Site classification for seismic hazard assessment

Started: October 2014
Supervisor: Fenton, C.H.
Funding: Dixon Scholarship

Background

Over a hundred seismic stations exist across the UK, forming a network that detects national and global seismicity. The record on average a hundred British earthquakes annually as well as monitoring mining activity, arms testing and global earthquakes (British Geological Survey, 2013).

For significant number of these stations, however, the condition of the ground beneath the seismometers remains comparatively unknown. Few installation records were gathered or still exist and no further studies have been conducted creating uncertainty in the effectiveness of stations. This lack of knowledge about the ground conditions prevents correct calibration of the instruments’ records. As a result, the data from these stations were not then being used accurately in design or interpretation with their respective uncertainty. Not knowing these parameters could cause over-design of sensitive facilities at large economic cost or, more critically, cause the under-design of infrastructure that has catastrophic consequences if failure does, in fact, occur.

Research Aims

The aim of the research is to improve site classification for seismic hazard assessment in UK by designing a method to obtain a rigorous understanding of the geological profiles of relatively unknown sites such as the strong ground motion stations. A universal database for in-situ measurements of the shear wave velocities in the UK will be created in order to improve the reliability of this geological understanding. These data will then be used to assess the strong ground motion stations likely V_s30 velocities and their influence on the Ground Motion Predictions Equations.

References

• Baptie, B. (ed.) (2012) UK Earthquake Monitoring 2011/2012: BGS Seismic Monitoring and Information Service. Twenty-third Annual Report. Edinburgh, British Geological Survey.
• British Geological Survey (2013) Seismic Monitoring. [Online] Available from www.bgs.ac.uk [Accessed 20/05/2013]

SARAH TALLET-WILLIAMS
PhD Candidate - Geotechnics 
Department of Civil & Environmental Engineering 
Imperial College London SW7 2AZ 
sarah.tallett-williams09@imperial.ac.uk