Kona Earthquake — Macdonald AND WenTWORTH 
279 
way or more through the wall, and, especially 
in the older walls, occasional slabs are laid 
partly or entirely through the wall to help 
tie it together. Because of the rough, irregular 
surfaces of the fragments it is possible to 
build them into a nearly vertical wall 3 or 4 
feet high and only about 30 inches thick at 
the base. Such walls stand well under ordi- 
nary conditions, but, because of the shortness 
of the bonding surfaces of adjacent blocks, 
they are rather unstable under any joggling, 
such as by earthquakes. The earthquake of 
August 21 caused extensive shaking down 
of the walls. The commonest type of damage 
was a slumping of the upper part of the 
downslope face of the wall, the fragments 
rolling down and out a short distance from 
the base of the wall. Such damage was espe- 
cially common on the north-south trending 
walls and at high places on the walls. In a 
few instances, walls on nearly level ground 
were dislodged almost equally in both direc- 
tions, but the failure was preponderantly on 
the west side of the walls, and the material 
from the walls was displaced westward. 
Some of the westward displacement of 
material probably resulted from the tendency 
of the loose material composing the wall to 
lag behind during the initial strong eastward 
movement of the ground. However, a large 
proportion, perhaps most, of the failures of 
the walls on their west side undoubtedly re- 
sulted from the fact that, because of the 
general westward slope of the ground, the 
west side of the wall was higher and usually 
steeper than the east side, and there was a 
tendency for materials to shift downslope 
under the influence of gravity. 
Well-built walls were surprisingly resistant 
to earthquake damage. Thus, the wall along 
the landward side of the highway from Ho- 
naunau to Napoopoo, built of carefully placed 
rectangular blocks of lava, was almost wholly 
undamaged despite its location very close to 
the epicenter. Likewise, in other parts of the 
epicentral area, older walls in which slabs 
extending through a large portion of the wall 
had been used to tie the wall together showed 
comparatively little damage. 
At the ancient City of Refuge at Honaunau, 
about 20 feet of the seaward side of the main 
outer wall of the enclosure collapsed. It is 
interesting to note that damage was restricted 
to a reconstructed portion of the wall, where- 
as the remaining portions of the original 
enclosure wall and the walls of the heiau 
platforms were undamaged. Homer Hayes, 
a close student of the City of Refuge, has 
made the highly plausible suggestion that 
the peculiar construction of the ancient walls, 
in which occasional broad slabs extend en- 
tirely or largely through the wall and some- 
times bridge open spaces beneath, is respon- 
sible for the greater resistance to earthquakes 
of the old portions of the wall. 
Damage to Roads 
Damage to paved roads was of three gen- 
eral sorts: (1) cracking of pavement, (2) 
cracking and slumping of shoulders and sep- 
aration of shoulders from pavement, and (3) 
collapse of road cuts, causing partial obstruc- 
tion of the road. The latter has already been 
discussed under the heading '’Rock Slides.” 
Minor cracking of shoulders occurred over 
an area extending about 10 miles north and 
12 miles south of the approximate epicenter, 
and a few cracks were formed as far away as 
the northeast side of Kilauea Caldera, 47 
miles from the epicenter. However, extensive 
pavement cracking and slumping were re- 
stricted to the area between Captain Cook 
and Hookena. The distribution of cracks in 
the road is shown in Figure 3. 
Observed cracking or slumping of the 
pavement or shoulders was entirely restricted 
to portions of the road on fills. In building 
the road, some gullies were crossed by laying 
in a rock fill having a batter, or departure 
from vertical, of less than 1 in 4, filling with 
fine material, and laying asphalt pavement 
across the top. Such fills were insufficiently 
stable to withstand the shaking of a strong 
earthquake, and in several places the down- 
