The M9.0 Andaman Islands-Sumatra Earthquake and Tsunami of 26 December 2004

1. The M9.0 Andaman Islands-Sumatra Earthquake and Tsunami of 26 December 2004 Prof. L. Braile,braile@purdue.edu, web.ics.purdue.edu/~braile (last modified March 20, 2006) (Despite the popularity of this image, tsunami waves do not normally look like this.)

2. Tectonic Setting USGS

3. Schematic plate tectonic setting for tsunami generation TRENCH NOAA Commonly, in mega-thrust earthquakes, a very large area of the ocean floor is uplifted

4. Historical Seismicity (Indonesia is one of the most seismically active areas in the world, has a long subduction zone plate boundary, and many 7+ earthquakes have occurred there in the past, so it should be no surprise that an M9+ tsunami-generating event would occur there.)

5. Tsunami-generating EQs and sources Geist, Titov and Synolakis, Tsunami: Wave of Change, Scientific American, January, 2006.

6. Sumatra earthquakes FAQs Question: What other great (M > 8) earthquakes have occurred in the region? Answer: Since 1900 and prior to the December 26 earthquake, the largest earthquake along the subduction zone from southern Sumatra to the Andaman Islands occurred in 2000 and had a magnitude of 7.9.  A magnitude 8.4 earthquake occurred in 1797, a magnitude 8.5 in 1861 and a magnitude 8.7 in 1833 . All three ruptured sections of the subduction zone to the south of the recent earthquake.  Interestingly, the 1797 and 1833 quakes are believed to have ruptured roughly the same area with only 36 years separating the events. Paleoseismic evidence shows that great earthquakes or earthquake couplets occur about every 230 years (http://www.gps.caltech.edu/~sieh/publications/a10.html). USGS

7. Show earthquake activity in Indonesia and aftershocks of the 26 December earthquake using the Seismic Eruption program (written by Alan Jones, SUNY-Binghamton) http://www.geol.binghamton.edu/faculty/jones/

8. Main shock and aftershocks ~1200 km of the plate boundary moved, max. displacement ~ 15 m (?, preliminary est.) USGS

9. 24-hour seismograph record ~135 degrees distance

10. Seismogram

11. Surface waves around the world

12. Worldwide earthquakes per year (from USGS):

13. Worldwide earthquakes per year: Frequency-magnitude relationship suggests that magnitude 9+ events will occur about once per decade; statistically, since 1900, the actual number is ~once per 20 years.

15. Magnitude of earthquake is controlled by fault length that ruptures (data for diagram generated using Seismic/Eruption program) Magnitude versus fault length Magnitude versus fault length (determined from aftershock zone length) for various earthquakes (Alaska, 1964; Denali, 2002; Landers, 1992; Loma Prieta, 1989; Northridge, 1994, etc.). Results were quickly obtained using Seismic/Eruption views. Alaska, 1964 Sumatra, 2004 Denali, 2002 Landers, 1992 Loma Prieta, 1989 Northridge, 1994

16. Largest earthquakes, 1900 - 2004 USGS

17. Largest earthquakes, 1900 - 2004 USGS

19. Some recent Tsunamis NOAA

20. Some Notable Tsunamis

21. Question: What other significant tsunamis have occurred in the region? Answer: The following destructive tsunamis are listed on a data base maintained by the Tsunami Laboratory, Institute of Computational Mathematics and Mathematical Geophysics (http://tsun.sscc.ru/tsulab/20041226tsun.htm) 1. 1797/02/10 Central part of the western Sumatra. The quake was most felt near Padang and in the area within +/-2 deg of equator. Padang was flooded by powerful waves. More then 300 fatalities. 2. 1833/11/24 South coast of the western Sumatra, estimated rupture from 1 S to 6 S latitude. Huge tidal wave flooded all southern part of the western Sumatra. Numerous victims. 3. 1843/01/05 Strong earthquake west of the central Sumatra. Terrible wave came from the south-east and flooded all the coast of the Nias Island. Many fatalities. 4.  1861/02/16 Exceptionally strong earthquake affected all the western coast of Sumatra. Several thousand fatalities. 5. 1883 Krakatau explosion 36,000 fatalities USGS

22. Tsunami travel time (hours; simulation) NOAA

23. Tsunami wave height (cm; simulation) NOAA

24. 26 Dec. 2004 Tsunami max. wave height and arrival time Geist, Titov and Synolakis, Tsunami: Wave of Change, Scientific American, January, 2006.

25. Tsunami wave height (2 hours after earthquake) measured from satellite radar altimetry NOAA

26. Satellite radar altimetry

27. Satellite radar altimetry Gower, J., EOS, v. 86, no. 4, 25 January, 2005

28. Tide gauge record, east coast of India Tsunami (~1.2 m maximum wave height; note that waves are visible for over 2 days) Normal tide variation

29. Wave Heights – Satellite observation versus calculated model Geist, Titov and Synolakis, Tsunami: Wave of Change, Scientific American, January, 2006.

30. Tsunami wave propagation characteristics – note that as water depth becomes smaller, waves slow down, become shorter wavelength, and have larger amplitude NOAA When the water is 10 m deep, what is the separation of the waves in minutes?

31. Water waves animation Direction of propagation Animation courtesy of Dr. Dan Russell, Kettering University http://www.gmi.edu/~drussell/demos.html

32. Tsunami simulation http://staff.aist.go.jp/kenji.satake/animation.gif

33. Tsunami simulations Open Quick Time simulations (see these websites) http://www.pmel.noaa.gov/tsunami/ http://www.pmel.noaa.gov/tsunami/Mov/TITOV-INDO2004.mov http://es.ucsc.edu/~ward/indo.mov Note distance of propagation and reflection of waves

34. Double click on the file: TITOV-INDO2004[1].mov To view Quick Time movie of Tsunami simulation from NOAA http://www.pmel.noaa.gov/tsunami/Mov/TITOV-INDO2004.mov Also, simulation from S. Ward, UCSC: indo[1].mov http://es.ucsc.edu/~ward/indo.mov

35. Show video segments of tsunami waves and damage Source: http://www.asiantsunamivideos.com/

37. Chedi Resort, Phuket, Thailand, wave height ~4+ m (?, from estimates of water level from beach umbrellas on grassy area above the beach)

38. Damage in Banda Aceh

39. Earthquake and Tsunami Damage, Banda Aceh, Sumatra

40. Earthquake and Tsunami Damage, Sri Lanka

41. Train and tracks destroyed, SW coast of Sri Lanka Geist, Titov and Synolakis, Tsunami: Wave of Change, Scientific American, January, 2006.

42. Tsunami wave trough, Sri Lanka coast

43. Commonly, the water recedes (a wave trough) significantly for a few minutes before the first wave crest arrives. People often go out to explore the beach or gather fish or shells at that time.

44. Tsunami wave, Sri Lanka; note strong current

45. Banda Aceh, Sumatra, before tsunami http://geo-world.org/tsunami/

46. Banda Aceh, Sumatra, after tsunami Also: http://www.digitalglobe.com/

47. Factors that increased loss of life and damage 1. Magnitude of earthquake – largest event in 40 years; and location near highly populated coastlines. 2. Approximately north-south orientation of the plate boundary that focused energy to the west and east.

49. 3. Location off the coast of Sumatra (?) N. Sumatra west coast S. Am.

50. 4. the lack of a tsunami warning system and adequate rapid communication systems