Evolution of the Gollum Channel System, offshore Ireland: risk assessment of tsunamigenic processes and relevance for regional sedimentary processes.

Most tsunamis we know of have been triggered by megathrust earthquakes in active continental margins. However, tsunamis generated by mass-wasting events on passive continental margins have also been recognized. In this setting, a tsunami is not necessarily preceded by an earthquake (that sets off a tsunami alert), which leads to a potentially unexpected arrival of a tsunami on a coastline. Since most European coasts are located close to continental margins, areas where tsunamigenic mass-wasting events could occur should be identified. Deposits with inferred tsunamigenic origin in southwest Ireland and northwest Wales suggest that the Gollum Channel System to the southwest of Ireland is an area where a “silent killer” tsunami could be generated. Studies indicate that mass-wasting events have happened in this area in the past, and that these events are likely to happen again. This project postulates that the Gollum Channel System is indeed a source of tsunami risk to Ireland. The volumes and reinforcing mechanisms involved in a potential mass-wasting event in this area need to be quantified since the impact regarding loss of life and infrastructure could be very high. An understanding of the origin and evolution of the channel system is in this context of major importance. We propose to assess the risk this area poses with an integrated approach using traditional seismic profiling, as well as very high-resolution near-seabed observation using AUV and ROV technologies.