Anharmonic lifetimes tau(a) of fracton modes in percolating elastic ne
tworks with the fourth-order anharmonicity are numerically investigate
d. The results show that the frequency dependence of tau(a) drasticall
y changes at 3 omega(c) where omega(c) is a phonon-fracton crossover f
requency. The physical interpretation for the drastic change of the fr
equency dependence of tau(a) is given.