Article from the December 2006 issue of
Geo-problems of the Central Himalaya
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Unwanted passenger |
As part of my India tour, the National Institute of Technology, Kurukshetra, invited me to participate in a "Natural Hazards" workshop, which included a three-day visit to the Himalayas. The institute is initiating a course in disaster management and the workshop was arranged as a kick-off session to include the students. Our first day was a series of informal discussions on hazards in general and those affecting the Himalaya in particular. Since the 2004 tsunami and the Kashmir earthquake, Indian scientists have become very aware of the country's vulnerability for a variety of natural hazards and the NIT programme is typical of the will to learn more and to convey this knowledge to the next generation of scientists. The institute has a great advantage compared with many similar institutes worldwide — money is no object. The Indian government gives as much as they need, in fact, usually more than they ask for, and foreign groups are a welcome addition. The expenses of our visit and that to the hill station were covered completely, including transport from Delhi, meals and even getting laundry washed and ironed.
The second day was an early start to the state of Himachal Pradesh, where we were lodging for the night in Solan, just south of the Southern Boundary Fault. The Lower Himalaya rises steeply from the plain and the towns and villages seem to be almost suspended on the slopes. The roads are generally good, but clogged with lorries travelling to and from Nepal and all towns between. As an addition to the Holy cows, we now had Barbary Apes to contend with, whole groups on the roads, looking and begging for food. We reached Solan after dark, booked into the lodge and went to eat in a simple restaurant, as guests of a local hydrologist. Next morning we set off before breakfast, although our early morning tea had, as usual, been brought to our bedside at 7.00 am, a reminder of the British in India before independence. No day starts without early morning tea. Our destination was only some 50 km further, but it took over two hours to reach Shimla, capital of Himachal Pradesh and summer capital of the British. We took breakfast somewhere on the mountain road, sitting outside watching the cavalcade of trucks whilst enjoying our chappati and joghurt.
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Shimla: repairs after landslide |
In Shimla we dumped everything at our hostel and set off on foot through the town. This was no building stones walk, but to landslide sites in the town, a major problem for many of the mountain communities. There are two forms of landslide — the one is from land-fill sites, the other from the instability of fractured metamorphic rock, result of brittle deformation. At several places in the centre of this town of 250'000 inhabitants, we discovered landslides that had destroyed part of the main road. No housing has suffered to date, but it is only a matter of time and we noted retaining walls with ominous bulges and trees hanging diagonally over the slopes, a sign of continuous creep of the ground in which they stand. It was also possible to see where slopes had regained stability, as the diagonal trees had started to grow vertically again. The landfill sites are a big problem in hillside towns. Slopes are cleared for construction work and the rubble just dumped to one side. After several years and with no change to local planning laws, something is then constructed on this unconsolidated rubble and slowly the slump begins, another retaining wall is put in place, more rubble dumped, more sliding ad infinitum.
With more geological know-how, the fracture zones are recognised today, but many are already integrated into urban development. Inward dipping fracture zones are less of a problem, in fact, we saw a row of very old buildings built on an inward dipping and stable phyllite outcrop, but the road in front had subsided some 6 feet and because the residents had no rights to continue building steps down to road level, it not being their land, most had makeshift wooden steps that could be removed at night after they shut their shops. The tiling in the gents' toilet under the road (well, you have to observe your geology where it is best presented), showed displacement of some 5 cm. Houses and road are separated by a fault plane!
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Fault in gents' toilet |
Ca. every hundred years a catastrophic landslide can be expected, which could potentially kill thousands of people, but large urban communities cannot be moved, so now the question is how to secure these areas, and that is the main object of study of the local geology experts and engineers. But this problem is not confined to urban regions. On our return journey we made several stops to see large areas of radially-fractured phyllite along the main roads, lifelines of the mountain communities. A catastrophic landslide anywhere along the main arteries would cut the communities off from the outside world on which they depend. We spent three hours that evening discussing the problems informally and, after returning to Kurukshetra, the workshop concluded next day with presentations on geohazards and the way to move forward in planning remediation and risk reduction. It was a very pleasant and professional event and I am most grateful to my hosts for arranging this event as part of my India visit.
Annette
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Last modified on Tuesday, December 12, 2006 at 22:12
