Editing Mount Ruapehu (section)

=== Lahar danger ===
After the 1996 eruption it was recognised that a catastrophic lahar could again occur when Crater Lake burst the volcanic ash dam blocking the lake outlet as it did in 1953. In 1997, the government proposed digging a trench through the blockage in the wall of Crater Lake, but this was plan was opposed by conservation groups and Māori. A [[Ngāti Rangi]] spokesman noted that the mountain was sacred, and said: "as far as we are concerned if these things [lahars] do happen well we step aside. Let them go past".<ref>{{cite news |title=Ruapehu Maori oppose lahar plan |date= 23 October 1998 |work= Evening Post |id={{ProQuest|314621185}}}}</ref>
Other plans considered were building a stop bank on the Desert Road, or creating an early-warning system, which would be much more expensive than digging a trench.<ref>{{cite news |last1=Watkins |first1=Tracy |date= 8 June 2001 |title= DOC drops plans to cut trench on Ruapehu |work= Daily News |id={{ProQuest|315136006}}}}</ref><ref>{{cite news |last1= Wallis | first1 =Anna |date= 13 June 2001 |title= Rift opens over lahar warning system | work=The Evening Standard |id={{ProQuest|314298532}}}}</ref> In 2001, the [[Eastern Ruapehu Lahar Alarm and Warning System]] (ERLAWS) system was installed on the mountain to detect a crater wall collapse and alert the relevant authorities. It began operating in 2002.<ref name=":0">{{cite news |date=10 July 2002 |title=Teething problems delay Ruapehu lahar warning system |work=Dominion Post |id={{ProQuest|337940728}} |quote=The alarm system had been installed in February and successfully commissioned.[...] However, the alarm system would not be 100 per cent till Genesis Power's communications system, which is being used to relay signals from the alarm sensors to the Tokaanu Power Station, was fully operational. The system is being upgraded and is expected to be completed within a month.}}</ref> The lake gradually filled with snowmelt and had reached the level of the hard rock rim by January 2005. The lahar finally occurred on 18 March 2007 (see below).