A crater lake on top of Mt. Ruapehu, in New Zealand, that has been slowly rising as snow at the summit melts is starting to leak. The crater lake exists due to a tephra dam that formed during eruptions in 1995 and 1996. The fear is that this leakage can begin to rapidly erode the tephra dam and unleash a dangerous lahar flow down the mountain.
Scientists have noticed that the flow of water from the crater lake has increased the past few days and are concerned that the tephra dam may soon collapse, unleashing a lahar flow larger than one released in 1953 that was responsible for the Tangiwai Railway Disaster.
Interestingly enough, we got to visit this site and discuss those events on our field camp in New Zealand last year, run by Massey University.
Read on below for more.
On the evening of December 24th, 1953, a lahar roared down Mt. Ruapehu and into the Whangaehu River. Just after 10pm, the lahar washed out a railway bridge near the small town of Tangiwai. A few minutes later, an unknowing passenger trail plunged into the river. It ended up being New Zealand’s worst railway disaster.
During our New Zealand field camp stint, we stopped by the site of this disaster to begin our discussions on tephra stratigraphy and some volcanology.
Whangaehu River and the Tangiwai Rail Crossing - Feb. 2nd, 2006
Mt. Ruapehu Tephra
Mt. Ruapehu obscured by clouds.
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2 comments
Thursday, January 4, 2007 at 11:37 pm
Yorrike
I get onto Ruapehu a few times a year for snowboarding. Boarding on an active volcano (10 years since a major eruption), combines my passion for geology with my passion for going fast. Quite the mix : )
The Ruapehu crater lake has been built up and drained, causing lahars, many times. There was a “quite” period through the 1950s, and the lake was used as a hot bathing pool for skiers on what are now the Whakapapa and Turoa ski fields (here’s a pic). The current lake pH is somewhere below 1 and the temperature can reach 70 C (source), which is unfortunate in a way, but impressive in another.
I’m eagerly awaiting the flow to occur, but despite the alarm being falsely set off (article here), I think it’ll be a few more months. Probably about March/April when I’ll be demonstrating on my university’s undergrad volcanology field trip : )
Friday, January 5, 2007 at 12:26 am
Dave Schumaker
Ah thanks for that additional information! When I was reading some of the articles about Ruapehu, there was an interesting note that Ruapehu and the Whangaehu River are the most active lahar fields in the world! Quite impressive.