  We consider two issues related to the 2011 Tohoku mega-earthquake: (1) what
is the repeat time for the largest earthquakes in this area, and (2) what are
the possibilities of numerical short-term forecasts during the 2011 earthquake
sequence in the Tohoku area. Starting in 1999 we have carried out long- and
short-term forecasts for Japan and the surrounding areas using the GCMT
catalog. The forecasts predict the earthquake rate per area, time, magnitude
unit and earthquake focal mechanisms. Long-term forecasts indicate that the
repeat time for the m9 earthquake in the Tohoku area is of the order of 350
years. We have archived several forecasts made before and after the Tohoku
earthquake. The long-term rate estimates indicate that, as expected, the
forecasted rate changed only by a few percent after the Tohoku earthquake,
whereas due to the foreshocks, the short-term rate increased by a factor of
more than 100 before the mainshock event as compared to the long-term rate.
After the Tohoku mega-earthquake the rate increased by a factor of more than
1000. These results suggest that an operational earthquake forecasting strategy
needs to be developed to take the increase of the short-term rates into
account.
