July 2008 fatal landslide map

The map below shows the provisional distribution of fatal landslides for June 2008. The (again provisional) statistics are:
Number of fatal landslides: 55
Number of fatalities: 2127

Once again, the number of recorded fatalities this month has been substantially below the average for 2002-2007, which is 504 deaths. This is consistent with the monthly totals for the whole of the year - indeed at the moment 2008 has the lowest number of fatalities that I have recorded for any year, excluding the Wenchuan (Sichuan) earthquake of course. I will in due course write a post about the likely causes of this very interesting pattern.

Figure 1 shows the distribution map for July. As ever, click on the map for a bigger version. Please acknowledge any use of it or Fig. 2.

Fig. 1: July 2008 fatal landslide locations (click on the map for a larger version)

The effect of the monsoon in South Asia is now being clearly felt, with a very marked line of landslides along the southern edge of the Himalayas. The usual cluster of landslides in Central China is also clear. Once again there is a higher incidence of landslides in Central and S. America than is normal.

Fig. 2 shows all of the recorded fatal landslides in 2008 to the end of July, excluding those associated with the Wenchuan (Sichuan) earthquake. The typical annual patterns are now becoming clear, with clusters in Central China, S. Asia along the southern edge of the Himalayas, the Philippines and Central / S. America. There are certainly more recorded fatal landslides in the latter area so far this year than has been the pattern over the last few years, but there are also rather fewer in the Himalayas. The western part of the Himalayan chain (e.g. Kashmir) in particular seems to have far fewer fatalities than has been the case for the last few years.

Fig. 2: Recorded fatal landslides in 2008 up to the end of July. Each dot represents a single landslide. Click on the map for a larger version in a new window.

Please leave a comment about this map and dataset! I would really like to know what you think about the data, the maps and the general approach.
Of course, if you know of an event that I might have missed I would like to hear from you...

TRMM and landslide monitoring

One of the most admirable science projects at NASA at the current time is an attempt to create a global landslide and flood warning system using the Tropical Rainfall Monitoring Mission satellite data. TRMM using a precipitation radar system to provide near real time data on the intensity of rainfall in the tropical and subtropical regions. NASA then make these data available on the TRMM website.

The usefulness of these data can be illustrated using the last seven days of rainfall in Asia. During this time the monsoon has strengthened - we are just moving into the real wet season in south and SE. Asia. Furthermore, the first really destructive tropical cyclone of the year has just tracked across the Philippines and then made a more-or-less direct hit on Hong Kong, before dissipating in southern China. As well as causing the sinking of a passenger ferry, this typhoon also deposited large volumes of rain that have been responsible for extensive landslides and floods. Using TRMM it is possible to obtain an estimate of the volume of rainfall that has fallen in Asia over the last week (Fig. 1). This does come with a caveat, which is that the spatial distribution of rainfall is very variable at the local scale, which this instrument does not resolve. Nonetheless it does provide a really interesting indication of the rainfall distribution.

Figure 1: TRMM image of the rainfall distribution for the seven days to 27th June 2008 at 06:00 UTC. Note the high rainfall totals for the Philippines and S. China, generated by the passage of Typhoon Fengshan (click on the image for a better view).

The locations of high rainfall appear to correlate with areas of flooding - for example, in this time floods were reported in the Central Philippines, South China around the Pearl River delta and in parts of N. India. Unfortunately, the correlation with fatal landslides at least is far poorer. Figure 2 shows the locations of fatal landslides that I have recorded in the same time period. A caveat is that perhaps not all the landslides in China have yet been reported, so the map in Figure 2 might change a little. However, it is clear that a simple rainfall total algorithm is not enough to provide a really good indication of the distribution of fatal landslides at least.

Figure 2: Locations of reported fatal landslides in the 7 day period shown in Figure 1.

The team at NASA are working hard on their landslide algorithm and are doing a terrific job. This is one of the most interesting landslide projects underway at the moment. I am hoping that they will present some interesting progress in this work at the International Symposium on Landslides and Engineered Slopes in China next week.