According to Izumo-no-kuni Fudoki, Susano-o-no-mikoto said “Although this land is small it is a nice place. I shall give my name to the land rather than to a stone or a tree.”
Then he created Oosusada (Greater Susa - the Shrine area) and Osusada (Lesser Susa) to rest his spirit.
Susa Jinja is the most important shrine dedicated to Susano-o’s spirit and his name.