Bathymetry of Cannikin Lake, Amchitka Island, Alaska, with

cavity-radii from the point of the explosion. At the land surface, the
ground lifted and cracked from the force of the explosion {fig. 2).
Thirty-eight hours after the explosion, temperatures and pressures in
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the underground cavity subaided sufficiently for the overlying rock to
collapee into the cavity. The collapee initiated the growth of a rubble I
chimney that extended to the land surface, forming a collapse stnk (ground
surface depreanion) with associated fractures and faults.
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The daepeot part of the trianmlar colhpre sink warn offset about
1,500 ft (460 m) east of GZ (ground zero), the murface location of the I
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8mpLacamnt hole. Thin topographic closure captured surface-water runoff
from 84 percent of the aurroundinng drainage aru (fig. 2). Stage recorders I
placed in the collapse mink Jn July 1972 nhowed that u lake began to form I
in August and began to rpill into the lower reaches of White Alice Creek
by December 1, 1972. Thim lake, commnly referred to as Cannlkin Luke by
the AEC (U.S. Atomic Energy Commission) md it8 contractors, was the first
lake created by an underground nuclear explomion.
The USGS (U.S. Geological Survey), in cooperation with the UC, has
the responsibility to docmnt and to interpret the geologic and hydrologic
effects of nuclear explosions. An accurate description of collapee @inks
is part of thie reaponoibility.
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The formution of a hke within the collapne sink is a unique geologic
and hydrologic effect of an underground nuclear explosion. Cannikin LLae
ptwideo an opportunity to conduct bioenviro~wntul studies of a newlyformed
aquatic habitat and to determine dilution patterns in the event of I
radioactive lealuge. An accurate description of the lake bottom and I