  When a spinning-down neutron star undergoes a phase transition that produces
quark matter in its core, a Super-Giant Glitch of the order ${\Delta}
\Omega/\Omega\sim 0.3$ occurs on time scales from 0.05 seconds to a few
minutes. The energy released is about $10^{52}$ ergs and can account for Gamma
Ray Bursts at cosmological distances. The estimated burst frequency, $10^{-6}$
per year per galaxy, is in very good agreement with observations. We also
discuss the possibility of distinguishing these even ts from neutron star
mergers by observing the different temporal behavior of gravitational waves.
