Earthquake ruptures are complex physical processes that may vary with
the structure and tectonics of the region in which they occur.
Characterizing the factors controlling this variability would provide
fundamental constraints on the physics of earthquakes and faults. We
investigate this by determining finite source properties from second
moments of the stress glut for a global dataset of large strike-slip
earthquakes. Our approach uses a Bayesian inverse formulation with
teleseismic body and surface waves, which yields a low-dimensional
probabilistic description of rupture properties including spatial
extent, directivity, and duration. This technique is useful for
comparing events because it makes only minor geometric constraints,
avoids bias due to rupture velocity parameterization, and yields a full
ensemble of possible solutions given the uncertainties of the data. We
apply this framework to all great strike-slip earthquakes of the past
three decades, and we use the resultant second moments to compare source
quantities like directivity ratio, rectilinearity, stress drop, and
depth extent. We find that most strike-slip earthquakes have a large
component of unilateral directivity, and many of these earthquakes show
a mixture of unilateral and bilateral behavior. We also notice that
oceanic intraplate earthquakes usually rupture a much larger width of
the seismogenic zone than other strike-slip earthquakes, suggesting
these earthquakes consistently breach the expected thermal boundary for
oceanic ruptures. We also use these second moments to resolve nodal
plane ambiguity for the large oceanic intraplate earthquakes and find
that the rupture orientation is usually unaligned with encompassing
fossil fracture zones.