Rise of Sea Level at Honaunau — -Apple and Macdonald 
135 
area is far from the rift zones of either Kilauea 
or Manna Loa, and both it and the Honaunau 
area appear to be examples of a general sinking 
of the island. 
Thus, there is evidence of considerable re- 
cent change in the relation of land and sea along 
the shore of the island of Hawaii, or at least of 
the southern part of the island occupied by the 
active volcanoes. A change of this sort could 
conceivably be the result of either a rise of sea 
level or an actual sinking of the land mass, or 
both. A worldwide rise of sea level has indeed 
been taking place, but during the last century 
it has amounted to only about 4.5 inches (Guten- 
berg, 1941:729), and the average rise over the 
last 2,000 years has been only about 3 inches 
per century (Shepard, 1964). Thus the changes 
of roughly a foot per century at Honaunau and 
of several feet in the last few centuries at Keaau 
are three or more times as great as the rise of 
sea level. Most of the change must be attributed 
to sinking of the island. 
The mechanism to explain the sinking of the 
island is readily available. The great pile of vol- 
canic rocks that forms the Hawaiian ridge is a 
load on the earth’s crust which, if the generally 
accepted principle of isostasy is correct, should 
produce a sinking of the crust and the island 
ridge to restore equilibrium. Seismic evidence 
suggests that the base of the crust is bowed 
down beneath the islands (Eaton and Murata, 
I960), presumably due to this cause, and the 
broad trough on the sea floor adjacent to the 
islands has been attributed to a regional sinking 
of the crust to partly re-establish isostatic equili- 
brium (Yening Meinesz, 1940). The older, 
more northern islands are believed to be partly 
compensated isostatically (Woollard, 1951), but 
the island of Hawaii appears to be largely 
uncompensated (Goranson, 1928; Duerksen, 
1943). Although the continuation of the sea 
floor trough around the island of Hawaii sug- 
gests that some sinking, and consequently some 
compensation, has in fact taken place, the still- 
growing volcanic mountains must constitute a 
crustal mass that is tending to sink. The actual 
sinking indicated by the shoreline evidence al- 
most surely is the result of isostatic adjustment. 
REFERENCES 
Apple, R. A. 1965. Trails: From Steppingstones 
to Kerbstones. Bishop Museum Press, Hono- 
lulu. 73 pp- 
Barrere, D. B. 1957. A reconstruction of the 
history and functions of the Puuhonua and 
the Hale o Keawe at Honaunau. In: The 
natural and cultural history of Honaunau, 
Kona, Hawaii, Unpubl. manuscript, Bishop 
Museum, VoL 2, pp. 38-80. 
COAN, T. 1869. Notes on the recent volcanic 
disturbances of Hawaii. Am. J. Sci. Ser. 2, 
47:89-98. 
Duerksen, j. A. 1943. Gravity-anomalies and 
meridian deflection in Hawaii. Am. Geoph. 
Union Trans. 24 (Part 1) : 34—39- 
Eaton, J. P., and K. J. Murata. I960. How 
volcanoes grow. Science 132:925-938. 
Ellis, W. 1917. A Narrative of a Tour Through 
Hawaii in 1823. . . . [Reprinted from the 
London edition of 1826.} Hawaiian Gazette 
Co., Honolulu. 442 pp. 
Emory, K. P. 1957. Honaunau in transition to 
the present. In: The natural and cultural his- 
tory of Honaunau, Kona, Hawaii. Unpubl. 
manuscript, Bishop Museum, VoL 2, pp. 32- 
37. 
Finch, R. H. 1925. The earthquakes at Kapoho, 
island of Hawaii, April 1924. Seismol. Soc. 
Am. Bull. 15:122-127. 
Goranson, R. W. 1928. The density of the 
island of Hawaii, and density distribution in 
the earth’s crust. Am. J. Sci., Ser. 5, 16:89- 
120 . 
Gutenberg, B. 1941. Changes in sea level, 
postglacial uplift, and mobility of the earth’s 
interior. Geol. Soc. Am. Bull. 52:721-772. 
Ii, John Papa. 1959- Fragments of Hawaiian 
History. Translated by Mary Kawena Pukui. 
Bishop Museum Press, Honolulu. 183 pp. 
Macdonald, G. A., and J. P. Eaton. Hawaiian 
Volcanoes during 1955. U. S. Geol. Survey 
Bull. 1171. 170 pp. 
— — — and C. K. Wentworth. 1952. The 
Kona earthquake of August 21, 1951, and its 
aftershocks. Pacific Sci. 6:269-287. 
