Y~-. Headquarter~-dnt Task Force STVEN Arl@ton HL station ArlingtonU, Virginia 8 Febzuary1958 Annex M to JTF SEVEN OperationPlan No. 1-58 NATURALDIsASTERPLAN 1. Gi%NEIML a. The purposeof this plan is to establishresponsibilities and to set forth titructiona to all unitsof the task forceto cope with conditionswhich may arise as a reeultof a typhoon or tidal wave. The intentionis to pmd.de for the preservationof life and property during the actual courseof the disturbanceand the early restoration of essentialservicesafter it has passed. b. In order to provideTG Commanderswith adequateguidsncefor issuance of their own individualdetaileddisasterplans,more specificinstmctions pertainingto emergencyevacwtion will be publishedas AIKISXN to this operationPlan. c. L?efinitions (1) Twhoon. /4tgphoon is a violentcyclonicstonriof tropicalorigin with wind speeds of sixty-five(65) knots or more. The area of deetmctive winds within a typhoon is extremelyvariable, occasionallyas small as a circleof fifty (50) miles in diameter and, in other cases as large as a circleof 9fJ3miles in diameter. (2) Tidal Yave. A tidal wave bears no relationto the oceanictides but ia the result of extremelylarge displacementsof water in the ocean cauaedby earth slippage. Uost tidal wavm in the Pacificoriginatein the Gulf of flasks,where earth slippages are not rare. The av8ragetidal.wave has the followingcharacteristicsin deep water: Wave length- 100 miles “Javeheight- 2 to 3 feet in the Marshall Islands Wave period - 1S to 60 minutes Wave velocity- 500 knots in deep water. The destructiveenergy releasedby a tidai wave occurswhen it entera shallowwater, increasesin height and breakson or near the slmre line. Destmction associatedwith such a wave is causad by the rapid rise in water which undexmbes foundations, cd.lapsesstructuresand drownsperaomel. The difficult y in copingwith a tidal wave stcma from the fact that it cannotbe seen in deep water (the slope is about one (1) foot in 6,OOO feet or more) and that it moves at such a high rate of speed. The primarymeans by which the existenceof a tidal wave is detetined is throughthe observationof etih slippagesby use of seismographs. A seisnvgraphwarning net exietein the Pacific and CJTF SEVEN will receivewarnings from CINCPi\C ●r other Pacific Commandsvia the faatestpossiblemeans. CINCPAC Inatxuction 34.6, SeismicSea ‘:’ave (TidalViave ) Warning,disseminatesinstructionsin regard to the tidal wave warning system in use in the PacifLcarea. d. The newer llPacific” stricturesh the EFC have been designedto tithry buildingfl stand winds of 105 miles per hour. The so-calledI!multisto on JANET Island is well constructedand capableof withstanding typhoon forcee. All wooden structureson the atolls are considered , M-1