Between January and April 1958, new showers of ash and accompanying water vapour (both white and darkened) persisted, and the two "Ilhéus" off the coast of Ponte dos Capelinhos had disappeared under the sand and ash. During this period the cinder cone and isthmus became an integral part of the island of Faial, destroying the roofs of the local buildings and infilling the space to the lighthouse. From May 12–18, 450 seismic events were recorded as the volcano moved into a Strombolian phase, emitting projectiles 500 m into the air, causing moderate explosions and accompanied by infra-sonic waves that shook doors and windows on the island and some adjacent islands. This final phase lasted several months: the last lava currents were visible on 21 October, and the last projectiles were reported on 24 October. During this final stage (around 14 May), fumaroles were discovered inside Faial's caldera, that began emitting sulfurous water vapor, boiling clay and mud.