Development of site profiles to estimate amplification functions for the North Sea

Abstract

As part of the SHARP-storage project, a new ground motion model (GMM) for the North Sea is being developed. The GMM will be defined for a reference rock condition, and amplification factors to estimate shaking at the soil surface will be derived based on a database of one-dimensional (1D) site response analyses. This paper describes the selection and development of site profiles that will be used in the site response analyses. The tectonic and geological development of the North Sea is complex. The sediments encountered in the North Sea have been deposited in dynamically changing environments ranging from arctic to temperate and reworked by the movement of ice sheets during at least three different glacial periods. As a result, a wide range of soil types and properties are found. To capture this variability, we first developed nine base case profiles representative of different locations and soil conditions encountered in the North Sea. We then modified the nine base case profiles to explore the effects of elastic site period and profile depth. The profiles are based on geological, geophysical, and geotechnical data collected from projects conducted in the North Sea. The GMM and accompanying amplification functions will increase the accuracy of seismic hazard evaluations for critical infrastructure in the North Sea, such as offshore wind farms and future carbon storage sites.