11 June 2008
Deaths and research in landslides
Posted by Dave Petley
Now that the Tangjiashan crisis is over, it is clearly time to move on to other things. I will post
a retrospective on that event when the dust has settled. For now I think we should allow the Chinese to bask in the success of their achievement.
To change the topic, I thought it would be interesting to post an analysis that I did a couple of years ago. The analysis was simple but quite fun – I looked at the landslide fatality database for 2003 and 2004 by calculating the proportion of fatalities by large geographical area. I then looked at the field areas of the research presented in the Springer journal Landslides and in papers presented at a selection of international landslide conferences, and worked out the proportions as per the fatalities.
Now ideally there should be some relationship between the locations of landslide deaths and the locations of landslide research, one would hope. Care is needed as:
1. One year of landslide data might not be representative; and
2. The sample of the areas of research might not be representative.
However, the plot does show how far we are from an equitable situation:
In my simplistic world I would hope that most areas plot close to the central line on the graph. In most cases this is clearly not so. The regions with really serious landslide problems in this period – Central America, SE. Asia and S. Asia has a tiny proportion of the research. Regions that dominated the research into landslides – North America and Europe – had very few landslide fatalities. Only East Asia looks to be in the right place amongst those regions with large numbers of both research projects and fatalities.
Two things emerge:
1. Care is needed because in 2004 landslides in Haiti caused huge problems, which mean that for this period Central America dominates the statistics. If we were to take the period 2002-2006 East and South Asia would dominate the fatality count.
2. Only E. Asia appears to have the balance right between research and fatalities. This reflects the large landslide programmes in China, Japan, Hong Kong and Taiwan.
Of course the picture might look different if this were to be examined through the lens of economic losses rather than fatalities, but not I suspect if we were to normalise by GDP or per capita income. All of which serves to highlight the fact that the landslide research community should shift its focus if it really wants to make a difference by saving lives.
I will try to do a better analysis of the full dataset over the summer, but thought it would be interesting to share this initial analysis.
Dave,The research idicators are pretty clear and a good follow-up to the Tangjiashan Lake coverage.There have been many similar disasters that get almost no coverage:June 2000, a sudden flood in Arunachal Pradesh destroyed every bridge and village in its path. Satellite photos showed that a major landslide in Tibet blocked a tributary of the Brahmaputra. The subsequent bursting of the landslide-induced dam unleashed the flood. This is not uncommon in the Himalayas. In the 1970s, a landslide in the upper Ganga created a temporary dam, which then burst and flooded Rishikesh and Hardwar. The massive 1950 Assam quake caused an entire hill, around 100m high, to slide into the Brahmaputra. When this mud dam finally burst, it caused terrible havoc in the valley below. Vinod Gaur, former director of the National Geophysical Research Institute (India), has written about the 1819 quake in Gujarat which created a huge natural bund (Allah Bund) as well as a natural dam 6.5 metres high. Research may not help solve the problem of how to drain such a lake safely since this is always likely to require site speciifc soloutions that, due to the urgency of the response, may seem to be gung ho. But a better understanding of the risks and frequency of these events may influence planning decisions.Thanks for the blog.Harry. (with help from The Times of India)
Dave, you’ve written about the Hattian Bala landslide after the 2005 Kashmir earthquake and the quake lake associated with that. http://www.landslidecentre.org/Papers/engineering_geology.pdfand there’s more information herehttp://www.gsp.gov.pk/but really there’s not a lot more information, not in the exhaustive, thorough way that Xinhua sent news out.but there’s nothing like “news” to follow –
Harry,Yes you are quite right that landslide dams are not uncommon and are poorly reported in general. One of the lessons of the Wenchuan earthquake is that a higher level of preparedness is needed for the long overdue earthquake in northern India / Nepal. Such an event would probably induce valley-blocking slides. Given the massive population on the northern part of the Terai plain, this would be a real threat. I wonder whether countries like Nepal would be able to respond in the way that China has?Edward – Hattian Bala was a big concern, but Pakistan had two advantages over China. The first was that the dam was very high and on a smaller river, meaning that filling was slow, so they had more time. The second was that the earthquake occurred in October, months before the rainy season. A spillway was built in the end and has to date successfully managed the flow. I haven’t been back for a while now so cannot really say how it is doing. Kashmir has not had a really wet monsoon since the earthquake, so the general threat of landslides there remains quite high. The Pakistan givernment have done well in managing the hazard to date.
Does your literature search include non-english literature?