The Kohala survey shows the headwall of the Polulu giant landslide (Moore et al., 1989, 1994) on the northeast side of Kohala Volcano on Hawaii. On land, the landslide is bounded to the south by the famous Waipio Valley and to the north by the Pololu Valley. Offshore, the landslide is not evident as it is buried beneath carbonate terrace deposits (Clague et al., 1998).
There are two prominent terraces present, with the shallower one about 400 meters deep and dating from about 125,000 years ago, and the deeper and older terrace about 1,150 meters deep and dating from about 425,000 years ago (Moore and Clague, 1992). These reefs are constructed on top of the slide debris, indicating that the slide dates from the active shield-building stage of activity of Kohala Volcano, which ended at about this time. In addition, the offshore data suggest that the slide did not move very far, as a cluster of volcanic cones occur in the path that the slide is thought to have traveled.
The Pololu slide appears to have been a slump, like the Hilina fault system on Kilauea, but one that never failed catastrophically. The shallowest part of the carbonate terrace is incised by submarine canyons. However, in contrast to the canyons north of Moloka`i, these canyons appear to have formed below sea level and to have eroded into the carbonate terraces. Many of the canyons begin mid-slope and become more subtle downslope. We think that these canyons formed from submarine fresh water flow that dissolved the canyons in the carbonate terraces.
Survey Detail
Data locations listed below, or click on name to download.
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 Oblique view 1 |
 Oblique view 2 |
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| Index Map | Haleakala | Hilo | Kohala | Loihi | Mahukona | Moloka`i | Ni`ihau | Papa`u | Puna Ridge |