At 3:06 pm, on November 13, 1985, Nevado del Ruiz began to erupt, ejecting dacitic tephra more than into the atmosphere. The total mass of the erupted material (including magma) was 35 million tonnes—only 3% of the amount that erupted from Mount St. Helens in 1980. The eruption reached a value of 3 on the Volcanic Explosivity Index. The mass of the ejected sulfur dioxide was about 700,000 tonnes, or about 2% of the mass of the erupted solid material, making the eruption atypically sulfur-rich.