Sir, Tarawa is an atoll, made up of several islands. Most of the fighting was on Betio; after the fight, U.S. facilities were built on Betio and also some of the other islands, including Bairiki. The sailor in the pic (a SeaBee, perhaps?) is probably on one of the other islands.
As an aside, my wife's father (RIP--he died before Cyndy and I met) was stationed at Tarawa shortly after the place was taken. He got there on or about Christmas 1943. He was a gunner on a B25 and was wounded on a mission to Milli in the Marshalls early in 1944.
Hope this helps, and Semper Fi.
Ron H.