Friday, December 2, 2011

Avalanche

Two workman alpinists acquire some respect for snow

When it hit, I announced ‘avalanche’ in tones as flat as those of a waiter setting down a mint julep. (“Your snowslide, sir.”) Or so Richard later alleged. I might have said more if the rushing snow hadn't instantly plunged us, face-down, out of control, into its tumbling smother. After surfing for 30 metres or so, we fetched up on the surface. The ride was not uncomfortable, except for the sensation of drowning.

We revisited the scene of this adventure a summer or two later. Pausing on our way up to a climb, we sat in the hut’s shade, sipping our Pocari Sweats, and looked on as Japan's most expensive wall took shape. Every few minutes, the helicopter would stagger in from a nearby rubble field, a boulder swaying from its load sling. Then the pilot would ease his straining craft into a hover and carefully juggle the latest building-block into place.

Cost what it might, the new barrier would come in cheaper than rebuilding the hut. This chalet-like lodge sits at the focus of the Karesawa cirque, right in the centre of the Japan Northern Alps – an insalubrious place to be in mid-winter. More than once, the building has been demolished by avalanches that hit with the force of a shinkansen. Watching the new defences rise higher boulder by boulder, we realised we'd been lucky.

Yet these are far from being the deadliest snowslides in Japan. Top contenders for that title might be the airborne powder chutes that haunt the precipitous Kurobe River gorge. In February 1936, one of these swooped through the darkness onto a construction site at Udo-dani. A 70-ton steel bridge was blown off its supports, landing two hundred metres away.

Two years later, in the early morning of 27 December 1938, a powder avalanche unfurled silently down the steep walls of Shiai-dani, another building site for the Kurobe hydroelectric project. It flattened a four-storey barracks, killing more than eighty workmen in their sleep. Fragments and bodies were hurled up to six hundred metres through the air.

In local dialect, these Kurobe avalanches are called "hou", a name that captures their foam-like character. More air than snow, they blast obstacles rather than bulldoze them – only shattered trees or buildings betray their passing. Eerily little in the way of snowdrifts is left behind.

Many years after the Shiai-dani accident, a group of researchers went back into this valley in mid-winter. Warily, I imagine, they placed instruments in a known avalanche track. From these, the savants deduced that the front of a large "hou" can travel at 200 kilometres an hour, with some internal waves moving at twice that speed. One slide left an icy track behind it, but the snow it piled up below was hardly knee-deep.

If “hou” practise a kind of snow ninjutsu, wet slides are the yokozuna of the avalanche world. Also known as “soko-nadare” (base avalanches), these clear out a snow gully to the ground, ripping out trees and rocks as they pass. A soko-nadare is described by Suzuki Bokushi (1770-1842) in his Snow Country Tales:-

A man from Uonuma set out on an errand on a warm March day and didn’t come back. When his family raised the alarm, the villagers went out to look for him. At a nearby pass, they found a huge wall of snow blocking the road. Perplexed as to where they should start digging, they hesitated until an old man suggested a novel expedient. Taking several younger men with him, he went to the nearest village, borrowed some roosters, and brought them back. Then he scattered feed over the snowbank and let the roosters wander about as they wished, pecking at it. One of the roosters suddenly rose up, stretched its wings, and crowed, whereupon the others all flocked together and began crowing at the same place. The old man turned to the younger men holding shovels and said, “That’s where he is! Start digging!” And everyone dug at once. Digging deeper they suddenly came across a patch of snow dyed red with blood. Digging still deeper, they found the body, with one arm and the head ripped off. Next they found the arm but not the head. Finally, after enlarging the hole and digging here and there in the wall of snow, the head, too, was found. Buried all this time in snow, the poor fellow looked as if alive. At this sight, the wife, who had been standing nearby with her children the whole time, grasped her husband’s severed head and held it in her arms, while the children threw themselves over their father’s body, crying and lamenting. (Summarised from Snow Country Tales.)

Uonuma, in today’s Niigata prefecture, is on the Japan Sea Coast. This is – or used to be – one of the snowiest regions in the world. Every winter, from December onwards, the low-pressure zones come trucking in from arctic Siberia. After soaking up moisture from the sea, they dump it in massive snowdrifts on the mountainsides. Accumulations of up to twelve metres have been recorded on Tateyama, a nearby Meizan.

In the mountains of Echigo, spring avalanches gouge deep furrows that show up on aerial photos as comb-like patterns streaming out leewards from the ridgelines. One June, we went to inspect a snow-gully in this region. After an all-night drive from Tokyo, we ported our skis through a beechwood, with the tips catching on every branch. Coming out from under the forest canopy, we stepped onto the snow and snapped our boots into the bindings. Grey and hard as cement, the snow was pitted with sun-cups filled with grit and leafmould.


Higher up, we had to weave our way between boulders and torn-off tree-branches. This had clearly been a lively place during the spring snowmelt. And even now, living up to its name of Ishikurobi-sawa (Stone Tumbling Gully), it tossed a few boulders down at us as the afternoon sun started to warm the upper slopes.


Reaching the summit over a last snow-stripe, we looked out over the rolling peaks of the Iide massif. From here, we could see that the ridge-tops bounding our gully were sharp-edged and ragged. This too is the work of the avalanches that scour down them in spring, says Koaze Takashi, a geographer. By contrast, the ridges on the Pacific side of Japan are rounded and easier to travel.


Snow shapes these mountains. It carves out distinctive, straight-sided avalanche troughs on steep faces – as seen on Echigo-Komagatake (below) – and it leaves strange hollows in the ground that even the academicians find difficult to explain. Snow also dictates what plants can grow and where – creeping pine on wind-blasted ridges, the rowan (nanakamado) in the sheltered zone under cornices.

Indeed, snow has taken over where Japan's vanished glaciers left off. Ten thousand years ago, the Great Snow Valley of Shirouma was one of the largest glaciers on Honshu. Even today, the permanent snow lies so deep that its lower layers have compacted into ice. If it flowed, this Daisekkei would still be a glacier. As it is, the avalanches rule. Folk who insist on camping here in winter should sleep with pocket-knife in hand, ready to cut their way out of a buried tent.

Karesawa used to hold a glacier too, though a smaller one than Shirouma’s. By the same token, its avalanches pack that much less punch. After picking ourselves up from the one that hit us that Golden Week, we met with a zone of quicksand powder, so fluffy and bottomless that we had to swim our way across. Not a good place to get buried. Later, we passed by Byōbu, its clifftops lost in cloud, and watched as avalanche after avalanche crashed down its gullies. Already the Northern Alps had instilled in us a deep respect for snow.

References

A study on high-speed avalanches in the Kurobe, by H Shimizu et al (1980).

Snow Country Tales: Life in the other Japan (北越雪譜) by Suzuki Bokushi, translated by Jeffrey Hunter with Rose Lesser (1986).

Geomorphological Features of Avalanche Furrows in Heavy Snow Region in Japan, by T Sekiguchi et al (2005).

Geomorphic processes at a snowpatch hollow on Gassan volcano, northern Japan, by Y Kariya (2002).

Yama wo yomu by T Koaze, Professor of Geography at Meiji University. Black-and-white photo of avalanche gully on Echigo-Komagatake is from this book.

Cautionary tales

Avalanched in the Shirouma Daisekkei by i-cjw

Half-dead in Hakuba: how I survived an avalanche in Japan, by Seth Lightcap

2 comments:

wes said...

once again, your vivid accounts and second-to-none research have left me speechless. I'm so glad you were able to live through the avalanche and hope I never have to experience one firsthand.

Your pictures are breathtaking as usual. Do I see some Iide photos in there?

Project Hyakumeizan said...

Wes: yes, the lower series of photos are Iide, except the lowest (of the avalanche debris) which is in the Hakuba Great Snow Valley. Top picture, with the menacing base avalanche debris, is Tanigawa (of course). Our avalanche was a very small one. But it made for excellent aversion therapy....