1. The December 26, 2004 M w 9.0 Western Sumatra Earthquake and Tsunami Michael Bunds Department of Earth Science Utah Valley State College

2. The Earthquake’s Statistics Magnitude 9.0 (Mw) Sunday, December 26, 2004 at 00:58:53 (UTC) Sunday, December 26, 2004 at 7:58:53 AM local time at epicenter Saturday, December 25, 2004 at 5:58:53 PM Mountain Standard Time Energy Released = 2 x 10 17 Joules Equivalent to 475 megatons of TNT or 23,000 Hiroshima bombs Tsunami energy estimate = 10 14 Joules (10 Hiroshima bombs) Over 225,000 fatalities, 5 million homeless people in Indian Ocean – most as a result of earthquake-induced tsunami

3. The Earthquake in Historical Context Four Largest Earthquakes on Record 1.M 9.5 Chile, 1960 2.M 9.2 Prince William Sound, Alaska 1964 3.M 9.1 Andreanof Islands, Alaska, 1957 4.M 9.0 Kamchatka, 1952 5.M 9.0 Sumatra, 2004 1 2 3 4 5 10 of 11 largest on subduction zone megathrusts surrounding Pacific Ocean Most deadly tsunami recorded history

4. Phuket Epicenter Sri Lanka Sumatra Asia CHINA RUSSIA INDIA

5. Phuket Banda Aceh Epicenter Southeast Asia Sri Lanka

7. U.S.G.S Tectonic Setting

10. Subduction Zone

12. Destructive historical tsunamis at the western coast of Sumatra 1797/02/10 M>8.0 Central part of the western Sumatra. Padang was flooded by powerful waves. More then 300 fatalities. 1833/11/24 M=8.8-9.2 South coast of the western Sumatra. Huge tidal wave flooded all southern part of the western Sumatra. Numerous victims. 1843/01/05 M=7.2 Terrible wave came from the south- east and flooded all the coast of the Nias Island. Many fatalities. 1861/02/16 M>8.2 Several thousand fatalities.

13. What is an Earthquake? Ground shaking caused by a sudden release of energy within Earth. Most result from slip on a fault. Elastic Rebound

14. Hypocenter and Epicenter epicenter hypocenter fault

15. Original Position 200 to 500 years later Overriding crust flexes 10 to 50 meters, storing energy to be released in earthquake During earthquake Overriding crust snaps back to original position 200 – 250 km wide areas uplift and subside Subsidence Uplift Sumatra Andaman Isl.

16. M9.0 Epicenter U.S.G.S Aftershocks (yellow circles) outline ruptured area on fault ~1200 km by 200 km area of fault ruptured

17. U.S.G.S Expected Areas of Uplift and Subsidence Andaman Islands Probable area of subsidence Probable area of uplift

18. Andaman Islands Probable tectonic uplift from earthquake Andaman Islands Probable tectonic uplift from earthquake Before After

19. Andaman Islands Probable tectonic uplift from earthquake Andaman Islands Probable tectonic uplift from earthquake Before After Submerged coral reef Emergent coral reef

20. Probable Tectonic Subsidence in Banda Aceh, Sumatra earthobservatory.nasa.gov

21. Comparison of Sumatra Earthquake Fault Rupture Area to Cascadia Subduction Zone

22. U.S.G.S Seismicity in Area 1900 – 2002, M > 6

23. Seafloor Displacement in Earthquake Vertical uplift 5 m max. Horizontal movement 11 m max. Cal Tech

24. Generalized Tsunami Wave Characteristics Usually more than one wave is created In open ocean –Wavelength: 200 to 250 km (dist. between wave peaks) –Wave height: 0.5 m –Speed: 700 km/hr –Period: 17 minutes (time between wave peaks) Near shore –Wavelength: 10 km –Wave height: meters to tens of meters –Speed: 36 km/hr –Period: 17 minutes (time between wave peaks)

25. Waves Compress as They Near Land Waveheight increases Wavelength decreases But tsunamis do not break like the pictured wind waves

26. Wind waves are tall and short wavelength Tsunamis often are no taller than wind waves, but involve much more water due to long wavelength

27. Low Water Preceding Tsunami Wave in Sri Lanka Usual water level earthobservatory.nasa.gov

29. Sri Lanka

30. People Collecting Fish During Low Water Preceding a Tsunami. Oahu, Hawaii, 1957

31. U.S.G.S

32. Variations in Tsunami Intensity An individual tsunami can have vastly different heights in different places depending upon: –Distance and direction from source –Wave source directivity (most wave energy was directed east and west) –Configuration of local seafloor and coastline –Shielding by other landmasses

33. A. Piatenesi, Tsunami Research Lab, Russia Calculated Maximum Water Height

34. Sumatra, north-west coast10-15 m Sri Lanka, east coast5-10 m Thailand (incl. Phuket)3-10 m India, east coast5-6 m Andaman Islands> 5 m Kenya2-3 m Sumatran Tsunami Maximum Heights Additional Factor: In Thailand and Sumatra tsunami closely coincided with highest tide for the month

35. Phuket Banda Aceh Epicenter Southeast Asia Sri Lanka

36. earthobservatory.nasa.gov

37. Sri Lanka

39. Banda Aceh

40. Banda Aceh, Sumatra

41. earthobservatory.nasa.gov before after

42. Banda Aceh, Sumatra earthobservatory.nasa.gov before after

43. Banda Aceh, Sumatra earthobservatory.nasa.gov before after

44. Banda Aceh, Sumatra (before)

45. Banda Aceh, Sumatra (after) earthobservatory.nasa.gov

46. Khao Lak earthobservatory.nasa.gov before after

47. Banda Aceh, Sumatra (before) earthobservatory.nasa.gov

48. Banda Aceh, Sumatra (after) earthobservatory.nasa.gov

49. Banda Aceh, Sumatra (before) earthobservatory.nasa.gov

50. Banda Aceh, Sumatra (after) earthobservatory.nasa.gov

51. Lessons and Conclusions The earthquake and tsunami were not surprises Great earthquakes and tsunamis are rare but devastating Tsunami warning systems can save many lives If you are at the beach and you feel an earthquake, head for higher ground immediately