Séminaire ISTerre

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Accommodation of plate motion in an incipient strike-slip system: the Central Walker Lane

jeudi 29 avril 2021 - 11h00

Ian Perce - Seminaire Equipe Cycle
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Geodesy shows that ∼7 mm/yr of dextral shear is accumulating across the Central Walker Lane in the absence of through-going strike-slip faults. To better understand how this shear is accommodated, we describe and quantify the patterns and slip rates of active faults extending between the Lake Tahoe and Walker Lake basins. Lidar data and geomorphic mapping show linear fault traces and stepping fault geometries consistent with the accommodation of dextral oblique-slip motion along the Wassuk and Smith Valley faults, whereas the Mason and Antelope valley faults are primarily dip slip. The remaining unaccounted-for shear is expected to be accommodated by off-fault deformation, including block rotations, broad co-seismic warping, and complex rupture patterns. Recent observations of surface rupturing earthquakes elsewhere in the Walker Lane provide examples of how this deformation is accommodated without being preserved on the landscape. Together faults in the Central Walker Lane form a left-stepping en echelon series of dextral, oblique, and normal faults that extend from south of Walker Lake to north of Lake Tahoe, similar to patterns observed in the initial stages of dextral shear laboratory models. GPS profiles spanning the entire Walker Lane are compared to these new and previously published slip rates, and show that while kinematic efficiency is ~60% and ~90% in the Northern and Southern Walker Lane, respectively, it is only ~25% in the Central Walker Lane.

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Equipe organisatrice : Cycle sismique et déformations transitoires

Séminaire uniquement en visio

Informations de visio :

https://univ-grenoble-alpes-fr.zoom.us/j/91452107048?pwd=N1hLTlB4cTFOa3FKWTl2bCt6U0xVdz09