T waves generated by the deep "detached" earthquake under Sakhalin, 12 May 1990. Note that the T-wave train consists of two puffs of energy interpreted as conversions from, respectively, P and S waves. That the latter can propagate 1000 km from the hypocenter to the conversion point without losing their high frequencies (necessary to penetrate the SOFAR channel) to anelastic attenuation, requires a continuous, low-attenuating, and hence cold, path: the slab must be mechanically continuous despite the absence of continuous Benioff seismicity.

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