Local Tsunamis and Submarine Landslides in Selected Pacific Island Nations
Presented by Dr. Susanne POHLER on 23 Sep 2013 from 17:15 to 19:15
Type: Poster presentation
Session: Poster session
Track: Poster presentations
In the 1990s several modest earthquakes generated surprisingly large tsunamis without any significant transoceanic tsunami. A number of studies investigated these local tsunami events and concluded that submarine landslides were to blame. It seems timely that Pacific Island Nations investigate the nature and location of submarine landslides and unstable slopes. The Pacific Island Countries (PICs) which constitute the USP region are of four principal types: (1) Islands located over active subduction zones (Solomon Islands, Tonga and Vanuatu); (2) High volcanic Islands which formed over thermal plumes (Cook Islands, Western Samoa); (3) Atolls which formed over long extinct and subsided seamounts (Kiribati, Marshall Islands, Nauru, Niue, Tokelau, Tuvalu); (4) Islands located over an extinct subduction zone (Fiji). Each one of these settings is prone to different types of slope instability but all have in common that submarine landslides are frequent and often predictably occurring at certain sites e.g., fault zones, river mouths, gas hydrate fields. Submarine landslides are often retrogressive hence identifying their location is important. For the purpose of this paper the location of submarine landslides will be compiled from available bathymetric data and published reports. Known landslide generated tsunamis in the PICs of the USP region will be reviewed and a compilation of various causes and triggering mechanisms deemed responsible for slope instability and failure in the four different island settings will be evaluated.