Predicting deformation around El Asnam, Algeria via forward modelling based on elastic dislocation theory

David Healy1, Graham Yielding2 and Nick Kusznir1

1 = Department of Earth Sciences, University of Liverpool, Liverpool L69 3GP, UK

2 = Badleys, North Beck House, Hundleby, Spilsby, Lincolnshire PE23 5NB, UK

dhealy@liverpool.ac.uk

Continuum mechanical models based on linear elasticity have been used to predict the mode and distribution of fractures across a range of scales. The predictions and implications inherent within these models can be tested against field observations recorded in the aftermath of large onshore earthquakes. This paper presents forward models based on elastic dislocation (ED) theory of the surface deformation due to the Ms = 7.3 earthquake at El Asnam, Algeria on October 10, 1980.

Using fault parameters from previous seismological studies to define a set of larger faults, our models calculate displacements, strains and stresses in the surrounding rock volume. We then compare the predicted strain and stress fields with the surface deformation measured in the area immediately following the 1980 earthquake.

The ED models presented are non-unique solutions, but agreement between modelled and measured strain and stress patterns adds confidence in the use of ED theory to accurately predict deformation around measured faults. ED forward modelling of faults resolved on reflection seismic profiles can aid prediction of small-scale, sub-seismic fracture patterns in faulted hydrocarbon reservoirs.