Engebi showed the largest amount of interior cracking. This consisted of three nearly vertical cracks at the center and quarter points re~

spectively of each wall. These cracks varied in width from .01 inch to
.03 inch; the center crack on the north wall was .04 inch to .05 inch
wide. No cracks were noted at the corners. Roof cracks consisted of two

east-west cracks less than .02 inch in width extending across the floor
in an east-west direction and connecting the quarter point wall cracks;
all other vertical wall cracks did not extend into the floor, There was
a small area of irregular cracking between the main panel and the eightcylinder engine probably caused during the installation of the engine.
All of these cracks appeared to be recent ones and are not believed to be
contraction cracks which occurred during curing of the concrete,
Runit has no evident wall or roof cracks. Two small irregular cracks
occurred in the floor. It is believed that they were of no consequence.
The Aomon Group has three vertical cracks .02 inch or less in width

and on the face-on and side-on walls, extending from the floor to a

height of eight feet. The top of these cracks terminate at what is believed to be a construction joint. One vertical crack .O1 inch in width
exists above the door to the ceiling. A very small number of very fine
hair cracks exist in the floor. It was difficult to determine if these
cracks were definitely the results of blast. It is probable that they
were,

Station101 - Wood Frame Structure.

Structures at Bogallua and

Bogombogo were not damaged. The structure at Muzin was completely
wrecked and the structure at Kirinian was partially wrecked, The roof
was intact, but the side framing was broken and pulled apart. These
structures were designed for weather protection only and are adequate for
this purpose,
Stations 120a, b, c, d, and e — Reinforced Concrete Blocks Set in
Ground, EncasingSteelBottle. Station 120a at Engebi was blown partially
out of the ground; Station 120d was moved about two inches. Movement in
both cases was away from zero. None of the blocks was structurally damaged by the blast, but the special stucco was torn loose along the edges

of the tops of the blocks, and the exposed mesh reinforcement was burned,
There was no damage to the top plates and interior pipes.

The structures at Eberiru are all within the blast crater and were
under water when inspection was attempted; therefore no data is available
at this time,
stations 12la, b,c, d, and e ~ Reinforced Concrete Block Set in

Ground with Steel Casting.

Structures at Engebi were not seriously dam

aged by the blast. Station 12le was blown slightly up and backwards; the
special stucco finish on Stations 12la, b, c, and d was torn loose around

leading edges, and the mesh reinforcement was burned, There is no evidence of structural failure of the castings or the concrete blocks. The
design is considered structurally adequate.

5-311

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