HR: 15:25h
AN: OS13B-08 INVITED    [Abstracts]
TI: Characterization of Recent Extreme Wave Deposits, SE Hawaii
AU: * Richmond, B M
EM: brichmond@usgs.gov
AF: U.S. Geological Survey, Pacific Science Center 400 Natural Bridges Drive, Santa Cruz, CA 95060, United States
AU: Jaffe, B E
EM: bjaffe@usgs.gov
AF: U.S. Geological Survey, Pacific Science Center 400 Natural Bridges Drive, Santa Cruz, CA 95060, United States
AU: Gelfenbaum, G
EM: ggelfenbaum@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd. MS999, Menlo Park, CA 94025, United States
AU: Dudley, W C
EM: dudley@hawaii.edu
AF: University of Hawaii at Hilo, 200 W. Kawili St., Hilo, HI 96720, United States
AU: Watt, S G
EM: swatt@usgs.gov
AF: U.S. Geological Survey, Pacific Science Center 400 Natural Bridges Drive, Santa Cruz, CA 95060, United States
AB: Deposits formed by extreme waves, such as those from large swell, storms, or tsunamis, leave a sedimentary record that provides clues to the type and characteristics of the depositional event. The island of Hawaii has been impacted by both storms and tsunamis over the last century and is an ideal location to study deposits produced by such events. Recent basalt flows along the southeastern coast of the island of Hawaii are mantled by several types of extreme wave deposits. These deposits can be characterized as: 1) Scattered gravel fields and occasional thin sand sheets that extend up to several hundred meters inland. The gravel ranges in size up to nearly 4 m (a-axis) and consists of both angular (common) and rounded (rare) basalt fragments with occasional marine debris such as coral and shell material. The gravel field deposits are attributed to deposition from the locally generated 1975 Kalapana tsunami. 2) Shore-parallel ridges composed mostly of basalt sand and/or gravel with variable amounts of carbonate detritus. The ridges range in elevation from about 1 to 3 m and are tens of m wide. They occur either on elevated basalt platforms (1.0-6.5 m high) where the ridges are set back from the cliff edge and separated from the edge by a narrow, sediment-free zone, or, as a supratidal extension of a pocket beach. No major tsunamis have impacted this area since November 1975 and there is photographic evidence that indicates the ridges have formed since the 1975 tsunami and therefore are the product of wave deposition during storms or long distance swell events. Results from this study provide useful information in differentiating between storm and tsunami deposits in coarse clastic sediment.
DE: 4558 Sediment transport (1862)
DE: 4564 Tsunamis and storm surges
DE: 4863 Sedimentation (1861)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting