Contrasting décollement and prism properties over the Sumatra 2004-2005 earthquake rupture boundary.
Styles of subduction zone deformation and earthquake rupture dynamics are strongly linked, jointly influencing hazard potential. Seismic reflection profiles across the trench west of Sumatra, Indonesia, show differences across the boundary between the major 2004 and 2005 plate interface earthquakes, which exhibited contrasting earthquake rupture and tsunami generation. In the southern part of the 2004 rupture, we interpret a negative-polarity sedimentary reflector approximately 500 meters above the subducting oceanic basement as the seaward extension of the plate interface. This predécollement reflector corresponds to unusual prism structure, morphology, and seismogenic behavior that are absent along the 2005 rupture zone. Although margins like the 2004 rupture zone are globally rare, our results suggest that sediment properties influence earthquake rupture, tsunami hazard, and prism development at subducting plate boundaries.
Dean
Simon M
SM
National Oceanography Centre, Southampton, University of Southampton, Southampton SO14 3ZH, UK. smd9@noc.soton.ac.uk
McNeill
Lisa C
LC
Henstock
Timothy J
TJ
Bull
Jonathan M
JM
Gulick
Sean P S
SP
Austin
James A
JA
Bangs
Nathan L B
NL
Djajadihardja
Yusuf S
YS
Permana
Haryadi
H