Location of Ordnance-Like Objects in Coastal Waters to Depths of 50 Meters

摘要

Many coastal marine sites in the tropical Pacific and elsewhere were the sites ofintensive fire fights during World War II, and others were subsequently used over extended periods by the U.S. armed services and allies as training areas for simulated warfare using live ordnance. The reduction of defense needs has resulted in the termination of many of these activities and some of the islands and their surrounding environs are scheduled to be cleaned up and returned to public use. Identified ordnance discarded in offshore areas includes naval shells, bombs, rockets, torpedoes, mortar rounds, and small arms ammunition, much of it unexploded and some of it buried upon impact or subsequently by sedimentary processes. It is generally understood that areas designated for immediate clean-up extend only to the 50-meter isobath. The Marine Minerals Technology Center (MMTC) has for the last six years been developing techniques for quantitative mapping of seabed mineral deposits. An important class of seabed minerals is the placer deposit, consisting of concentrations of relatively dense minerals, such as gold, tin, and others, which are sorted naturally by wave and current action into shallow seabed accumulations. This pursuit has led MMTC to develop a number of tools and techniques which can be used with relatively small investment to improve the odds of finding and mapping these deposits. In key respects, placers are similar to ordnance in that they are smaller than most geological structures and consist of anomalous concentrations of specific materials in sites which are not easy to predict. The methods developed by MMTC and their collaborators for placers can provide cost effective means for finding and classifying ordnance.