Historically Tongariro (from current centre of activity Ngauruhoe) and the nearby Ruapehu are the most active in New Zealand. Tongariro last erupted in 1977 in a very small eruption classified as VEI 1 and generally throughout history it has experienced little strong activity above VEI 3, an exception being a VEI 5 event a few thousand years ago. It is highly likely therefore that the current period of inactivity will follow the same trend.
After finding the below video from the recent Eruptions blog post, I thought it would be a nice idea to discuss briefly what is potentially occurring in the conduit for the duration of this video. It is not often that you have videos as good as this (click the read more button on the right!).