Marshall Island, High Resolution Bathymetry Survey, Technical report (ER117)

High-resolution bathymetric survey was carried out in Majuro Atoll in the Marshall Islands over a period of 10 days from 18 to 27 July, resulting in the acquisition of 752 km of multibeam echo sounder data. This report describes the marine survey work carried out by the Pacific Islands Applied Geoscience Commission (SOPAC) for Majuro. The resultant data compilation was used to produce bathymetry charts available from the SOPAC geonetwork site as a separate metadata entry. The report is available for download from its appropriate link under Distribution Info. This work was initiated by the SOPAC/EU Reducing Vulnerability of Pacific ACP States Project, under the European Development Fund.The objective of the survey contained in the report was to investigate the seabed and provide information about water depths in and around the atoll using a Multibeam echosounder (MBES).Majuro is located 171 degr12' E and 7degr 09'N.The atolls of Marshall Islands consist of circular to elliptical chains of small carbonate islands associated with a coral-reef platform encircling a shallow, central, seawater lagoon. The atoll islands, which typically consist of reef debris and atoll sediments, are exposed or emerged portions of a thick carbonate platform that has formed on top of a subsided and submerged volcanic edifice. The Marshall Islands sit atop the Pacific Plate and are thought to represent a senescentvolcanic chain produced by a long-inactive hotspot (Scott and Rotondo 1983). Unlike the nearby linear volcanic island chains in the Pacific, the volcanoes that underlie the present-day Marshall Islands are widely scattered and do not exhibit any apparent age linearity.The survey achieved good coverage of the seafloor in the lagoon within the survey area from approximately 10 to 70 m water depths. The eastern nearshore area of the reef slope wasmapped from approximately 10 m depth to an average offshore distance of 5 km, reaching water depths of some 2200 m. The seafloor terrain was found to be highly irregular with anaverage slope of 31 degrees.