementDivergent PlateBoundaryConvergent PlateBoundaryTransform PlateBoundary 15. FaultsFaults are fractures along which there has been vertical and/orhorizontal movement. 16. NormalReverseTypes of FaultsStrike-slipFaults are classified by the relative direction of movement of therocks on either side with respect to each other side. 17. Normal FaultsNormal faults form as a result of tension. The hanging wallmoves downward with respect to the footwall. They arereferred to as normal because they appear to have slipped inresponse to gravitational forces. 18. Mountain and Valley TopographyA characteristic of normal faulting in highly extensionalterrains, such as continental divergent plate boundaries, is thatof alternating mountain ranges (horsts) and valleys (grabens). 19. Reverse FaultsReverse faults form as a result of compression. The hangingwall moves upward with respect to the footwall. They arereferred to as reverse because they demonstrate the oppositemotion of normal faults. 20. Thrust FaultsThrust faults are reverse faults with a low dip angle. They areoften associated with folding and are typically found inassociation with convergent plate boundaries. 21. Strike-slip FaultsStrike-slip faults form as a result of lateral shearing. The twosides of the fault move laterally past one another. 22. Methods of MeasurementRichter Scale Mercalli ScaleCharles Richter Giuseppe MercalliMeasures energy releasedDetermined by wave amplitudeMeasures intensityDetermined by degree of damageWe now use the moment magnitude Now referred to as the modified Mercalli Scale 23. QuickTime and aPhoto - JPEG decompressorare needed to see this picture. 24. Qui ckTi me and aPhoto - JPEG decompressorare needed to see this picture.The largest recorded earthquakes: Chile, 1960 8.3 on the Richter Scale, Mw= 9.5Alaska, 1964 8.4 on the Richter Scale, Mw= 9.2For each unit-increase in magnitude: Ground Shaking increases by a power of 10 (10x)Energy released increases by a power of 30 (30x) 25. Largest Earthquakes in the World Since 1900Location Date UTC Magnitude Coordinates1. Chile 1960 05 22 9.5 38.24 S 73.05 W2. Prince William Sound, Alaska 1964 03 28 9.2 61.02 N 147.65 W3. Andreanof Islands, Alaska 1957 03 09 9.1 51.56 N 175.39 W4. Kamchatka 1952 11 04 9.0 52.76 N 160.06 E5. Off the West Coast of Northern Sumatra 2004 12 26 9.0* 3.30 N 95.78 E6. Off the Coast of Ecuador 1906 01 31 8.8 1.0 N 81.5 W7. Rat Islands, Alaska 1965 02 04 8.7 51.21 N 178.50 E8. Assam - Tibet 1950 08 15 8.6 28.5 N 96.5 E9. Kamchatka 1923 02 03 8.5 54.0 N 161.0 E10. Banda Sea, Indonesia 1938 02 01 8.5 5.05 S 131.62 E11. Kuril Islands 1963 10 13 8.5 44.9 N 149.6 E*now 9.3 26. Table 4-1, p. 87(possibly 750,000) 27. Qui c kTi me and aPhoto - JPEG decompressorare needed to see this picture. 28. Earthquake DestructionIntensity map for the1886 CharlestonEarthquakeEarthquake destruction takes a variety of forms, depending upongeological setting, strength of the quake, and the nature of construction. 29. U.S. Earthquake Risk 30. Ground Rupture 31. Qui ckTi me and aPhoto - JPEG decompressorare needed to see this picture. 32. QuickTime and aPhoto - JPEG decompressorare needed to see this picture. 33. Ground ShakingQuickTime and aPhoto - JPEG decompressorare needed to see this picture. 34. LiquifactionJapan 1964 35. Mexico City 1985 36. Indirect Damage 37. San Francisco1999 38. LandslidesQ uickT ime and aPhoto - JPEG decompressorare needed to see this picture. 39. Landslides (slumping)Alaska 1964 Alaska 1964 40. Tsunamis 41. Historical RecordsPlotting of historical earthquakes (location and size) can be used topredict the degree of likely hazard for a given area. 42. Geologic HistoryTrenching and drilling along and across a fault can give us an idea ofhow often and how frequently it has moved in the past.Video 11:38 15:32 43. Seismic Gaps 44. Stress vs. TimeStress 45. M 9.1Dec. 2004M 8.8Feb. 2010M 7.0Jan. 2010M 8.1Sep. 2009M 9.0Mar. 2011 46. Fault Asperity 47. Characterisic Quakes1910 AD200 AD 48. Earthquake FrequencyUSGS PAGERCAT 1900-2008, USGS-NEIC & gCMT 2008-presentPlot of number of earthquakes M7.5 and larger since 1900. 49. Fore- and AftershocksTiming and magnitude of earthquakes for Tohoku, Japan. 50. Mitigation 51. p. 105c 52. Fig. 4-40, p. 101Base Isolators 53. p. 105b 54. p. 105a 55. p. 105d 56. Tsunami DetectionVideo 24:19 35:23