August fatal landslide data

The end of the month marks the point at which I post the accumulated totals for fatal landslides, based upon the global fatal landslide database that I maintain.  The raw figures for August are stark.  The total number of fatal landslides recorded in the month was 71, resulting in 2,740 fatalities.  This total is of course dominated by the Zhouqu landslide in China, which is reported to have resulted in 1,765 deaths.  (Click on read more to access the remainder of this post).


These totals continue the exceptional trend of landslide occurrence in 2010.  The average number of recorded fatality-inducing landslides in August in the period 2002-2009 is 46.7, resulting in an average of 348.3 deaths.

This graph illustrates the magnitude of the anomaly for 2010 to date.  This shows the cumulative total number of recorded fatality-inducing landslides for 2003 (which had the lowest total of any year on the database), 2009 (the previous record year), 2010 to the end of August, and the average for 2003-2009.  There is no doubt that 2010 is exceptional:

It is interesting that these totals have been recorded in a year that to date has had exceptionally low levels of tropical cyclone activity - indeed Northern Hemisphere tropical cyclone energy release remains at the lowest level for 30 years.   When they occur, landfalling NW Pacific tropical cyclones (typhoons) have a major impact upon landslide occurrence.  It is notable in particular that the Philippines and the Caribbean islands (especially Haiti) have been spared substantial tropical cyclone events to date this year.  Given that there are strong signs that tropical cyclone activity is currently increasing in both the N. Atlantic and the Pacific, the next month will be very interesting.

Of course, the root cause of the exceptional occurrence of recorded landslides in August has been the intensity and volume of rainfall associated with the summer monsoon, primarily in China and Pakistan, and to a lesser extent Nepal.  The monsoon should start to weaken during September, but more landslides are likely in the interim given the near-saturated state of the ground.

Fatal landslides in 2010: a half term report

Long term readers of this blog will know that one of its original purposes was to disseminate the work that I do collating data on fatal landslides worldwide.  As the Attabad situation reduces in its intensity I plan to return to some of those key themes.  So here is a half term report on the occurrence of fatal landslides in 2010.

Numbers of landslides:
As of the end of 30th June I had recorded a total of 235 fatal landslide events worldwide, with a distribution by month that looks like this:

This is the highest number of fatal slides for the first six months of the year that I have recorded to date (i.e. since 2003).  In comparison, this graph shows the cumulative total number of fatal landslides for 2010, for 2009 (the previous record) and on average across 2003-2009:

So clearly the number of landslides is running well ahead of the norm for the end of June (remember that globally the main landslide season is in July to September due to the effects of the Asian monsoon.  It is not clear why this should be the case, but it may be associated with the transition from El Nino to La Nina conditions. 

Loss of life:
The number of recorded fatalities is 2,168, with the monthly distribution looking like this:

Again, this is much higher than for an average year, as the cumulative total plot demonstrates.  Note that the previous highest year was 2006 in this case - 2010 is just below this total, but has shown a consistent trend throughout:

Largest events:
The largest event in terms of recorded numbers of fatalities was the 2nd March 2010 landslide at Nametsi Village, Bududa in Uganda, which killed 358 people.  However, the numbers killed by landslides in the Haiti earthquake remains unknown.


Worst affected countries:
The top ten countries in terms of numbers of fatalities is as follows:

1	China	467
2	Uganda	373
3	Brazil	334
4	Guatemala	184
5	Indonesia	118
6	Peru	103
7	India	90
8	Pakistan	61
9	Bangladesh	55
10	Kenya	23

Given the high level of landsliding so far this year, the next few months will be interesting.

Fatal landslides in July 2009 - map and report

Below is the fatal landslide map for July 2009. Each yellow dot represents a single landslide that killed a person. The background is the etopo1 DEM, with the darker colours representing higher terrain. As usual clicking on the image should provide a high resolution view. The image is a GIF so you should be able to download it, but please acknowledge the source.

You will see that in July the focus has very much switched to Asia, with the effect of the (weak) monsoon along the length of the Himalayas being fairly clear. Note also the clear evidence of fatal landslides in Central China, reflecting the heavy rainfall there, and in Japan. There is very little going on in the Caribbean and in SE Asia at the moment - this is not unexpected for the time of year.

The statistics are as follows:
Number of fatal landslides: 65
Number of fatalities: 366

The average for July for 2003-2008 was 468 fatalities, meaning that 2009 was substantially below average. The cumulative number of fatalities for 2009 is 1328 to the end of July, substantially lower than the long term average cumulative total of 1574 (excluding earthquakes of course). Indeed, only one year (2008) has had a lower cumulative total at this point.

Comments and corrections are welcomed. Thanks to all who have helped to put this together.

Fatal landslides in 2009 so far - a review on the solstice

The summer solstice today seems like a good time to take stock of the position with fatal landslides to date, as collected in the Durham Fatal Landslide Database. Globally the fatal landslide season really starts in early June, the point at which the Asian monsoon starts to generate substantial amounts of rainfall in South and East Asia. Of course the greatest proportion of landslides occur in July and August, so we are before the main event.

So, how does the year look so far. Well, interesting actually. The graph below provides the cumulative number of recorded fatal landslides for 2007, 2008 and 2009, excluding the ones triggered by earthquakes (which obviously don't have a seasonal pattern). Obviously for 2007 and 2008 the full year graph is available.


You should be able to see that for 2007 and 2008 the normal S-shaped curve is clear, with a fairly low rate of increase in the first and last c.120 days. The time before this period, the northern hemisphere summer, shows a much greater rate of fatal landslides (i.e. a steeper line). It is also clear that in 2009 to date the number of fatal landslides is above the previous two years, although it is converging a little of late (of which more below). 2008 was anomalously low - 2007 is far more of an "average" year - although note that this is mostly because of the low number of recorded fatal landslides in the early part of the year.

The second graph, below, shows the recorded number of fatalities (again excluding those caused by earthquake-induced landslides). The coincidence between the patterns in 2007 and 2009 is very striking; again 2007 was very close to an average year on this measure. The comparatively low total at this point in 2008 is notable - but it is also clear that the rainy season resulted in a large number of fatalities (the large step is mostly due to hurricane-induced landslides in Haiti, plus a very active monsoon at this time).

One other aspects of this years data is really interesting. You may have noticed that in both the number of fatal landslides and the number of fatalities the trend in the last few weeks is a little anomalous. In particular, I would expect to see the steepening trend becoming clear as the Asian rainy season starts. However, this is clearly not the case as yet, as the graph below shows more clearly:

Here the blue line is the cumulative total of fatalities and the green line is the trend for fatal landslides. The recent flattening off is clear. This is mostly a clear indication of the rather strange pattern in the development of the South Asian monsoon this year. The northern passage of the monsoon appears to have stalled, as this map from the Indian Meteorological Agency shows:


Here the red lines are the average position of the monsoon front, whilst the green are the conditions observed this year. It appears that the northward advance is two weeks or so late at present - and it appears that this is being reflected in the fatal landslide data. However, the northward advance of the monsoon has apparently restarted this weekend, so the more usual trend may start to be displayed shortly.

Interestingly, there is some evidence that the SW Monsoon is weaker in El Nino years, and conditions are changing from La Nina to El Nino present. We are also recording more fatal landslides in South America than in recent years. However, it is far to early to tell whether the patterns that we are seeing this year are really associated with the possible El Nino conditions. It will be an interesting summer!