Post on 15-Jan-2016
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transcript
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The Science behind the Earthquake and Tsunami of
Dec. 26, 2004
Rob McCaffrey
Rensselaer Polytechnic Institute
STANYS Conference Nov. 7, 2005
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Largest Known Quakes
2005 Nias
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Singapore
Jakarta
Kuala Lumpur2004 (9.3)
1892 (7.6)
1833 (9)
1866 (8.5)
2005 (8.7)Sumatra
Aceh
Bock et al., AGU, 2005.
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How much did the ground move?
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The Island of Jawi-jawi off thecoast of Sumatra
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1989
2005
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Mw 9.23 Dec 26, 2004
Mw 8.7 Mar 28, 2005
Velocities from 1991-2004
Bock et al., AGU, 2005.
10Bock et al., AGU, 2005.
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Bock et al., AGU, 2005.
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Bock et al., AGU, 2005.
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from surface displacements (40 days later)
Slip distribution of Dec 2004 quake from seismic waves
Data from Subarya et al., Nature, in press, 2005.
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Survey mode GPS coseismic displacements – December 26 earthquake
Data from Subarya et al., Nature, in press, 2005.
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All of northernSumatra moved by about 3 meters or more!
Data from Subarya et al., Nature, in press, 2005.
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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.
17NIAS
NIASSimeulue
Simeulue2005 quake mostly deeper and beneath land (Nias)
Data from Subarya et al., Nature, in press, 2005.
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Singapore
Jakarta
Kuala Lumpur2004 (9.2)
1833 (9)
1866 (8.5)2005 (8.7)
Sumatra
Aceh
?
Bock et al., AGU, 2005.
19Sieh and Natawidjaja, 2000
India Plate
Australia Plate
Mechanical Barriers to Seismic Rupture
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Tsunami = “harbor wave”
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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!
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Tsunami Animation
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Pacific Warning System
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Normal tide gauge record
Record with passing tsunami
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Kashmir earthquake of Oct 8 2005
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US Pacific Northwest
Offshore Oregon and Washington there sits a loaded subduction zone similar to the Sumatra subduction zone.
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Sumatra fault area superimposed on US Pacific Northwest
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Lose the seat, move your feet!