|
|
Photo of Ruapehu Crater Lake, copyrighted by Robert Decker.
For excellent summaries of Ruapehu and its 1995 eruption click here and here .
Since:
Since the activity in 1995, the volcano has quieted down and the only threat
is to people in the immediate vicinity of the summit. The nearest large town
is Taupo, with a population that probably varies between 20,000 and 60,000
depending on whether it is summer or winter. Taupo is ~100 km NE of Ruapehu.
Other smaller but closer towns are Turangi, Waiouru, Ohakune, and National
Park. Even tinier places are Whakapapa, Iwikau, Tukino, and Turoa Villages,
all within~10 km of the summit.
As far as I know there hasn't been any damage from the 1995 eruption other than the minor inconvenience of slight dustings of ash. There have also been the inconvenience to lots of skiers hoping to enjoy the last month of ski season and being kept off the slopes. The first day of the eruption 4 volcanologists were injured in a plane crash. Two received only minor scrapes and bruises but the other two were more seriously hurt and are still recovering. I have forwarded your question to a friend who is working at the volcano observatory there and hopefully she can provide some more answers.
The current research involves studying both the activity that led up to the 1995 eruption and the activity during the most recent eruption. The former is an attempt to try and understand what the precursors were and can the be better identified prior to the next eruption. The latter is to try and understand the mechanisms of explosions, ashfall, and lahar generation and emplacement.
Scott Rowland
History
Ruapehu has had 50 historic eruptions, more than any other crater lake in the
world. Most of these eruptions have been phreatic. The last major eruption was
in March of 1992. In this century the longest period of repose between
eruptions at Ruapehu has been 12 years (1906-1908). The average period of
repose was about 4 years.
Eruptions at Mount Ruapehu are caused by the interaction of lava and water. Volcanologists call this a phreatic eruption. Because the lava erupts into the bottom of a crater lake, a lot of heat energy converts water to steam. The steam expands violently, throwing water and sometimes ash into the air. The recent increase in activity was caused by a greater volume of lava being erupted into the lake. Similar, but usually smaller, phreatic eruptions have been occurring at Ruapehu since 1889.
Steve Mattox
Source of Information:
Simkin, T., and Siebert, L., 1994, Volcanoes of the world: Geoscience Press,
Tucson, Arizona, 349 p.
For more about Ruapehu click here.
Other Top 101 Categories
VolcanoWorld
More
Questions about Antartica