Energetics of the superflare from SGR1806-20 an a possible associated gravitational wave burst

We discuss in this Letter the energetics of large gamma-ray superflares observed from Soft-Gamma Repeater sources. The last recorded event has in fact ruled out some models for the energy release. For the first time actual information about a possible associated gravitational wave emission may be gathered from the LIGO data, even in the case that most of the energy was emitted in gamma-rays. Even upper limits on the amplitude of the latter $h$ at the expected frequency $f_{c} \leq 2 kHz$ may be useful to further constrain the remaining mechanisms