Mount Ruapehu Crater Lake and the Coming Lahar of Hot Acid - 2.7.07 (part 1)

[Lane Meyer]

That's February second, not July second. I refuse to give in! Apologies for the quality of these photos...I was toting a point-and-shoot.

This past Wednesday I had the honor and privilege to help scientists from the NZ Institute of Geologic and Nuclear Sciences (where I work) and the Department of Conservation to the summit crater of Ruapehu volcano. Ruapehu, as many of you know, is home to three ski areas, two of which are large and full of some fun terrain when they have snow. Whakapapa and Turoa are two of my favorite places to ski in Aotearoa.


As some of you may also be aware, there is an acidic crater lake at the summit of Ruapehu.

Aerial over view of the volcano's crater in winter:


The lake holds almost several million cubic meters of water, which is about the same as the volume of the Westpac Trust stadium in Wellington.

The water is heated to a comfortable ~27 degrees C (~78 F), and can have a nice Ph of less than 1. To add to it's beauty, there's slicks of liquid sulfur floating on the surface.

My foot for scale, standing on wave-deposited sulfur on the shoreline



The lake fills the bottom of the crater, but at the moment actually lies above the hard-rock rim and is held in place by a dam made of tephra (ash) and loose rubble that was erupted in 1995 and 1996, which is the last time Ruapehu was in action. So all of that hot, acidic, sulfurous water is sitting up there at 2500 meters, being held back by dirt and gravel. Not good. Every day, the lake level rises by around 1 or 2 centimeters. And every day, the water already seeping through the tephra dam eats away a little more at the front and the back.


View of the tephra dam from January 2007:



To make matters more tenuous, at the back of the lake an almost 200 meter tall serac of ice is eroding away steadily, calving huge chunks of ice into the lake. Every time a chuckn falls in, not only does it raise the water level when it melts, it sends seiche (tsunami in a lake) waves across the lake, and erodes the dam a bit more.

The ice wall at the other end of the lake from the tephra dam:

A small seiche wave from a rather large and unsettling collapse while we were there:


Add all this up, and there's a nasty situation brewing atop Ruapehu. A little more water, an earthquake, a huge piece of the glacier calving into he lake, or even a few days' hard rain, and the sucker is going to burst. Luckily, there's not too much in the way downstream, save for a few bridges, railroad tracks, and state highway 1. All of which have been fortified, along with plenty of warning equipment in place.

View of lahar debris from lahars during the 1995-96 eruptions (the 2007 one will come down the valley to the left of the one in this photo that is discolored)

Map schematic of the lahar and the volcano:


What's rad about being a grad student at GNS is that when they are short on personnel, the students get asked to help out. So this past Wednesday, I got the call - they needed an extra set of hands on Ruapehu the next day.

We drove up the night before, and crashed out at the GNS monitoring hut in Whakapapa village.


The next morning, we awoke just before sunrise, and packed our gear up. Here's a shot looking out to the south.


We drove around to Turoa, through Ohakune, the carrot capitol of the Southern Hemisphere, and made out way tot he lower parking lot at Turoa, where they are putting in another ski lift. Which is good for GNS, because there's a guy doing heli-pours of concrete for the lift tower foundations, so he is already up there (= less Hobbs minutes).


Our ride for the day was a Squirrel (the kind with rotors, not the kind from Seattle with skins), which is a pretty powerful chopper.

Funny thing - when I used to work at the USGS, when we'd fly to the lava flows on the Big Island, we had to do and entire days worth of training, and wear all kinds of special gear, and it was very official. Here, you get asked to go, and you get in the chopper. No special bullshit whatsoever.

We took off and hugged the ground up over the terrain of Turoa, and made it over the lip into the crater.



The back serac wall of the lake from above:




Pete the pilot dropped two of us off with all our gear, and went back for the others.

Check out how eroded the dam is now:


We landed (on the tephra dam), unloaded our gear, and had a look. Almost all the snow is gone from the crater, except for the perennial snowfields (one of which had turns on it!) and the top of the Mangatoetoenui glacier.
Turns:


The tephra dam is eroding severely. Check out this photo taken at the beginning of January, in comparison to the one above taken a few weeks ago:

A few weeks ago, a GNS scientist kayaked out a lake-level
probe:


Our goal for the day was to set up a $120,000USD laser scanner, and make a 3D map of the tephra dam. For the tech heads, it scans at a resolution of 200 mm over a distance of 350 meters. I'd like to see your Canon EOS 1-Ds do that Midget! GNS comes up here about once every two weeks to do this, to study how much of the dam erodes until it fails catastrophically and the lahar occurs.

The scary as shit thing here is that if it did go and we were standing on it, we'd have less than a minute to run off and onto high ground. Even worse is if the serac at the back of the lake fails, and a big enough chunk falls in to make a wave that erodes the dam - that would take about 30-45 seconds. The small waves we saw we timed at 35 seconds. About once every five minutes, you would hear a huge CRAAAACK just like a peal of thunder, and you would freeze while your stomach flipped upside down and you listened for the accompanying splash that meant "time to run for your life!"

[Lane Meyer]

Crater lake from the shore in the morning sunlight:


My colleague setting up a remote station:


Measuring the temperature:


One of our three stations:


The other two scientists decide to risk it and climb down into the runnels in the tephra dam to measure the seepage:


Kinda scary when they say to us "we're going down, will you watch the lake and tell us if you hear anything funny."

View across the lake:


What remains of last winter's snow at the bottom of the back of the tephra dam:


We watched this piece of ice fall in, which created some small seiche waves.




Our ride home came just in time, as the clouds started to build around 11:30 am, and we began to worry that we were going to have to walk out with all our heavy and expensive gear


The ride out was amazing. We flew down the Whangaehu river valley (the path of the future lahar), and we flew VERY close to the ground, pretty much right over the waterfall that's just beyond the corner from the tephra dam. I snapped this while hanging out the window of the chopper with my camera pointed back at the end of my outstretched arm, got pretty lucky (and didn't drop my camera!)


A little close to the walls, eh?


Some nice scenics on the way out:



Wouldn't mind skinning up someday to make some turns down that face:


Had to do a bit of cloud dodging and needle threading too:



All in all a sick adventure. We're slated to go back two more times int he next two weeks, I hope I get to go again. I'll post updated pics if I do fly up there again, but in the mean time, watch the news in case it goes.

[brettf]

cool. really cool.

[backpack]

Very nice. It would be cool to have a front row seat for the lahar.

[skiergirl]

Thanks for sharing. Geology trip reports rock! heh heh.

[springsproject]

wow, sciencey. you have a really cool office, awesome pics

[ridefree]

thats pretty damn cool to see. As close as one can be across the globe.

[Son1cdeth]

fuckin coolness Lane. You've got a pretty sweet gig going down there.

[72Twenty]

That kicks ass!

Although, I must say...



In my opinion, this one is still much more impressive as you approach it on I-25...

[Chiz]

very cool. and when it pops, you will be right there

[marmot mb]

Very very cool TR.

That guy in the Kayak is nuts. PH of 1 at 27 C. Insane. Is my ass hot cause the water is warm or is my ass fat melting from the acid.

When that damn goes there will be some serious cool shots to be had.

[guermo]

VERY cool TR lane! You are living a scientists fantasy.....

[G]

Dayam dood. That sounds like a really excellent trip. Thanks for reporting. Now I'm jealous.

Have you left Christchurch for wellie?

[Mofro261]

Can you use this TR for part of you thesis?


That was awesome.

[Schmear]

"The K-12, dude. You make a gnarly run like that and girls will get sterile just looking at you."

Cool photos, Lane. I'd like to have your job for a day.

[Lane Meyer]

I'd like to have your job for a day.

And I yours, my friend.

Thanks for the kudos everyone. Will keep you posted as the story unfolds. Looks good for a return to the crater next week.

[bakers_dozen]

Awesome

Lane whats the deal on your project/school. I'm finishing up my masters in geology here in Calgary and am starting to phd shop for potential projects/schools. Would love to go out to Aus or New Zealand.

[gonzo]

That's not cool at all.


How acidic is 1? Melt your face off? Burn? No fishies?

[HobieTony]

Cool shots, and an awesome gig. I have to wonder though, if you know the dam will bust soon, and the amount of water retained is getting higher all the time, why the fuck dont they just blow it? Evacuate the people that need to be evacuated, and bust the dam under controled circumstances - Like we do for avalanches! Just wonderin...

[lemon boy]

total acidic sweetness Mr. Meyer.

[goldenboy]

That was cool. Thanks for sharing

[smitchell333]

Wow thats going to be cool to see go - as long as you're far enough away.

Next time you should get them to take you up, leave you there for a day and bring your skis for this nice bowl.

[cloudpeak]

Wow! Amazing photos and trip.

[Squirrel99]

did somebody say acid?


Lane, awesome write up.

You've got some cool projects down under and no teaching to boot

[mmmthmtskier]

...just your average TR...