we think the tremor may be affected by fluids, but if it is, it would be fluids released by the subducting slab at depths of 20-40km. In other words, fluids collected by the crust when it was nearer the surface millions of years ago.

Glacial rebound is occurring, and tremor is occurring, but many places with tremor haven't been recently glaciated, and many places recently glaciated have no tremor, so there is no obvious correlation.