Impact of faulting on development in London

View of the city of London looking towards the Gherkin and Lloyds of London.

Traditionally the London Basin has been considered to be 'relatively simple' , for example, on the current geological maps for the region only a couple of faults are shown.

However, there is a growing body of evidence from recent site investigations suggesting that the structure of the basin is more complex.

The nature and extent of faulting within the London Basin is difficult to determine because the majority of the basement is at subcrop level, buried beneath thick superficial deposits related to the development of the River Thames.

Fault modelling in the Chalk under London

Chalk fault model for central London.

In order to determine the structure of the Chalk in the London Basin, a combined cognitive and numerical approach to model construction was developed (Royse, 2010).

A major difficultly in understanding the structure of the Chalk in the London Basin is that the Chalk is largely unexposed. The project (funded by the Environment Agency) had to rely on subsurface data such as boreholes and site investigation reports.

Although a high density of data was available problems with the distribution of data and its quality meant that, an approach based on a numerical interpolation between data points could not be used in this case.

Therefore a methodology was developed that enabled the modeller to pick out areas of possible faulting and to achieve a geologically reasonable solution even in areas where the data was sparse or uncertain.

The resultant 3D model for the London Basin was more consistent with current geological observations and understanding. The analysis and interpretation of this model has resulted in an improved understanding of how the London Basin evolved during the Cretaceous period.

References and further reading

Royse, K R, De Freitas, M, Burgess, W, Cosgrove, J, Ghail, R, Gibbard, P, King, C, Lawrence, U, Mortimore, R, Owen, H and Skipper, J.   In press.   Geology of London, UK.  Proceedings of the Geologist Association.

Mortimore, R, Newman, T, Royse, K R, Scholes, H and Lawrence, U.   2011.   Chalk: its stratigraphy, structure and engineering geology in east London and the Thames Gateway.   Quarterly Journal of Engineering Geology and Hydrogeology.

Royse, K R.   2010.  Combining numerical and cognitive 3D modelling approaches in order to determine the structure of the Chalk in the London Basin.   Computers and Geosciences 36, 500–511.

Royse, K R, Kessler, H, Robins, N S, Hughes, A G and Mathers, S.   2010.   The use of 3D geological models in the development of the conceptual groundwater model.   Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 161, 237–249.

Contact

For further information contact Dr Katherine Royse or Enquiries