Archive for June 2012

Alaska – The Valley of Ten Thousand Smokes (Part 1)   2 comments

Exactly 100 years after the start of the largest eruption of the 20th century I walked into the site of the eruption – The Valley of Ten Thousand Smokes. Had I been there a century earlier I would have been walking into the Valley of Death. So let me tell you a little of why I was there and what I did.

Float plane. The fun and exciting way to arrive at Brooks Camp.

I was participating on an international volcanological field camp that takes place annually, led by John Eichelberger (in charge of USGS volcanic hazards program) and Pavel Izbekov (a perpetually smiling volcanologist originally from Russia who does some crazy stuff on active volcanoes).

So the start of the trip involved a float plane ride from King Salmon to Brooks Camp on the edge of the great Katmai wilderness. This was my first trip in a float plane and it was exciting. For any aircraft geeks I went out in a Beaver and came back in an Otter (classic De Havilland aircraft). A story is told of a pilot who when he first landed at King Salmon thought how friendly the locals were as they were all waving at him. When he opened the plane door and the bugs attacked he realised why they were waving. Yes, the bugs are plentiful and aggressive and they acquired a real taste for Scottish skin.

Tundra – an undernourished young female brown bear.

At Brooks Camp there are cabins and bears. In fact the bears often wander between the cabins, and when I was there we were told to be a little extra careful as the girlfriend of a mating pair kept hiding from her mate, and so the large boyfriend was often found wandering around the cabins disconsolately looking for her. It was early in the season (i.e. the salmon runs that attract all the bears had not yet started), so I only got a good view of one rather underfed-looking female. The park rangers have been told not to give names to bears (avoids anthropomorphising them apparently), so I was told this was bear 130. And quietly in my ear the doe-eyed female ranger whispered “we call her Tundra, but don’t tell anyone”. Despite the abundance of bears and their close proximity to humans there has never been a bear attack. We did of course get taken straight to a bear briefing the second we got off the float plane, and had to pass a quiz to get a badge and be allowed out. Perhaps a good example of the power of education combined with such a place tending to attract those who have a respect for wildlife and the wild places? But I digress.

First glimpse of the pyroclastic flow deposits (basically an ignimbrite sheet) from the bus journey in. The distal ends of The Valley of Ten Thousand Smokes appears as the pale brown material entering right of centre.

After a bus ride to the trailhead, we started our hike into The Valley of Ten Thousand Smokes (VTTS for short). It was going to be 9 miles and c.2000 feet of ascent, and it usually takes around 8 hours. But this part of Alaska had received what locals call their ‘hundred year snowstorm’ and this dumped a huge amount of snow late in the season. The effects of this we were to discover on the hike in to our base  – the Baked Mountain huts.

After crossing Windy Creek. Edge of pyroclastic flow and fall deposits in the Valley of Ten Thousand Smokes.

It had been a while since I had carried a heavy pack carrying all my field gear and food for 12 days, and the scales at Brooks Lodge told me that I was lumping 83 pounds on my back. There were many times on the walk that I wish I’d left the whisky behind, as this would have saved 3 pounds in weight. The day started warm and sunny, and most of us were in shorts, which was just as well as a fast-flowing creek had to be crossed (in sandals), and the lighter participants helped across. In fact one had to be held between two of us and apparently she moved like a cat-flap. Further up the valley we stopped a few times for geological stuff and spotted a sow and two bear cubs, who scarpered after a long look at the group.

Then it got cloudy and a bit colder. And we had some difficulty negotiating gullies filled with snow. From then on we were on snow most of the time, which was a bit slushy but only knee-deep in parts. Then, with two-thirds of the hike done, the trail turned into a real scorpion. The innocuous flat-lying snowy wasteland that separated us from the slopes to Baked Mountain contained two nasty little streams that we just waded across (knee deep) as boots were already soaked. But they were pleasant compared to the nightmarish plugging through mostly thigh-deep slush, which sapped strength and chilled us to the bone. Many of us who fell over had to slip off our packs, crawl till we could stand again, then lift the dripping packs back onto our backs (often with help from others) and continue. To everyone’s credit they kept going towards the huts and safety and warmth. Eventually we all made it, with some participants close to or at the limits of their endurance. There were some helpful heroics from volunteers who went back down the hill to help those who were struggling – real teamwork. It had taken around 12 hours to walk 9 miles, with the last 3 miles taking almost half of that time. One of the toughest walk-ins I have done in my career. Sorry – no photos of the epic part of this hike – all energy was saved for walking!

[Reflective note: I would not wish the above account to put anyone off participating in the future on such an amazing trip, so I’d like to stress that even though these were unusual thick-snow conditions, safety was taken care off. For example there were radios distributed throughout the group (which were used extensively during the walk-in), and had there been a problem tents would have been erected (we had three with us) on one of the solid ground refuges and stoves fired up to cook food and replenish energy, and also to provide warmth.]

The Baked Mountain Huts. Water from melted snow. Structure on the right is the ‘outhouse’ or ‘rest-room’ in US parlance. It’s of the long-drop non-flushing variety.

The Baked Mountain huts comprise a hut for 6 (which is leaky and mouldy) and a ‘VIP’ hut for 4 to which I was invited. But when I discovered that one of the VIPs was a legendary snorer I decided to look elsewhere.  So I cleared a space in the floor of the storage hut used by the tent people, which I had to vacate early every morning, thus depriving me of my usual slothful enterprises whilst in the field.

On the slopes of Baked Mountain, examining pumice from the 1912 eruption that forms a thick blanket over the mountain. The Valley of Ten Thousand Smokes is behind, which now forms a flat-lying plain (incised in places) of pyroclastic flow and fall deposits, which reach up to 300 m in thickness.

So that’s the lengthy preamble – now for the spectacular scenery and geology.

Griggs Volcano above the clouds as we descended below the clouds, from high on Trident Volcano.

Right across from the Baked Mountain huts is Griggs Volcano, which has a number of young (Holocene) lava flows but no recent/recorded eruption. It looks rather fresh in parts, so is just sleeping. And from the top of Baked Mountain the snow-clad volcanoes of Magiek and Martin can be seen. These volcanoes (and others which come later) are part of the Katmai Cluster, which is a quirky group of volcanoes for which there is no good explanation (in my view) for the ‘clustering’.

Magiek Volcano. (Martin Volcano is hidden behind it.)

Magiek Volcano from Baked Mountain, with Martin Volcano just visible behind it.

But the real enigmatic part of this cluster is also the most dramatic, and its existence produced the VTTS. The small c.500 m diameter rhyolite dome of Novarupta looks innocuous, but it was the final act of a c.60 hour (3-day) eruption that was the largest of the 20th century. The dome occupies a backfilled larger vent structure which was about 3 km by 2 km in size (a very reasonable interpretation). From this vent, in 1912, roared 13 cubic kilometres of magma. That’s actual magma by the way, not the total volume of ash, pumice etc, which was much larger.

Katmai Volcano (left, arrowed) and Novarupta rhyolite dome (right, arrowed). Some 10 km apart but considered to be intimately linked during the 1912 eruption of Novarupta.

And I’m going to end Part 1 with a tantalising enigma. Actually there are two. The first is that prior to the 1912 Novarupta eruption there was no indication of a volcano in the vent area. And the second is that during the eruption a substantial mountain at the Katmai Volcano subsided to form a caldera, accompanied by only trivial amounts of magma/heat escaping during caldera formation. The hypothesis is that magma escaped from a holding chamber beneath Katmai Volcano to feed the eruption at Novarupta some 10 km away, and that the void left after magma extraction caused collapse of the Katmai Volcano. It’s a plausible story, but there are problems with it. Wait for Part 2….

Panorama of Katmai Volcano crater lake which is c.4 km in diameter which now contains c.250 m of water, and which occupies the site of what was once two-three peaks rising way above the remaining crater rim. At the time of its formation it was ‘dry’ and there was small dacitic lava dome at the bottom of the caldera, and much steam and phreatic explosions. All quite trivial in comparison to the huge energy involved in collapsing a mountain.

Posted June 23, 2012 by davemcgarvie in Uncategorized