  We show that cavitation of a solution of thorium-228 in water induces its
transformation at a rate 10000 times faster than the natural radioactive decay
would do. This result agrees with the alteration of the secular equilibrium of
thorium-234 obtained by a Russian team via explosion of titanium foils in water
and solutions. These evidences further support some preliminary clues for the
possibility of piezonuclear reactions (namely nuclear reactions induced by
pressure waves) obtained in the last ten years.
