6 
1 Introduction 
In December 2004, when the disastrous tsunami occurred in the Indian Ocean, the coastal 
population and the authorities were totally unprepared. Immediately after the disaster, the 
German Federal Ministry of Education and Research (BMBF) commissioned the Flelmholtz 
Association of National Research Centres to develop a tsunami early warning system for the 
Indian Ocean. A commission to develop a warning system for the Mediterranean Sea and the 
Atlantic Ocean was established later. Scientists at the Federal Maritime and Flydrographic 
Agency of Germany (BSFI, Bundesamt für Seeschifffahrt und Flydrographie), the agency 
issuing the official water level predictions for the North and Baltic Seas, raised the question 
whether a tsunami from the Atlantic Ocean might also pose a hazard to the German coasts. 
At first glance, the occurrence of a tsunami in the North Sea may appear quite unlikely. But 
there is evidence that the European waters have witnessed tsunami in the past. For 
example, a tsunami was triggered by the Lisbon earthquake in 1755. The best studied event 
in northern Europe is the tsunami caused by the Storegga submarine slide about 8000 bp 
(before present, i.e. before 1950). 
The propagation of long waves with amplitudes of up to one metre, tidal waves, and external 
surges into the North Sea is well understood and is taken into account in the daily water level 
predictions. Tsunami are long waves, with shorter wavelengths and significantly greater 
wave heights than the semidiurnal tide prevailing in the North Sea. Prior to this investigation, 
the lead time between the entry of a tsunami into the North Sea from the north and its arrival 
on the German coasts had been estimated at 10 hours. It had also been assumed that a 
tsunami would lose much of its energy on the wide, shallow North Sea shelf. 
In order to provide well-founded answers to questions raised by the public and to obtain 
quantitative data, the BSFI carried out its project “Tsunami - a study regarding the North Sea 
coast“ between 24 January 2005 and 31 August 2005. The scope of the study was limited to 
information that is relevant to the German coasts. It included mainly: 
literature and internet research 
compilation of possible tsunami sources 
compilation of historical tsunami events 
theoretical descriptions of the behaviour of waves propagating from deep to shallow 
waters, wave propagation and damping on wide shelves 
estimated travel times and wave heights 
development of a tsunami modelling concept based on BSFI models 
model simulations using a model system adjusted to the problem. 
After the tsunami issue had also been discussed at other institutions, the BSFI hosted the 
workshop “Tsunami - Eine Gefahr für unsere Küsten?“ (Tsunami - a hazard to our coasts?), 
which was limited to German institutions. Its aim was to enter into a discussion about recent 
findings and possibly define research topics regarding the German coasts. (CD of the 
workshop of 21 June 2005 is available from the BSFI).