Tsunami generation in a large scale experimental facility

•Very long waves (T = O(100 s)) were successfully generated with a piston type wave maker.•Long flume turns out to be necessary for tsunami studies with very long waves.•Requirements for tsunami generation are presented.

Experimental studies on tsunami are carried out since many years, most of them by generating solitary waves with a piston type wave maker. However, today it is more and more appreciated that these kinds of waves actually do not represent a real tsunami very well, as particularly for the shallow waters at the coast the wave length becomes comparably far too short. Recently new generation methods for scaled down real tsunami experiments were suggested, as it was doubted that sufficiently long waves could be generated with a classical wave maker. The present paper shall disprove these arguments by providing results of a study carried out in the Large Wave Flume (Großer Wellenkanal, GWK), where waves of periods between 30 s and more than 100 s at 1 m water depth were successfully generated with a piston type wave maker. Results for elongated solitary waves, trough led N-waves and real tsunami records as a combination of a different number of general solitons (sech2 waves) are presented. Finally, the requirements and limitations to bring a “real” tsunami into the laboratory are discussed.