The boundary between the lithosphere and asthenosphere is associated with a platewide high-seismic velocity "lid" overlying lowered velocities, consistent with thermal models. Seismic body waves also intermittently detect a sharp velocity reduction at similar depths, the Gutenberg (G) discontinuity, which cannot be explained by temperature alone. We compared an anisotropic tomography model with...

Electrically conductive regions in Earth's mantle have been interpreted to reflect the presence of either silicate melt or water dissolved in olivine. On the basis of laboratory measurements, we show that molten carbonates have electrical conductivities that are three orders of magnitude higher than those of molten silicate and five orders of magnitude higher than those of hydrated olivine. Hig...

Coastal California has evolved through a series of plate tectonic interactions that significantly affected the geologic, thermal, and hydrocarbon maturation histories of the area. Numerical solutions for steady-state heat transfer are used to estimate temperature suppression resulting from plate subduction along coastal California, and to model thermal refraction within the Pismo basin. Numeric...

[1] We have modeled linear viscoelastic relaxation of a uniformviscosity asthenosphere following large earthquakes in the AegeanAnatolian region during the 20th century to evaluate whether this process contributes significantly to the regional velocity field. We address in particular whether southward motion of the Aegean Sea region relative to central Anatolia (and thus extension of western Tu...

The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation of secondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; however, there are no reports that these signals have been used to infer subsurface structure. We use sat...

[1] We present a novel explanation for absolute trench-normal motions of slabs surrounding the Pacific. Rapid subduction-zone retreat on the eastern side of the Pacific and slow advance in the west can result from the large-scale asymmetric plate configuration. We use simple fluid dynamics to explain the mechanical background of this hypothesis, and we use the results of a simple finite differe...

[1] We develop a two-dimensional boundary element earthquake cycle model including deep interseismic creep on vertical strike-slip faults in an elastic lithosphere coupled to a viscoelastic asthenosphere. Uniform slip on the upper part of the fault is prescribed periodically to represent great strike-slip earthquakes. Below the coseismic rupture the fault creeps in response to lithospheric shea...