Nuuanu Landslide (scientific objectives)

In the summers of 1998, 1999 and 2001 the Japan Marine Science and Technology Center (JAMSTEC) vessels Yokosuka and Kairei utilized multibeam bathymetric mapping systems (SeaBeam 2100) and GPS navigation to produce a detailed bathymetric map of the Nuuanu landslide. This 220-km-long underwater landslide northeast of Oahu is among the world's largest landslide. This map is a marked advance over previous contour maps of the region and is the most detailed regional map yet made of the landslide. It depicts the individual blocks in the landslide down to a few hundred meters in length, and is an important resource in conducting studies of the landslide. The map was utilized in 1999 in siting four Shinkai dives on three of the largest blocks in the landslide coast (Clague et al., 2002, Yokose, 2002; Moore and Clague, 2002).

The purpose of the 2002 diving program is to examine unsampled landslide blocks at both the proximal and distal ends of the landslide. These will include the first discrete block, 60 km off the Oahu coast and the most far-traveled large block 160 km off the coast. The proximal block is 12 x 8 km in size and the distal block is 10 X 4 km in size and 700 meters in height. The distal block has apparently moved out 90 km from its place of origin and during the last 60 km, it has slid 200 m uphill from the axis of the Hawaiian Deep onto the Hawaiian Arch, because of its momentum. The proposed dives will provide information on blocks distributed over much of the length of the landslide. From the samples we can compare the compositional range of lavas from head to toe of the landslide, and whether the blocks contain lava erupted on land or below sea level. We can then understand better the nature of the terrain that gave birth to the landslide. Such information can refine out model of landslide structure and movement, which in turn may provide new insights into the generation of tsunamis associated with the landslide (Satake et al, 2002).

References

Clague, D. A., J. G. Moore, A. S. Davis, 2002, Volcanic breccia and hyaloclastite in blocks from the Nuuanu and Wailau Landslides, Hawaii: American Geophysical Union Monograph 128, p. 279-296.

Moore, J. G. and D. A. Clague, 2002, Mapping of the Nuuanu and Wailau landslides in Hawaii: Hawaiian Volcanoes, American Geophysical Union Monograph 128, p. 223-244.

Satake, K., J. R. Smith, K. Shinozaki, 2002, Three-dimension reconstruction and tsunami model of the Nuuanu and Wailau giant landslides, Hawaii: Hawaiian Volcanoes, American Geophysical Union Monograph 128, p. 333-346.

Yokose, H, 2002, Landslides on the windward flanks of Oahu and Molokai, Hawaii: SHINKAI 6500 submersible investigations: Hawaiian Volcanoes, American Geophysical Union Monograph 128, p. 245-262.