Support for the Giant Wave Hypothesis: evidence from submerged terraces off Lanai, Hawaii

Webster, Jody M., Clague, David A., and Braga, Juan Carlos (2006) Support for the Giant Wave Hypothesis: evidence from submerged terraces off Lanai, Hawaii. International Journal of Earth Sciences, 96 (3). pp. 517-524.

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The origin of subaerial coral conglomerate deposits on the Hawaiian islands of Lanai and Molokai is controversial, primarily because these deposits are difficult to interpret and the vertical motion of these islands is poorly constrained. Based on bathymetry, dive observations, sedimentary and radiocarbon data from coralline algal dominated deposits from two submerged terraces at –150 and –230 m off Lanai, Lanai has experienced relatively little vertical movement over the last 30 ka. Using internally consistent age versus depth relationships, paleowater depths, and published sea level data, we estimate that Lanai has experienced maximum rates of uplift of 0.1 m/kyr or subsidence of 0.4 m/kyr over this period. Our analysis of possible uplift mechanisms, published geophysical, numerical modelling, and recent tide data suggests that this is also the maximum uplift rate for the last several hundred thousand years. Taken together these data support the interpretation that coral conglomerates at elevations higher than +35 m on Lanai are tsunami deposits with a minimum wave run up > 170 m, rather than shoreline deposits formed during the last two interglacials, then uplifted to their present elevations.

Item ID: 1024
Item Type: Article (Research - C1)
ISSN: 1437-3262
Keywords: Hawaii, Lanai, submerged reef terraces, subaerial coral conglomerates, tsunami
Date Deposited: 03 Nov 2006
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040310 Sedimentology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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