Ngaruhoe has erupted at
least every nine years, although at the
time of writing the last eruption was in
1975. the impact that it had on the area was that nobody could go around the mountain and tourist couldn't go and take photos incase it erupted again.
This time in history Mt toNGARIRO ERUPTED 70 TIMES BETWEEN THIS TIME FRAME. IT THROW 50 MM OF ASH ONTO THE DESERT ROAD AND IT THROUGH ASH WAY OUT TO NAPIER!!!