Prospects for tsunami detection and characterisation with HF skywave radar

The Indian Ocean tsunami of Boxing Day, 2004, stimulated interest in the potential of HF radar to provide early warning of such threats. Almost all of the resulting activity focussed on HF surface wave radar (HFSWR), and in at least one case, deployment of a dedicated HFSWR tsunami warning system has eventuated. Yet, while the efficacy of HFSWR in this role is not in question for situations where a wide, shallow continental shelf exists, there are many vulnerable coastal sites where the sensitivity of conventional HFSWR systems would not permit detection at ranges sufficient to provide a meaningful warning time. This paper considers an alternative HF radar technology - skywave radar - and explores alternative signature domains which might provide a means to detect and measure the characteristics of tsunamis at ranges of thousands of kilometres.