Small-scale convective instability and upper mantle viscosity under California

George Zandt, Charles R. Carrigan

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Thermal calculations and convection analysis, constrained by seismic tomography results, suggest that a small-scale convective instability developed in the upper 200 kilometers of the mantle under California after the upwelling and cooling of asthenosphere into the slab window associated with the formation of the San Andreas transform boundary. The upper bound for the upper mantle viscosity in the slab window, 5 × 1019 pascal seconds, is similar to independent estimates for the asthenosphere beneath young oceanic and tectonically active continental regions. These model calculations suggest that many tectonically active continental regions characterized by low upper mantle seismic velocities may be affected by time-dependent small-scale convection that can generate localized areas of uplift and subsidence.

Original languageEnglish (US)
Pages (from-to)460-463
Number of pages4
Issue number5120
StatePublished - 1993

ASJC Scopus subject areas

  • General


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