1 The Science behind the Earthquake and Tsunami of Dec. 26, 2004 Rob McCaffrey Rensselaer Polytechnic Institute STANYS Conference Nov. 7, 2005

2 Largest Known Quakes 2005 Nias

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4 Singapore Jakarta Kuala Lumpur 2004 (9.3) 1892 (7.6) 1833 (9) 1866 (8.5) 2005 (8.7) Sumatra Aceh Bock et al., AGU, 2005.

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6 How much did the ground move?

7 The Island of Jawi-jawi off the coast of Sumatra

9 Mw 9.23 Dec 26, 2004 Mw 8.7 Mar 28, 2005 Velocities from Bock et al., AGU, 2005.

10 Bock et al., AGU, 2005.

11 Bock et al., AGU, 2005.

12 Bock et al., AGU, 2005.

13 from surface displacements (40 days later) Slip distribution of Dec 2004 quake from seismic waves Data from Subarya et al., Nature, in press, 2005.

14 Survey mode GPS coseismic displacements – December 26 earthquake Data from Subarya et al., Nature, in press, 2005.

15 All of northern Sumatra moved by about 3 meters or more! Data from Subarya et al., Nature, in press, 2005.

16 At southern end of slip region, lifting and extreme tilting of the island indicates the edge of the slip area is abrupt. Data from Subarya et al., Nature, in press, 2005.

17 NIAS Simeulue 2005 quake mostly deeper and beneath land (Nias) Data from Subarya et al., Nature, in press, 2005.

18 Singapore Jakarta Kuala Lumpur 2004 (9.2) 1833 (9) 1866 (8.5) 2005 (8.7) Sumatra Aceh ? Bock et al., AGU, 2005.

19 Sieh and Natawidjaja, 2000 India Plate Australia Plate Mechanical Barriers to Seismic Rupture

20 Tsunami = “harbor wave”

21 Wave speed proportional to ( g h ) 1/2 (g = gravity, h = wave height) By conservation of energy, wave height proportional to h -1/4 The top of the wave outruns the bottom!

22 Tsunami Animation

23 Pacific Warning System

24 Normal tide gauge record Record with passing tsunami

25 Kashmir earthquake of Oct

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27 US Pacific Northwest Offshore Oregon and Washington there sits a loaded subduction zone similar to the Sumatra subduction zone.

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31 Sumatra fault area superimposed on US Pacific Northwest

32 Lose the seat, move your feet!