Soufrière Hills century in Montserrat. When pyroclastic flows and mudflows began occurring regularly, the capital, Plymouth, was evacuated, and a few weeks later a pyroclastic flow covered the city in several metres of debris. The first phreatic explosion in this new period of activity occurred on 21 August 1995, and such activity lasted for 18 weeks until it caused an andesitic lava dome formation. This was initially confined by a sector-collapse scar. This period lasted for another 60 weeks, after which there were major dome collapses and two periods of explosive volcanic eruptions and fountain-collapse pyroclastic flows. The explosion blanketed Plymouth, away,
São Miguel Island the third volcano on São Miguel, the Água de Pau Volcano started erupting on the western flank of Povoação volcano in two phases. The first phase, composed of the older materials, erupted from lava flows and Trachyte pyroclasts, the secondary phase corresponded to volcanic products that began erupting 400,000 years ago. These latter deposits included pyroclastic, trachyte flows (lava and surges), mud flows and a mixture of basalts. In what would become the western portion of the island a fourth volcano formed: the Sete Cidades Volcano erupted 200,000 years ago and continued to erupt until about 36,000 years ago. Between