Hawaii as a Site for the Moho Hole-— Woollard 
279 
FIG. 1 . Bathymetric map of the Hawaiian Archipelago, showing proposed Moho Hole site (cross). Con- 
tour intervals in 100 fm. 
that suggests abnormal conditions at depth. 
Similarly, when the gravity (Fig. 3 in Strange 
et al., p. 386 in this issue) and the magnetic 
(Fig. 2) data are examined, no subsurface 
abnormalities such as a buried volcanic pipe or 
crustal faulting are suggested. The shallow 
depth of the Moho, on the basis of the seismic 
measurements, results from up-warping of the 
crust in response to crustal subsidence beneath 
the Hawaiian Ridge. 
Depth of water 
The depth of water at the recommended site 
as indicated is approximately 2380 fm (4350 m). 
Ship positioning, therefore, probably will have 
to be maintained acoustically through signals 
from on-bottom u pingers.” 
Depth of drilling required 
The total depth of drilling required below 
the sea bottom to reach the mantle, according 
to the analysis made by nsf of the seismic 
data, is about 4.6 km, of which about 0.3 km 
is sediment. 
Weather conditions 
The area is remarkably free of storms, bad 
weather, and temperature extremes. The tem- 
perature ranges, in general, between 70° and 
85°. The prevailing trade winds blow at 12-20 
mph from the east much of the year and seldom 
exceed 30 mph. Because of the constancy in 
wind direction, a surface current set to the 
northwest of about 1.0 knot can be expected. 
Storms, when they do occur, are usually from 
the south. In these cases, seas will not be high 
because of the sheltering effect of Maui and 
resulting short fetch. Average swell runs about 
6 ft, and storm waves about 25 ft. Although 
tsunami waves are to be expected, in the open 
sea these waves are hardly perceptible and 
probably no greater than the diurnal tidal 
change of 1-2 ft. 
Seismicity 
There is no record of earthquakes in the 
