On November 13, 1985, at 9:08 pm, Nevado del Ruiz erupted; ejecting dacitic tephra more than 30 kilometers into the atmosphere. The amount of magma erupted from the volcano was 3% of that from Mount St. Helens in 1980. The eruption reached Volcanic Explosivity Index 3. The material ejected was described by scientists as "unusually rich in sulfur dioxide".