Mormon notes that the disciples did as Christ had done, which was to work miracles of healing the sick, raising the dead, and causing the lame to walk and the blind to see. We do not get any description of these events. We don’t get the stories of the disciples going to a people and preaching and then being presented with these opportunities. Mormon is eschewing story-telling for a rapid and condensed version of events. They happened, but it isn’t the story he wants to tell. What is important is the witness of the effect of the gospel and the Savior’s visit on the people.
In addition to healing people, the destruction of the land began to be healed as well. Cities which had been burned were rebuilt. Those cities that were underwater remained underwater, however. That tells us that the rebuilding process was done by humans, and was not a miracle. The people began to do what people do, and rebuilt what they could after the terrible destruction.