2007 the crossing was called the "Tongariro Crossing", but this was changed to the "Tongariro Alpine Crossing" to emphasize the extreme weather on the exposed terrain. Almost the entire length of the crossing is in volcanic terrain with no vegetation and fully exposed to weather – at moderate altitude. As the crossing is easily accessible, it is walked by large numbers of tourists and casual walkers each year. The Department of Conservation is concerned about trampers being unprepared for the conditions they may encounter and introduced the name change to warn the many poorly equipped visitors of potential hazards. Key hazards are the high wind chill factor, the rapid change in weather and very poor visibility in the sudden storms with blinding snow and cloud. In 2006, two people of an estimated 65,000 walkers died on the track. Although the route is marked with poles, it is quite common in poor weather for visibility to be severely reduced. Poles may be snow covered or destroyed by wind gusts in winter. Volcanic features Most of the walk is through raw volcanic terrain. The three volcanoes in the area are all highly active and the terrain reflects this. Solidified lava flows, loose tephra, and solidified volcanic lava bombs abound. Large amounts of minerals are brought to the surface and are highly visible in the colours of rocks and ridges. Active fumaroles abound on several sections of the walk, constantly emitting steam and sulphur dioxide gas into the air and depositing yellow sulphur specks around their edges. The lakes and pools on the walk are deeply coloured by the volcanic minerals dissolved in them. Some areas feature large springs emitting near-boiling water and torrents of steam. The terrain underfoot for most of the walk is either sharp edged new volcanic rock or loose and shifting tephra, mainly ash and lapilli. In some crater areas it is finer ash that has become moist and compacted. 2012 Tongariro Eruptions from Te Maari Crater In August 2012 a small eruption of 10,000 cubic metres of ash from the Te Maari (sometimes spelled Te Māri or Te Mari) craters on Mt Tongariro sent a shower of ash and blocks up to 1m in diameter over the track. The blocks damaged the roof of the Ketetahi hut which is 1.5 km west of the explosive craters. No one was hurt. The alpine crossing was temporarily closed as about