In 1027 Yamato said that Onigashima started to crumble.
Before that and at the start of the chapter the island was fine
In fact we didn't have any collapsing signs before this panel. Even when Kaido finished to fight Luffy and got a scar from Kaido.
After that he got some time to recover (he recover fast) until Yamato came.
Between those two panels we didn't see Kaido taking blows.
However his reaction is mysterious he had Luffy in front of him but went to kill Momonosuke.
Kaido probably knows that he can't fight Luffy when he go himself at full power and control his flame clouds.
Hence Momonosuke will probably be able to stop Onigashima.
Kaido going at 100% against Luffy is the trigger for the Island collapsing.
It wouldn't make sense that the collapse start only at some point if it was only because of damages.
Moreover if it was only because of damages Momonosuke should wait when Kaido's health will be close to 0 and gather all the flame clouds.
Before that and at the start of the chapter the island was fine
After that he got some time to recover (he recover fast) until Yamato came.
Between those two panels we didn't see Kaido taking blows.
However his reaction is mysterious he had Luffy in front of him but went to kill Momonosuke.
Kaido probably knows that he can't fight Luffy when he go himself at full power and control his flame clouds.
Hence Momonosuke will probably be able to stop Onigashima.
Kaido going at 100% against Luffy is the trigger for the Island collapsing.
It wouldn't make sense that the collapse start only at some point if it was only because of damages.
Moreover if it was only because of damages Momonosuke should wait when Kaido's health will be close to 0 and gather all the flame clouds.