Modeling of Strong Ground Motion from Earthquakes in the North Sea Area

Abstract

This paper contains calculations of the horizontal ground motion that may result from earthquakes in the North Sea region. Two different models of the North Sea crustal structure are investigated. The synthetic seismograms contain all wide- angle reflections, refractions, their multiples and surface waves in the frequency band between 0 and 1.25 Hz. Simple approximate formulae, relating signal duration with epicentral distances, and peak or rms displacement or accelleration with magnitude, distance and sedimentary cover are presented. Due to the relatively large depth to the basement, ground motion in the North Sea is weaker than in the Western U.S. by a factor of about 3.