A detailed seismic structure of Rockall Bank (55°N, 15°W) — A synthetic seismogram analysis

Abstract

Seismic data from a 250 km long refraction profile on Rockall Bank have been re-interpreted to determine a detailed velocity-depth structure. The analysis was carried out using synthetic seismograms to match the amplitude and waveforms of the experimental records. The structure obtained from a travel-time analysis alone was found to be inadequate, and the final preferred velocity-depth model is defined more in terms of velocity gradients than of constant velocity layers. In the preferred structure a thin high-velocity layer, 6.7–6.9 km/s, was found in the upper crust at a depth of 7 km and the Moho transition was modelled by a velocity gradient zone 1.5 km thick with the velocity rising from 7.5 to 8.2 km/s. This new analysis supports the conclusion of the previous analysis: Rockall Bank is a continental fragment.