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Geophysics seminar: An Yin (UCLA) "Water hammers tremor during plate convergence"

05/07/2019 - 12:00pm
Munk Conference Room
Event Description: 

Talk Abstract:

In this study, I show that rapid (~100 km/h) dip-parallel tremor migration at seismic-aseismic transition depths (15–55 km) of a convergent margin can result from pressure-wave propagation in an anisotropic viscoplastic shear zone. The anisotropy is characterized by slip-parallel conduits in the dip direction composed of high-permeability brittle mafic rocks embedded in low-permeability ductile felsic materials. At the onset of a slow-slip event, the
initial compaction of a mafic conduit causes permeability reduction that in turn leads to partial or complete blockage of flow paths. Due to the water-hammer effect, the sudden blockage of the flow paths can trigger a propagating pressure wave with an elevated pore-fluid pressure, which is capable of initiating a progressive shear failure expressed as migrating tectonic tremors along a high-permeability conduit. For a mafic conduit with a pre-slip static permeability of ~ 10^−13 m^2 and a syn-slip dynamic permeability of 10^−15 m^2, the water-hammer model generates a pressure jump of up to 50 kPa, sufficient to initiate tremors along subduction zones and shear-zone deformation during the same slow-slip event


For more information on this event, contact: 
Ignacio Sepulveda Oyarzun
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