I usually say nothing if I can't say anything good; however, in this case, I make an exception. A very poor movie; tried and tested story (i.e. unoriginal), every volcanic cliche in the book, no eruptions of brilliance, highly questionable effects and a vast range of technical inconsistencies.
New Zealand never fails to impress by its scenery: pity about some of the actors! The most notable effects were those in the latter part of the movie when memebers of the cast were running to their airlift point (that was strangely devoid of any sign of ash, darkness or other tell-tale signs of volcanic activity): the said effects were strangely reminiscent of those used by Tim the Magician in Monty Python's Holy Gail. Even more surprising was the loss of the top half of the volcano prior to any major eruption occurring.
After this, even 'Volcano' looks polished, professional and credible!