The Willis Research Network - the world's most important hazard and risk collaboration?

Willis is a large insurance and reinsurance broker based in London. A key part of their primary business lies in arranging insurance for catastrophe risk - i.e. losses from mega-events such as an earthquake in Tokyo or San Francisco, a storm surge flood in London or a volcanic eruption near to Mexico City. Calculating the risks associated with these events is a challenging task, but of course the stakes are high as large events can induce catastrophic losses. Parts of the reinsurance industry was badly burnt by Hurricane Katrina for example. So, in order to calculate the risks and potential losses reinsurance companies use Catastrophe Models (usually called Cat Models), which are complex simulations of the impacts of large events. Getting these models to sensibly estimate potential losses is difficult - and of course requires a good knowledge of the science of the hazard in question.

A few years ago Willis approached one of my colleagues, Prof. Stuart Lane, and I to see if we would be interested in joining a research network that Willis would support. The idea was to bring together key parts of the reinsurance industry and top academic researchers on hazards and risk in order to improve the ways in which risk is modelled and handled in the insurance industry. And so the Willis Research Network was born. Initially the network consisted of seven very carefully chosen UK academic institutions - Durham, Bristol, Reading, City, Cambridge, Exeter and Imperial. Membership of the network is by invitation only, and active participation is ensured through the sponsorship by Willis of a research fellow in each institution.

A few years on, and the network is now an extraordinary entity. That initial group of seven has been joined by universities from the USA (e.g. Princeton and NCAR), Japan (e.g. Kyoto), Italy (e.g. Bologna), Germany (e.g. GFZ Potsdam) and Australia (e.g. SEA). I am pretty sure that it is now the largest and most dynamic academic-industrial hazard and risk network in the world, and it is generating some amazing research.

In the last couple of days the network announced associate membership of ten new institutions, including the British Geological Survey, the UK Met Office, The UK National Oceanography Centre, the Ordnance Survey and GNS Science in New Zealand. Research now spans natural perils, visualisation, social dislocation and financial management. I suspect that over the next few years this network will come to dominate research into catastrophic risk management. The publications section is well worth a look, not least because there are some very useful background presentations there from some of the world's top hazards researchers.

Landslides and the UN's Global Assessment Report on Disaster Risk Reduction

The UN ISDR is today launching with a great fanfare the first Global Assessment Report on Disaster Risk Reduction. This report "provides hard-hitting evidence to demonstrate how, where and why disaster risk is increasing globally and presents key findings from a global analysis of disaster risk patterns and trends, including where high mortality and economic loss is concentrated. ." The report is online now and can be downloaded here.

I haven't yet had time to read the whole of the 200 page document - I will do so in due course - but have taken some time this morning to look at the landslide hazard / risk section in Chapter 2n. This was generated by the Norwegian Geotechnical Institute and has been peer reviewed by some eminent people. So how does it look?

I think a good starting point is to say that it has to be recognised that this is a very difficult thing to do. There are all sorts of problems in the collation and analysis of this type of data. However, I also have to say that I have some reservations about the outcomes, which don't to me seem to correspond to what we actually observe.

The landslides section starts with a premise that I find bizarre. The opening sentence is as follows: "Observed mortality in landslides triggered by high precipitation is approximately six times higher than in landslides triggered by earthquakes." Huh? No source or justification is provided for this statement. I just cannot see how it can be justified. In recent years we have large numbers of fatalities from landslides in the Kashmir earthquake and the Wenchuan earthquake, bit of which swamp the fatality signal from rainfall events. Perhaps this study was done before the impact of these events could be included, but there is plenty of documentation of mass fatalities from earthquake-induced landslides even before this event. Perhaps the problem here is that earthquake-induced landslides are included in the earthquake hazard section, but we should be under no illusions that the impact of this is ponce again to greatly under-estimate the risk associated with landslides. This is very frustrating!

The upshot is that the risk model considers only precipitation-induced landslides. We need to keep this is mind when evaluating the study. The headline result of the analysis seems to be (this is a direct quote) "The predicted mortality risk, even in very large countries such as India or China, is less than 100 deaths per year". Being blunt, if this is the mortality risk analysis then the model is frankly wrong as the measured losses are much higher than this. Taking 2008 as an example, a year in which precipitation-induced landslide occurrence was not exceptional, I recorded 778 rainfall-induced landslide fatalities in China, 700 in Haiti and 252 in India. This is typical and is supported by official figures. Of course, every few years these countries suffer a very large landslide disaster (e.g. the Leyte landslide in the Philippines), which increases the average annual numbers. Therefore, the study has fundamentally under-estimated the risks of rainfall-induced landslide mortality still further.

So let's take a look at the maps. They have produced landslide risk maps on a 10 x 10 km grid. Three maps have been generated, which I reproduce below. The maps are for Asia, Central America (plus the NW of S. America) and Central Africa, presumably because these are the three areas with the highest level of landslide risk. Click on the maps for a better view in a new window. Note that the label on the legend of "tropical cyclone risk" is presumably just an error, albeit a rather serious one.

This is my map of fatal landslides for 2006, 7 and 8. Each black dot represents a single fatal landslide:

This map is close to being a direct realisation of the mortality risk analysis, although care must be taken given the short time period that my map covers and to remember that population density may be an important factor. The first thing to note is that the C. American and Asian areas are well-chosen given the high incidence of fatal landslides that I record. I am far less sure of the African area - I really don't record much for that part of the world, although I recognise that this might be because I just don't capture events in this part of the world, perhaps. In Asia the distribution seems to be vaguely right in that it picks up the swathe of events through the Himalayan arc and the high risk in Java, etc. However, it does appear to fail to pick up the landslide risk associated with Central China at all well. This may reflect the high population density here (i.e. although there are lots of fatal landslides, the risk to individuals is low), but I doubt that this is the whole story. My feeling is that the analysis is failing to represent landslides in this area well. A similar problem occurs in SW India, which is a notable hotspot. In Central / S. America the analysis seems to do rather better.

Overall I am left feeling that the representation of landslide risk is really unsatisfactory. It must be possible to do this better. I hope that the analysis of the other hazards is rather better - I am sure that it must be.

Comments welcome.

Landslide hazard and the Guatemala rockslide

As commenters on my earlier threads have pointed out (thanks to them), the location of the landslide in Guatemala can now be pinpointed using a map produced by CONRED. This map comes from a very useful report, with some good images of the rescue and recovery operation, available here. I have reproduced the map below (click on the map for a better view):

Helpfully, this allows the location to be pinpointed on Google Earth (unfortunately the high resolution imagery starts just east of the landslide location - click on the image for a decent view):


Satellite imagery can be difficult to interpret until a 3D perspective is available. This is one of the key strengths of Google Earth. The situation becomes so much clearer when a perspective view is taken:

A magnified and annotated image below shows that the landslide occurred in a very clear bowl shaped feature that would cause any good geomorphologist to be very nervous in terms of slope stability. I have highlighted the boundary of the bowl and the location of the landslide:


Note that there are a number of other locations that look vulnerable to slope instability as well, such as the bowl to the east of the area that failed. Reports suggest that the authorities are being cautious and have arranged evacuations. This is probably prudent, but it is important that a proper hazard assessment is undertaken, and that the risks associated with landslides are then balanced against the (social) risks to the people associated with moving them from their homes and their land.

Young River Landslide, New Zealand

Interesting news from New Zealand, where for the last few months there has been some concern about a landslide dam on South Island. The landslide itself occurred in a fairly remote area of the Southern Alps at 4:40 am on 29th August 2007. The landslide, which is well-described in a GNS Science poster here (there are some great images and some good data on that poster), blocked the river valley to a depth of about 100 metres. This was a big debris slide, with a volume of about 11 million cubic metres and a runout distance of about 1.8 km. Interestingly it does not appear to have created an air blast as large slides of this type often do. This may mean that the mass moved as a series of events closely spaced in time, rather than one big, instantaneous failure.

Over time a lake built up behind it, finally overtopping on 5th October 2007. Understandably, there was concern about the possibility of an outburst flood. In this case there are few human assets at risk downstream, but this is a popular hiking area, potentially putting people on the trails at risk. As a result, the trails were closed by the Department of Conservation whilst the landslide was monitored in real time by GNS Science and Otago Regional Council. Unfortunately, such a closure was not good for the local community as it reduced the number of tourists.

The images below show the landslide from the downslope side. I have annotated it below to show the key features. Note that the deposit has banked up on the right side (from this view). The natural spillway that has formed is just on the lee of this banked up deposit. This deposit is coarse-grained (bouldery), which may well be the reason why the channel has not eroded downwards to release the water.

The image below is from the landslide dam itself looking across the lake. Note the size of the boulders - these are part of the landslide deposit. This does show that if the landslide dam is stable then the resultant lake can in some circumstances become an asset.

This week it was reported here that a decision has now been taken to reopen the trails downstream of the landslide from 1st November (i.e. just before the start of the summer). Unsurprisingly, the local people are rather pleased: "Makarora Residents Association deputy chairman Devon Miller said the closed valley had affected some of the tourist operators in the township, so the decision to re-open was a welcome one."It's a good positive announcement and the community is happy," he said." (Otago Daily Times).

The decision to reopen the trails but to maintain some restrictions in heavy rain, using a new warning system, appears to be sensible. So often landslide management is about balancing risks - i.e. what is the risk of a collapse of the dam affecting someone on a trail compared to the risk to the local communities associated with the loss of tourism, etc. In this case the stability of the dam suggests that this risk has now dropped to close to the residual level. Note that this does not mean that there is no risk - there are hazards associated with spending time in remote mountains. The risk from the landslide dam is no greater, and may be substantially less, than those other risks.

All-in-all the approach taken by the parties involved in New Zealand has been exemplary, in terms of picking up the event in the first place, in terms of the ways that they have monitored it and in terms of the decision-making process to minimise risk.