Kilometers 
Structure of Koolau Volcano — Furumoto, Thompson, and Woollard 
313 
w 
10 
20 - 
3.0 km/sec 
4.97 km/sec 
dip l.|° 
6.75 km/sec 
8.8 km/sec 
■Sea Level 
T T "T~ n~ 
10 20 30 40 50 
Kilometers 
Fig. 9. Section structure on south flank. 
dera area, attains a shallow depth of about 
4.3 km. 
The behavior of the 5. 7-6.1 km/sec layer is 
curious, because it appears clearly in the K-K 
series but was undetected in the GASHOUSE 
series. Hence, we have the interpretation that 
this layer pinches out at the north end of the 
plug. 
The section structures from BRAVO series 
and GASHOUSE series have been juxtaposed for 
the southern flank. Because of the disparate 
character of the two, the grounds for juxtaposi- 
tioning may not be as firm as those for the rift 
zone and the plug; but the composite picture 
fits well with the gravity survey (Strange, Wool- 
lard, and Rose, p. 381 in this issue). The 
depth of 21 km for the Mohorovicic discontinu- 
ity for the southern flank is deeper than normal 
for oceanic areas, but far from startling for vol- 
canic islands. The results of refraction surveys 
by the U.S. Geological Survey show that along 
KM 
Fig. 10. Section structure of Koolau Volcano from composite seismic refraction data. 
