Circue-shaoed submarine scarp 220 m high, extending back 190 m inte the node-n reef, and 1000 m alcng the rsef trend. The scarp exposed alder, steeply dipoing beds belcw 220 m aling which the rockfall detached. They samplec this exposure and the natural fere-reef slope surrounding it in 1°84 ard 1965 using a manned submersible. The natural slope in this area is characterized by three zene: .1) the reef piate, crest, and near Tore reef that extends fron sea level to -16 m, with a slope of less than 10/sup 0/, (2: the bypass slope that extends from -16 to -275 m, with slepes of S5/sup O/ decreasing to 35/sup 0/ near the base, and (3) a debris slope of lees than 35/sup ¢/ below ~-275 m. Vertical walis, grecves, and chutes, common on ether fore-reef slopes, are sparse cn the northwestern siepe of Enewetak. The scarp exposes three stratigraphic units that are differentiated by surficial appearance: (1) a near-vertical wall from the reef crest to 76 m that appears rubbly, has cccasional debris-covered ledges, and is composed mainiy of corals; (2) @ vertical te ceverhanging wall from -75 m to -220 m thet i¢ massive and fractured, and has smacth, blocky surfaces; and (3) inclined bedding beicw -220 m along which the slumo block has fractured, exposing a dip siope of hard, dense, white limestone and delaomite that extends Seiaw -400 m. Caves cccur in ali three units. Cpen cemert-lired fractur2s and voids layered with cements are most commen in the middle mit, which now lise within the thermocline. Along the sides cf the scare epreod fore-reef boulder teds gipring at 2o/sup o/ toward the apes : the steerter (35/sup O/) digping natural surface truncates these ceds, ch Gives evidence cf the erasionsl nature cf the bypass sicpe. te 1032} EQE-S7 2119509 Camma-ray spectrum of the radiacctive super-hydgregen barb test excicsiia cn March 1, 1954 dust preduced oy tre Sutnmor: shimizu, Sakae Affiliation: byctea Univ., Japan Cectererce Titles 3. international symocsium an radiation pnysics Centerenze Lecetion: Ferrara, Iteiy Conference Gate: 39 Sep 1985 Scarce: facil. Instrum. Methods Frys, Fes... Sect. &. (Netherlands) v etai./é,. Date: if far 19787 i?7-18e p. aiden: NIMAE Report Na.: CONF-@S0925- Dacument Types Journal Article; Conference iiterature Language: English Journal Aarncuncement: EPBE707 Subfiles INIS (nen-US Atcmindex input AIX) Work Location: Japan Abstract: The super-hydrcgen bemb test explasion, the se-called Brava test of a fission-fusien-fission bomb, was carried cut on Bikini Atel] in thea mid-Pacific on March 1, 1954. Twenty-three Japanese fishermen en beard @ fishing beat about 906 miles north-east cf the test site were attacked urexpactediy by tne falleut, radicactive fine debris of coral reef. Within several mantns after the accident Ev radiochemical analysis about 20 different meclides cf fission products and, in addition, a considerable ancust ef “/fup 235/U were discovered fram the fallout. As we have been prese-ving a minute amount ef the original fallout dust coliected on beard the fisring boat 3i years age, measurements of ..gamma.. rays from it have I004b34