Has it been proven that Poseidon was the major god that was worshipped in Thera?

Thera is hypothesized to have been the mythical Atlantis. However, I highly doubt this statement. I was wondering which gods or goddesses where worshipped extensively in this Greek island? I only know that Artemis and Apollo were said to have been born in Thera/Santorini. Are there any worshipping temple for Poseidon in here?