It's been 15 years since I last took a Physics course, but I think it takes thousands or 100s of thousands of years to get heat from seismogenic depths to the surface by conduction. So, even if there was some precursory slip, you would need convection/fluids to get from 10 or more km depth to the surface to get heat there. To get enough to cause a plankton bloom in an ocean would be a very large volume of fluid. It would help to have some evidence of this happening in the claimed cases....Chris