Ruapehu, in New Zealand, is starting to show signs it may erupt in the near future. It is a fairly active volcano, last erupting in Septemeber of 2007, but it is also a rather hazardous volcano thanks to the crater lake at the top that could be breached. Combined with the development on the volcano, it is a potent mix.
Now, why would you ever think to develop on an active volcano? Well, good question! There are ski areas on Ruapehu that are built on some of the lahar (volcanic mudflow) deposits on the side of the volcano and some of these lahars are not that old at all, so the likelihood that a new lahar will take out parts of these ski areas are pretty high. Then again, I never put anything past skiers when it comes to doing dumb things for their sport.
Currently, Ruapehu appears to be releasing a lot more volcano gasses – to the point that they are affecting people near the summit while the temperature of the volcano is rising as well. Most of the recent eruptions at Ruapehu have been phreatomagmatic – in other words, magma interacting with water – and relatively minor, all in the VEI 1 range.
While no one knows that the volcano definitely will erupt, it is making enough noise for the government of New Zealand to issue a warning.