The Science behind the Earthquake and Tsunami of Dec. 26, 2004 Rob McCaffrey Rensselaer Polytechnic Institute STANYS Conference Nov. 7, 2005
Largest Known Quakes 2005 Nias
Kuala Lumpur 2004 (9.3) Aceh Singapore 1892 (7.6) 1866 (8.5) Sumatra 2005 (8.7) Jakarta 1833 (9) Bock et al., AGU, 2005.
The Island of Jawi-jawi off the coast of Sumatra
Velocities from 1991-2004 Mw 9.23 Dec 26, 2004 Mw 8.7 Mar 28, 2005 Bock et al., AGU, 2005.
Slip distribution of Dec 2004 quake from seismic waves from surface displacements (40 days later) Data from Subarya et al., Nature, in press, 2005.
Survey mode GPS coseismic displacements – December 26 earthquake Data from Subarya et al., Nature, in press, 2005.
All of northern Sumatra moved by about 3 meters or more! Data from Subarya et al., Nature, in press, 2005.
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.
Simeulue NIAS 2005 quake mostly deeper and beneath land (Nias) Simeulue NIAS Data from Subarya et al., Nature, in press, 2005.
Kuala Lumpur 2004 (9.2) Aceh Singapore 2005 (8.7) 1866 (8.5) Sumatra Jakarta 1833 (9) ? Bock et al., AGU, 2005.
Mechanical Barriers to Seismic Rupture India Plate Australia Plate Sieh and Natawidjaja, 2000
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!
Normal tide gauge record Record with passing tsunami
US Pacific Northwest Offshore Oregon and Washington there sits a loaded subduction zone similar to the Sumatra subduction zone.
Sumatra fault area superimposed on US Pacific Northwest