[1] After decades of research on continental tectonics, there is still no consensus on the mode of deformation of continents or on the forces that drive their deformation. In Asia the debate opposes edge-driven block models, requiring a strong lithosphere with strain localized on faults, to buoyancy-driven continuous models, requiring a viscous lithosphere with pervasive strain. Discriminating between these models requires continent-wide estimates of lithospheric strain rates. Previous efforts have relied on the resampling of heterogeneous geodetic and Quaternary faulting data sets using interpolation techniques. We present a new velocity field based on the rigorous combination of geodetic solutions with relatively homogeneous station spacing, avoiding techniquedependent biases inherent to interpolation methods. We find (1) unresolvable strain rates (<3 Â 10 9 /yr) over a large part of Asia, with current motions well-described by block or microplate rotations, and (2) internal strain, possibly continuous, limited to high-elevation areas.

[1] To determine crustal motions in and around southern California, we have processed and combined trilateration data collected from 1970 to 1992, VLBI data from 1979 to 1992, and GPS data from 1986 to 2004: a long temporal coverage required in part by the occurrence of several large earthquakes in this region. From a series of solutions for station positions, we have estimated interseismic velocities, coseismic displacements, and postseismic motions. Within the region from 31°N to 38°N. and east to 114°W, the final product includes estimated horizontal velocities for 1009 GPS, 190 trilateration, and 16 VLBI points, with ties between some of these used to stabilize the solution. All motions are relative to the Stable North American Reference Frame (SNARF) as realized through the velocities of 20 GPS stations. This provides a relatively dense set of horizontal velocity estimates, with well-tested errors, for the past quarter century over the plate boundary from 31°N to 36.5°N. These velocities agree well with those from the Plate Boundary Observatory, which apply to a later time period. We also estimated vertical velocities, 533 of which have errors below 2 mm/yr. Most of these velocities are less than 1 mm/yr, but they show 2-4 mm/yr subsidence in the Ventura and Los Angeles basins and in the Salton Trough. Our analysis also included estimates of coseismic and postseismic motions related to the 1992 Landers, 1994 Northridge, 1999 Hector Mine, and 2003 San Simeon earthquakes. Postseismic motions increase logarithmically over time with a time constant of about 10 days, and generally mimic the direction and relative amplitude of the coseismic offsets.

Fault slip rate estimates along the Altyn Tagh and Kunlun strike-slip faults in northern Tibet vary considerably between short-term geodetic and long-term geologic studies.Here we reanalyze and model all global positioning system (GPS) data from northern Tibet to determine if these differences might be explained by previously unmodeled transient processes associated with the earthquake cycle, which can bias slip-rate estimates from geodetic data. We fi nd that these effects cannot reconcile the geodetic data with the lowest bounds on the geologic slip rates along these faults, even in the presence of low (<10 18 Pa s) viscosities within the mid-crust or crust and mantle lithosphere. Surface velocities derived from GPS measurements are best reproduced with models with a high-viscosity (≥10 18 Pa s) middle to lower crust and mantle lithosphere.

Two of us from IUCF have contributed, primarily while on sabbatical leave, to the construction and testing of an 1) "tagging facility" and the study of 1) leptonic decay. We report here preliminary results from experimental efforts to measure the 1) + p+p-branching ratio.The leptonic decay of a neutral pseudoscalar meson of the type Po --, 1+1-is a fourthorder electromagnetic process that transforms quarks into leptons. While permitted within the "standard model" (SM), such decays are strongly suppressed and tightly constrained.