The main image shows the average annual subsidence velocities in London, coloured so that red shows areas exhibiting high rates of subsidence, blue areas exhibiting high rates of ground swelling. Note that the coloured regions result from interpolating the displacement rates, from the individual data points outwards to the intervening areas, in order to produce a continuous velocity field. This interpolated colour map is used solely for visualisation purposes, whereas the recorded displacement measurements correspond to the individual PS point locations (not shown on this interpolation). Two linear features of subsidence, which may be due to tunnelling, can be readily identified. The first extends from Wandsworth Town, through Battersea, to the Battersea Power Station. The second stretches from Bermondsey to the Houses of Parliament via London Bridge, Southwark and Waterloo station.

The chart shows the displacement history of the highlighted PS point in the Westminster area. It is evident that the subsidence started occuring at the beginning of 1996 and may have been continuing in January 2000 when the last measurement was made. A displacement history chart such as this is produced for each and every PS point identified.

The London results were processed by NPA with Tele-Rilevamento Europa's (TRE) PSInSAR software.

Top