HR: 1330h
AN: V22C-0601    [PDF]
TI: Internal Structure of the West Submarine Flanks of Mauna Loa and Hualalai, Hawaii Island: investigation of ROV KAIKO and Manned Submersible SHINKAI
AU: * YOKOSE, H
EM: yokose@sci.kumamoto-u.ac.jp
AB: Submersible-based exploration of basaltic rocks west flank of the Hawaii Island, mostly at 2000 to 5000 m depths, was a focus of Japan USA joint research during two cruises by the JAMSTEC in 2001-02. The observations from submersibles and samples recovered are summarized, based on the twelve recent submersible dives and numerous newly obtained samples from deep submarine flanks of Hualalai and Mauna Loa Topographic nature of the studied area are categorized using high-resolution bathymetric data obtained during the cruses and are very effective for deciphering the sequence of landslides. Because the west of Hawaii Island is lee side having a little rain, topographic characteristics of landslide deposits are preserved without buried by material of the later subaerial erosion process. Submarine geological map of the west flank of Hawaii Island has been revised on the basis of these investigations. Major difference between maps proposed previously and this work is twofold. The first is the submarine flank of this area consists mainly of pillow lavas. This is contrastive to the Nuuanu landslide and Hilina slump regions in which hyaloclastite and fragmental debris are dominated. The debris avalanche deposits are prevailing only in the lower submarine slope. The second is the sequence of landslide events. Base on the topographic and geologic investigations major landslide events can be redefined in the sequence from early to late: South Kona Slide 1(South Kona slump and Ka Lae west debris-avalanche), South Kona Slide 2 (South Kona slide), North Kona Slump (North Kona slide + Alika 1 debris-avalanche), Ka Lae slump (newly defined), Ka Lae debris-avalanche (Ka Lae East debris-avalanche), Alika debris-avalanche (Alika 2 debris-avalanche). It is concluded that these slope failures were probably result in the rift propagation rather than instability of the slope itself which made of unstable fragmental lavas. Therefore, the pillow lava model is more suitable for present case. However, the fragmental lava model is also correct in other case, such as Nuuanu landslide and Hilina slump. Each cross section can not represent as a general model, because the growth conditions differ in the directions.
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3045 Seafloor morphology and bottom photography
DE: 8015 Local crustal structure
DE: 8400 VOLCANOLOGY
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting