The M9.0 Andaman Islands-Sumatra Earthquake and Tsunami of 26 December 2004 Discovery Lecture, Dept. of Earth and Atmospheric Sciences, Purdue University February 28, 2005

Prof. Larry Braile, braile@purdue.edu, www.eas.purdue.edu/~braile(Despite the popularity of this image, tsunami waves do not normally look like this.)

Tectonic SettingUSGS

Schematic plate tectonic setting for tsunami generationNOAACommonly, in mega-thrust earthquakes, a very large area of the ocean floor is upliftedTRENCH

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.)

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). USGSSumatra earthquakes FAQs

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/

USGSMain shock and aftershocks

~1200 km of the plate boundary moved, max. displacement ~ 15 m (?, preliminary est.)

24-hour seismograph record~135 degrees distance

Seismogram

Surface waves around the world

Worldwide earthquakes per year (from USGS):

DescriptorMagnitudeAverage AnnuallyGreat8 and higher1 Major7 - 7.917 Strong6 - 6.9134 Moderate5 - 5.91319 Light4 - 4.913,000 (est.)Minor3 - 3.9130,000 (est.)Very Minor2 - 2.91,300,000 (est.) Based on observations since 1900. Based on observations since 1990.

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.

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

Chart1

1400

1200

70

330

40

100

25

15

22

Magnitude

Fault Length (km)

Magnitude versus Fault Length

Sheet1

9.21400

91200

770

7.9330

6.840

7.5100

6.425

6.115

6.322

Sheet1

Magnitude

Fault Length (km)

Magnitude versus Fault Length

Sheet2

Sheet3

Largest earthquakes, 1900 - 2004USGS

Largest earthquakes, 1900 - 2004USGS

LocationDate UTCMagnitude Coordinates1.Chile1960 05 22 9.538.24 S73.05 W2.Prince William Sound, Alaska1964 03 28 9.261.02 N147.65 W3.Andreanof Islands, Alaska1957 03 09 9.151.56 N175.39 W4.Kamchatka1952 11 04 9.052.76 N160.06 E5.Off the West Coast of Northern Sumatra2004 12 26 9.03.30 N95.78 E6.Off the Coast of Ecuador1906 01 31 8.81.0 N81.5 W7.Rat Islands, Alaska1965 02 04 8.751.21 N178.50 E8.Assam - Tibet1950 08 15 8.628.5 N96.5 E9.Kamchatka1923 02 03 8.554.0 N161.0 E10.Banda Sea, Indonesia1938 02 01 8.55.05 S131.62 E11.Kuril Islands1963 10 13 8.544.9 N149.6 E

Some recent TsunamisNOAA

DateMagn.Max HtKilledLocationComments9-2-927.210 m170NicaraguaMeasured Pacific-wide12-12-927.526 m 1000Flores Island7-12-937.630 m200Hokkaido6-2-947.214 m220Java10-4-948.111 m11Kuril IslandsMeasured Pacific-wide11-14-94 7.1 7 m 70 Mindoro02-21-96 7.5 5 m 12 Peru07-17-98 7.0 15 m 2000 New Guinea06-23-01 8.3 5 m 50 PeruMeasured Pacific-wide

Some Notable Tsunamis

DateMagn.Max. Ht.KilledLocationComments5-22-17827.010 m40000Taiwan11-22-18157.0?10253Indonesia8-27-1883 -35 m36000IndonesiaKrakatau Eruption1-21-19176.5?15000Indonesia4-1-19467.935 m173AleutiansMany deaths in Hilo, Hawaii5-22-19609.525 m 534ChileLargest historical earthquake3-28-1964 9.2 67 m 115Alaska2-4-19767.5 ? 22778 Guatemala12-26-20049.015 m ~217,000 (4/8/05 est.)N. SumatraGreatest number of fatalities

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

Tsunami travel time (hours; simulation)NOAA

Tsunami wave height (cm; simulation)NOAA

Tsunami wave height (2 hours after earthquake) measured from satellite radar altimetryNOAA

Satellite radar altimetry

Satellite radar altimetryGower, J., EOS, v. 86, no. 4, 25 January, 2005

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

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

Tsunami simulationhttp://staff.aist.go.jp/kenji.satake/animation.gif

Tsunami simulationsOpen 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

Double click on the file: TITOV-INDO2004[1].movTo view Quick Time movie of Tsunami simulation from NOAAhttp://www.pmel.noaa.gov/tsunami/Mov/TITOV-INDO2004.mov

Also, simulation from S. Ward, UCSC: indo[1].movhttp://es.ucsc.edu/~ward/indo.mov

Show video segments of tsunami waves and damage

Source: http://www.asiantsunamivideos.com/

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

Damage in Banda Aceh

Earthquake and Tsunami Damage, Banda Aceh, Sumatra

Earthquake and Tsunami Damage, Sri Lanka

Tsunami wave trough, Sri Lanka coast

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.

Tsunami wave, Sri Lanka; note strong current

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

Banda Aceh, Sumatra, after tsunamiAlso: http://www.digitalglobe.com/

Factors that increased loss of life and damage1. 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.

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

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

DART tsunami warning systemNOAADART: Deep ocean Assessment and Reporting of Tsunamis

5. the lack of adequate public awareness of tsunamis and tsunami hazards(Although the 26 December 2004 earthquake and tsunami was a tragic event, two benefits are: that countries are now committed to installing effective tsunami warning systems worldwide, and, there is greatly increased public awareness of tsunamis and tsunami hazards.)

Many people watched the waves approach and did not take action until too late, or went out to explore the beach during a wave trough

6. the common building construction characteristics in developing countries

Some significant observations and occurrencesTsunami warning system could have saved many lives (many deaths occurred as tsunami hit over two hours after the earthquake).In Sumatra, experiencing the strong earthquake caused some people to move to higher ground; however, many did not.Apparently, many animals sensed the seismic waves, the sound of the tsunami waves approaching, or the vibration of the ground caused by crashing ocean waves, and moved to higher ground.Many people watched the waves approach or went out to explore the beach during a wave trough (receding water).A 10-year old girl is credited with saving about 100 people on a beach in Thailand when she noticed the water receding suddenly and told her mother that it looked like a Tsunami was approaching a lesson that she had recently learned in school.

Earthquake and Tsunami SafetyEarthquake safety Duck and cover.Tsunami safety (when in a coastal, near-sea-level area; two situations, local EQ or distant EQ):If you feel strong shaking for 15+ seconds, after shaking, move to higher ground.If there is a tsunami warning, or if you observe unusual waves (appear to be large and rapid tidal changes, or water recedes), move to higher ground.Do not return until event is over; a tsunami includes multiple waves sometimes separated by 10-30 minutes and may last for hours.

L. Braile, Purdue University braile@purdue.edu, www.eas.purdue.edu/~braileSeismic/Eruption Program (Windows; FREE): http://www.geol.binghamton.edu/faculty/jones/ Tsunami Videos:http://www.asiantsunamivideos.com/Digital Globe images:http://www.digitalglobe.com/Animations: http://staff.aist.go.jp/kenji.satake/animation.gifhttp://www.pmel.noaa.gov/tsunami/Mov/TITOV-INDO2004.movhttp://es.ucsc.edu/~ward/indo.movTsunami database search:http://tsun.sscc.ru/HTDBPacNew/page.asp

7. the growth of population and building in hazardous, low-elevation coastal areasGlobal population map

Close-up of Global population map

Global seismic hazard map

Close-up of Global seismic hazard map

Files needed:NOAA animation: TITOV-INDO2004[1].movS. Ward Animation:indo[1]Ward.movVideos:See: http://www.asiantsunamivideos.com/

December 26, 2004

Great subductionthrust fault earthquake

Largest historical natural disastersThe same geologic processes that make our planet habitable also make it dangerousSeth Stein, Northwestern Univ.