Ne RR te er te ere Te te ee Mr. William Foster of the Hydrographic Office, assisted by Messrs. Grimm and Griffitas of that office, is in charge of the survey. Tne USS Cocopa (ATF, commanded by Lt. Peterson, USN) is on hand for conducting the survey. The Cocopa will act as mother ship to the 42-ft boat, wnich will work close in to tue ocean side of the reef to make tne soundings. Waile weiting for the arrival of the missing supplies the team nas been engaged in dressing up island targets set by Holmes and Narver survey crews for positioning tne snip. been set. Some additionéI targets have Vertical profiles of tne reef will be taken at 500-yd intervals for a distance of 5 miles eituer way from Elugelab, and at intervals of one mile around the remainder of tne reef. Project 11.2 Scaled Ground Snock Tests Tne field work for tiis project was completed in March end April 1952, Five niga-explosive shots (Composition Cp and Tetrytol) equivalent to TNT tonnages of 1, 5, 10, 15, and 20 tons were fired at water level near tre future snot point on Elugelab. Seismic recordings of tue ground shock were made at San Ildefonso, Engebi, Runit, Rigili, and Eniwetok. A preliminary report on analysis of the seismic records has been received from the U. S. Coast and Geodetic Survey. The recorded ground motions were irregulay, resembling earthquake motions, two successive wave cycles seldom being alike. fn analysis of the records from one station which showed similar wave patterns for four of the five snots was made to determine relative