The central banks have options left that few are talking about but that Berneke has written about in his fed and princeton papers.

One of those is currency depreciation.

http://www.princeton.edu/svensson/pa...

A currency depreciation has proven to be an efective tool for fighting defation in the past. As Bernanke (2002) notes: “A striking example from U.S. history is Franklin Roosevelt’s 40 percent devaluation of the dollar against gold in 1933—34, enforced by a program of gold purchases and domestic money creation. The devaluation and the rapid increase in money supply it permitted ended the U.S. defation remarkably quickly. Indeed, consumer price infation in the U n i t e d
States, year on year, went from -10.3 percent in 1932 to -5.1 percent in 1933 to 3.4 percent in 1934.”

When it comes down to it no option is off the table to stop deflation.

If this is done it will be done as an emergy meassure and there will be no prior warning.