jpl.nasa.gov/post/series.html). Estimates of wave runup are derived from field observations by the authors and published data. Field surveys of coastal berms or beach ridges in Mahé and Praslin
(Seychelles), Viti Levu (Fiji), Tarawa (Kiribati), and Aitutaki (Cook Islands) by Jackson et al. (2005), Forbes et al. (1995), Forbes and Biribo (1996) and Forbes (1995) respectively, were undertaken using graduated rods and horizon (adaptation of Emery 1961) or electronic total station methods and referenced in most cases to the reef flat, representing a low-water datum, and to local survey control. Surveys in the Seychelles were tied to global positioning system (GPS) control and the mean sea level (MSL) datum using post-processed static differential surveys and tidal records (Jackson et al. 2005). Small island types and associated physical AZD2281 datasheet vulnerability Tropical and sub-tropical small islands can be classified Adriamycin into several broad AZD3965 cost categories on the basis of geology, bathymetry, topography, and geomorphic evolution (e.g., Scott and
Rotondo 1983; Solomon and Forbes 1999; Nunn 1994; Woodroffe 2002). Here we consider tropical oceanic islands under four broad categories (Fig. 2). Fig. 2 Major types of oceanic islands. Horizontal line is present-day sea level high volcanic islands (active or inactive), with fringing, emergent, or barrier reefs near-atolls and atolls emergent limestone islands including raised atolls continental fragments High volcanic islands Volcanic islands have rugged or mountainous interiors and a wide range of summit elevations, among the Guanylate cyclase 2C highest being Mauna Kea (Hawai’i) at 4,205 m. Many older and inactive volcanic islands are lower, reflecting long-term plate motion and subsidence (Scott and Rotondo 1983)
and initially rapid denudation (e.g., Louvat and Allègre 1997). Most oceanic volcanic islands rise from abyssal depths (e.g., Oehler et al. 2008). Rarotonga, with a peak elevation of 658 m above sea level (ASL), rises from an abyssal depth of about 4,000 m, where its diameter is 50 km—five times that of the subaerial island (Fig. 3). Here, as on many high islands, there is a narrow coastal plain or terrace composed of sand and gravel derived from both the reef and slopes above, or in some cases consisting of elevated reef flat limestone or cemented conglomerate. Steep slopes and tropical forest cover limit the use of interior lands for settlement on many islands. As a result, community development, roads, and other infrastructure are concentrated largely along the coastal margin, increasing exposure to coastal hazards (Fig. 3). Fig. 3 Volcanic island of Rarotonga, Cook Islands, 24 June 2007. Image source: NASA (courtesy Wikimedia Commons, http://en.wikipedia.org/wiki/File:Rarotonga_Island.jpg). Black line Island shoreline.