From Technical to Tents- Offshore Geohazards and Tsunami Risk Assessment
Brian G. McAdoo
Blaustein Visiting Professor, SES
Department of Earth Sciences and Geography
Vassar College
Offshore geohazards is usually a pseudonym for submarine landslides. These mass movements that occur on continental slopes worldwide are indeed a hazard, but in themselves do not constitute a threat to human populations. Oil infrastructure is at risk- pipelines break, rigs become unmoored- as well as transoceanic cable systems. However the most significant hazard that can result from a submarine landslide is a tsunami. Understanding the occurrence of offshore landslides (in time and space) not only informs us of potential hazards that lurk offshore, but can yield critical insight into the process most often associated with their formation- earthquakes. Earthquakes undoubtedly produce the world?s most deadly tsunami, and our efforts help define the areas that need attention.
In this talk, I outline what we know and don't about submarine landslides and tsunami, and I finish with how tsunamis affect communities on land. There are dramatic examples of tsunami triggered by these landslides, including the 1929 Grand Banks event (Canada?s worst earthquake-related disaster) and the controversial 1998 Papua New Guinea tsunami. Landslides also inform us about earthquake tsunami by highlighting areas of interest. Rapid-response post-tsunami surveys in areas including Sri Lanka, Indonesia and the Solomon Islands demonstrate the need for an interdisciplinary approach to risk assessment and hazard mitigation. Inputs from scientists (geologists, ecologists, social) and engineers are critical in the early stages of a region?s post-tsunami recovery, and there is a clear need for an integrated approach to post-disaster reconstruction before policy changes are instituted.