Where does the gravity go?

Way out of my depth here....but when a supernova pops, how much mass gets converted to energy? 10^51 ergs, do I recall, which is equivalent to 10^30 grams of stuff? Or is a lot of that gravitational potential energy getting converted to neutrinos, etc.?What I'm driving at is, whence come the gravitational waves that we're seeking when a supernova blows? From the "disappearence" of mass or from something more subtle, like what you're suggesting?