Walking amongst mountains so majestic on a clear day is awe-inspiring. Today we are safe. Yet on 19th February 1975 Park Ranger Herb Spannagl and a guided school group would have thought that they were safe too.
“The jagged rough-looking lava is known as a’a (a Polynesian word pronounced ‘ah ah’). It was once a slow-moving blocky mass. But pyroclastic flows are hot, fast and dangerous; a mixture of hot volcanic gas, ash and rock that moves rapidly down the sides of the volcano. Temperature typically is 8000C.
Herb Spannagl and the school group were halfway up Red Crater ridge when suddenly there was a loud noise followed by a huge cloud of dust and rocks (pyroclastic flow) hurtling down the north slope towards the spot of South Crater they had left twenty minutes earlier. Eruption after eruption sent hot waves of material down the mountain. Each took about one minute to descend – an average speed of 80 kms/hour.
Then the volcano started getting even more active and, when the wind changed, rocks started falling near the group. Some exploded on landing – firing sharp fragments in all directions. They couldn’t return the way they had come, so Herb hurried everyone up toward Red Crater. They had made it to Central Crater, about 3.7 kms from the crater of Ngāuruhoe, when a blast from a huge eruption blew them all off their feet.
Fortunately, no-one was hurt; but none of them would ever forget that eventful day.”