Another small-scale VEI 1 eruption took place after the central vent exploded from December 19-29, 1969. But two years later from February 3-14, 1971, the towns surrounding Cerro Negro were again evacuated due to the sudden sub-plinian VEI 3 eruption of the summit and the formation and eruption of a new eastern flank. Volcanic bombs were shot approximately 600m into the air, and incandescent gases were released during the time in between eruptions. Ash columns were approximately 10 km high, and a tephra volume of 5.8 x107 m3 (over 300 square kilometers) caused major damage to the local crops and buildings. The city of León alone had recorded 18 cm of ash, which resulted in large-scale building collapse.