Modelling Potential Rates of Natural Subsidence using Geological and PSI Ground Motion Data: An Experiment in Europe and Great Britain

Abstract

Sixteen of the world’s largest cities, with populations of over 10 Million, are located within 100 km of the coast (as are sixteen European cities, with populations of over 1 Million). The need to understand the contribution that the lowering of the ground surface, through natural geological phenomena, can make to estimates of relative sea level change is especially relevant to these lowland areas, which are usually the most geologically susceptible to subsidence. In this work, the methodology developed within the SubCoast EC-FP7 project was exploited to create a combined natural sub-sidence potential percentage change value for each lithology of the OneGeology dataset for Europe. Calibration of potential volume changes against ground motion statistics extracted from interpreted Persistent Scatterer Interferometry (PSI) and geohazard mapping datasets allowed for the deriva-tion of potential ground motion rates for the coastline of Europe. By utilising this subsidence po-tential methodology and combining it with the British Geological Survey (BGS) geology (superficial and bedrock) 1:50,000 scale dataset, a nation-wide dataset of potential natural subsidence rates was produced for Great Britain, providing information for all lithologies of the country. By incorporating the most current and up-to-date PSI data, the potential subsidence rates could be re-calculated, and a more detailed, calibrated polygon dataset could be created in the future. SubCoast was a collab-orative research project funded by the EU, the aim of which was to assess the combined impact of sea level rise and coastal subsidence as measured with satellite radar interferometry.