Sinamoi asks you to see if any other survivors need any help. To complete this quest, the side-quests Ashes to Ashes and On the Air need to be completed. See their respective articles for more info on those quests. Other side quests that can be received at this time will not advance the main storyline.
Mike can be found outside the Lifeguard Tower garage, and Dominic is on the top floor to the left of the building Sinamoi is in, at the base of the ladder.