The World Stress Map database contains thousands of intraplate stress indicators, with the potential to provide important constraint for arguments about the relationship between tectonic stresses and both the kinematics and dynamics of plate motion. Previous analysis has emphasized regions of specific interest, relying almost completely on a visual inspection of the data for trends. We present a global statistical analysis of the stress indicators to quantify trends in the data with a wavelength of at least several hundred kilometers. The analysis is performed within 5 x 5 degree bins using the 4503 indicators of sufficient quality to provide reliable information about the tectonic stress field (quality rating of A to C). We analyze two types of information contained within the stress indicator dataset. First, we analyze the spatial distribution of the average stress regime (Normal, Strike-Slip, or Thrust) within the bins. Second, the Rayleigh test, a standard statistical method in the analysis of directional data, is applied to the SHmax orientations within the bins to test the null hypothesis that the orientations are random. These analyzes quantify and extend a number of important conclusions drawn from visual inspection of the World Stress Map, including the existence of broad regions of compression and uniform directional trends throughout much of the continental plate interiors. Trends exist in many regions at a high confidence level (90 and 95%), including eastern North America, western South America, western Europe, and central Asia. Trends tend to be much weaker in the slowest moving continental plates. The oceans show predominantly normal to strike--slip data near ridges, and strike--slip to thrust in old ocean basins. There is a strong correlation between the average SHmax direction in bins which pass the Rayleigh test and both the ridge push torque and the absolute plate velocity azimuths, with more bins (approximately 50% ) being consistent with ridge push torque directions. This provides further evidence to support the conclusion that the intraplate stress field is strongly influenced by the ridge push force.
The SHmax orientations within 5 x 5 degree bins which pass the Rayleigh test, plotted on a base of average topography. Open and solid--filled bars designate bins in which the null hypothesis that the SHmax orientations of the indicators are randomly distributed has been rejected at the 90 and 95% confidence level, respectively. The set of open bars are a subset of the solid--filled bars; that is, each open bar is superimposed on a solid--filled bar. Bin centroids are designated by solid--filled circles.