5 July 2019
The Aizawl landslide: evidence from Google Earth of slope modification
The landslide in Aizawl in Mizoram, India earlier this week, which I featured on Wednesday, caused the death of three people, including two children. The image below, from The Sentinel, provides an interesting perspective on the landslide. Once again it emphasises how fortunate it is that the buildings did not collapse completely:-
There is an excellent archive of Google Earth imagery for this site. As a reminder, here is an image from December 2018 showing the completed site and the slope that ultimately failed:-
By comparison, this image, dated 17th February 2006, shows the site prior to construction. Note the path across the slope that was widened to build the road:-
But the revealing image of the side is the one below, dated 3rd December 2012, which shows the ground works at the site prior to the construction of the blocks:-
At the point at which this image was collected machinery was onsite excavating the foundation for the blocks in the row that was hit by the landslide this week. The footprint of other blocks is in place, and there is evidence of fill being emplaced lower down the slope. Note that the road has been constructed through cutting the slope and then emplacing fill on the downslope side.
A subsequent image, this time taken in 2014, appears to show that the slope was cut across the entirety of the length upslope of the apartments:-
It is not clear as to the level of engineering works that were used to secure this cut slope, but the subsequent failure suggests that for whatever reason they were not adequate.