Earthquake prediction has not had a good record, but it seems
that vastly larger tectonic processes are now becoming the
subject of risk analysis (Nikolaeva, K. et al. 2011. Numerical
analysis of subduction initiation risk along the Atlantic
American passive margins. Geology, v. 39, p. 463-466). The
Swiss, Russian and Portuguese authors focus on the old (Jurassic
~170 Ma) and presumably cold oceanic lithosphere on the western
flank of the Atlantic, against both the North and South American
continents. Increased density with ageing imparts a potential
downwards force, but that has to overcome resistance to plate
failure at passive margins. The dominance of upper continental
lithosphere by rheologically weak quartz tends to make it more
likely to fail than more or less quartz-free oceanic
lithosphere. So, if subduction at a passive continental margin
is to take place, then where and when it begins depends on the
nature of the abutting continental lithosphere. That on the
Atlantic’s western flank varies a lot, r