[IRIS] U04: The Indian Ocean Tsunami 2004: Two Years On

[IRIS]

Union Special Session at Fall 2006 AGU Meeting

U04:  The Indian Ocean Tsunami 2004: Two Years On

Almost two years after the Great Earthquake and tsunami of 26th  
December 2004 along the Andaman-Sumatra subduction zone, research  
based on seismology, geodesy, satellite imagery, tsunami modelling,  
and marine geophysical surveying has improved our understanding of  
the catastrophic event as well as the subsequent great earthquake of  
March 2005. The earthquake of December 26th was the one of the  
largest since 1900, and the tsunami the most destructive ever  
recorded. It was the first to be recorded by modern broadband  
seismometry, and dynamic displacements were also measured at GPS  
sites. The tsunami was observed directly by satellite altimetry and  
tide gauges, and other observations from tsunami deposits have been  
made across the affected area. There have been numerous marine  
expeditions exploring the southern section of the earthquake rupture  
zone, acquiring multibeam swath bathymetry, reflection- and  
refraction seismic data and aftershock activity with ocean-bottom- 
seismometer networks, as well as seabed visual imagery. Numerous  
inverse and forward models have investigated the rupture evolution  
and slip distribution in this event. Tsunami wave models have been  
based on various rupture mechanisms, and these in turn have been  
derived from combinations of seismology, GPS geodesy, inverse models  
of the tsunami, and coral reef geodesy. A better understanding of the  
Andaman-Sumatra subduction zone is being applied to hazard assessment  
in other areas such as Cascadia and Japan, even as efforts to  
reconcile these models continue. New tsunami warning systems are  
being installed in the Indian Ocean Basin, both in deep and coastal  
waters. Notwithstanding the new work, and mainly due to uncertainties  
attributable to data limitations, our understanding of the earthquake  
and tsunami is incomplete. Studies on spatial and temporal evolution  
of fault slip indicate interesting - even perplexing - fault rupture  
behaviour. Specific questions include; what are the commonalities and  
differences between proposed rupture models; how well can the  
earthquake source description and resulting seafloor deformation be  
related to genesis of the destructive tsunami; is current theory  
adequate to explain the various seismic, geodetic, tsunami and other  
observations (for example, can afterslip be clearly distinguished  
from asthenosphere relaxation in explaining post seismic  
displacements); is excitation of the tsunami clearly understood; and  
how does the slip evolution and tsunami excitation in this case  
compare with other great subduction earthquakes? Based on the  
enormous amount of new work on the Andaman-Sumatra earthquakes and  
tsunamis, the objective of the session is to bring together  
scientists from all disciplines to present their research in the  
region and to foster and encourage multidisciplinary collaboration.  
Applications of the research in the Indian Ocean to other areas are  
also encouraged.

David R Tappin
British Geological Survey
Kingsley Dunham Centre
Keyworth
Nottingham, GBR  NG12 5GG
44 115 9363449
drta at bgs.ac.uk

Stefan Ladage
Federal Institute for Geosciences and Natural Resources (BGR)
Stilleweg 2
Hannover, DEU  D-30655
+49 (0)511 643 3737
s.ladage at bgr.de

Chris Goldfinger
Oregon State University,
104 Ocean Admin Bldg
Corvallis, OR, 97331-5
USA
(541) 737-5214
gold at coas.oregonstate.edu

Kenneth Hudnut
U. S. Geological Survey
USA
hudnut at usgs.gov

Hiroo Kanamori
California Institute of Technology
USA
hiroo at gps.caltech.edu

Jeffrey Freymueller
University of Alaska, Fairbanks
USA
907-474-7286
jeff at giseis.alaska.edu


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