Mitchell Grace

Combined Honours - Earth Sciences / Oceanography

The largest earthquakes in the world occur at subduction megathrusts, posing a great hazard to coastal communities. Seismicity in these subduction zones behaves differently along the margin and is in part controlled by faulting of and sedimentation thicknesses on the subducting plate, and by the bathymetry and geometry of the down going portion of the lithosphere. All these factors differ along the strike of the margin resulting in different patterns of seismicity observed regionally. The geometry of the down going plate refers to pre-existing structures such as seamounts and bending faults, caused by the bending of the plate as it plunges under the continental lithosphere. Variations in the faulting and hydration of the outer rise have strong correlations to variations in seismicity at depth, with greater amounts of deformation and hydration leading to earthquakes through dehydration embrittlement or reactivation of faults. Also, more uneven plate surfaces are more likely to form small asperities upon subduction, leading to interplate seismicity. It is therefore of importance to understand the characteristics of the subducting lithosphere to better understand seismic hazards along a subduction thrust.

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Pages: 50
Supervisors: Mladen Nedimovic, Keith Louden