[IRIS] AGU Session T18: Seismogenesis and Tsunami Hazards of "Aseismic" Island Arcs

[IRIS]

Dear Colleagues,

We would like to draw your attention to the following special session  
at this fall's AGU:

T18: Seismogenesis and Tsunami Hazards of "Aseismic" Island Arcs

Sponsor: Tectonophysics
Cosponsors: Geodesy, Ocean Sciences, Seismology, Public Affairs

Description:
The 2004 Sumatra-Andaman Earthquake (SAE) and Indian Ocean Tsunami  
have led to greatly increased concern about tsunami hazards  
worldwide. The tectonic environment of the Nicobar and Andaman  
Islands section of the SAE rupture zone is not typical of subduction  
zones that experience giant earthquakes, and yet it experienced slip  
equivalent to an earthquake of magnitude 9 or greater. Our inability  
to explain why this segment experienced such large-scale rupture  
prompts us to reconsider whether the Chilean-Mariana paradigm for  
seismic vs. aseismic subduction is adequate for underpinning  
assessments of tsunami hazard in island arcs and ocean basins  
bordered by them. Subduction systems traditionally considered  
"decoupled" or "aseismic" because they lack Mw > 8 shallow thrust  
earthquakes, such as the Tonga-Kermadec and Mariana regions, comprise  
a large portion of the Western Pacific rim. How do we know which  
island arcs are really aseismic? Can we guarantee that these  
‘aseismic’ subduction zones do not experience large earthquakes with  
recurrence times much longer than the historical record? What are the  
importance of various factors such as extensional tectonic stresses,  
forearc deformation, and serpentinization on the seismogenic  
characteristics of these zones? How can we improve our knowledge of  
seismogenisis in island arcs so that we can answer such questions  
with confidence? This session aims at assessing the current state of  
knowledge of seismogenesis and tsunami hazards in island arcs,  
especially those in tectonic environments that are thought to not  
favour the occurrence of giant earthquakes. We invite contributions  
on subduction zone earthquakes, subduction dynamics, island arc  
tectonics, coastal geomorphology and observational seismology and  
geodesy which might help answer the questions posed above. We  
particularly invite studies addressing the characteristics and  
implications of the May 3, 2006 Mw 7.9 Tonga earthquake, which is the  
largest shallow compressional earthquake ever documented in the Tonga- 
Kermadec system. We also welcome contributions addressing how such  
fundamental science can be linked to public on tsunami hazard and the  
protection of vulnerable coastal communities.


Organizers:

Phil R. Cummins
Geoscience Australia
Box 378
Canberra, ACT, AUS  2601
61-2-6249-9632
phil.cummins at ga.gov.au

Douglas Wiens
Washington University
Department of Earth and Planetary Sciences
   Washington University
   1 Brookings Drive
St. Louis, MO, USA  63130-4899
(314) 935-6517
doug at wustl.edu

Mike Bevis
Ohio State University
Civil & Environmental Engineering & Geodetic Science
   470 Hitchcock Hall
   2070 Neil Avenue
Columbus, OH, USA  43210
(614)247-5071
mbevis at osu.edu
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