I did the figures based on what it would take to sink an island... For it to sink the way it did, it would take at the very least 112 Megatonnes PSI for Akuma to sink Gokentou all the way to the ocean floor while simultaneously causing volcanic and earthquake activety.
I don't know much about Lobo, but if he fought Supes to an even match, that combined with Superman's punching power twells me that Lobo would survive far worse than even high level Megatonne punches... Supes knocked Lobo into Earth Orbit with an uppercut... and was completely unharmed.