There appear to have been Rotoiti eruptive vents at the eastern end of the lake and although these are part of the Ōkataina Volcanic Centre they are now believed to be in an area of collapse subsidence outside the north western margins of the Ōkataina Caldera.
It appears that there were Rotoiti explosive vents at the eastern end of the lake, which are now thought to be located outside the northwestern limits of the Ōkataina Volcanic Centre due to subsidence collapse.