Strain modelling, seismic anisotropy and coupling at strike-slip boundaries: applications in New Zealand and the San Andreas fault
Published:January 01, 2004
M. K. Savage, K. M. Fischer, C. E. Hall, 2004. "Strain modelling, seismic anisotropy and coupling at strike-slip boundaries: applications in New Zealand and the San Andreas fault", Vertical Coupling and Decoupling in the Lithosphere, J. Grocott, K. J. W. McCaffrey, G. Taylor, B. Tikoff
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Despite similar surface transform faulting behaviour, observed shear-wave splitting patterns in the California and New Zealand plate boundary regions are markedly different. To better understand the origin of the seismic anisotropy in these regions we model mantle flow and strain for a variety of strike-slip plate boundary scenarios. Simple relations between the flow or strain and elastic anisotropy are assumed to determine the integrated splitting in shear particle motion along teleseismic paths. Strain-controlled models fit the observations in New Zealand and California better than simplified flow-controlled models. Fast shear polarizations are progressively rotated toward the shear plane over time,...
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Vertical Coupling and Decoupling in the Lithosphere
Recent advancements in the understanding of mountain belts have focused on vertical coupling of the lithospheric layers. This volume describes the extent to which observed or inferred sub-horizontal coupling or attachment zones provide vertical kinematic linkage between rheologically distinct layers in the continental lithosphere. A common theme is whether the deformation, which partitioned differently in each layer, is linked kinematically across attachment zones and driven by flow in the deeper crust and mantle lithosphere.
The papers are divided into six sections. The first analyses the extent to which mantle flow controls deformation of the overlying layers. The Vertical axis block rotations section uses geological and palaeomagnetic data to constrain the role and magnitude of basal shear across mid-crustal attachment zones. The Lower crustal flow and topography section addresses the time-dependent development of orogenic plateaux and their role in the orogenic cycle. Multiple examples of the spatial and temporal development of lithospheric coupling are given in both the Orogenic examples and Subduction examples sections. Finally, rheological constraints of vertical coupling in the lithosphere are investigated.