OS31A-0156
Sedimentological characteristics of the July 17, 2006 tsunami in South Java
With the help of tsunami deposits, tsunami run-up characteristics and tsunami depositional processes can be inferred in order to understand tsunami as a geological process, but also to recognise tsunami deposits within sedimentary deposits of different sedimentary environments. Unique features of such deposits have not been identified to distinguish them from, for example, storm or other deposits indicating high-energy regimes. The 17 July 2006 tsunami was caused 200 km off the south coast of Java by a ca. 10 km deep Mw 7.8 earthquake at 15:19 local time and struck the coast 20 minutes later. Depending on the geometry of coast and beaches, run- up heights exceeded 20 m at headlands, and were significantly lower, less than 2 m, along many straight beaches. We measured the maximum run-up distance of 700 m at Bunton Beach near Cilacap. Quasi-linear debris accumulations document up to three subsequent waves of decreasing inundation and run-up. We surveyed beaches along the central south coast of Java between Pangandaran and Parangtritis south of Yogyakarta and sampled the tsunami deposits. The analysed deposits taper landward and often have erosive bases. Bottom layers may contain soil rip-up clasts incorporated from inundated agricultural fields. Sedimentary structures include small current ripples documenting backwash flow in morphological depressions. Deposits consist of up to 5 layers of medium and fine sand which display a weakly developed fining inland trend. Individual layers may be graded. Deconvolution of grain-size distributions revealed that the most deposits were derived from at least two well sorted, normal grain populations, the modes of which differ by up to 1 phi unit. Both grain populations were most likely derived from well sorted beach and near shore sands. Benthic formaminifera deposited with the sands indicate shallow marine environments of sediment entrainment.
OS31A-0157
Manifestations of the 15.11.2006 Kuril Tsunami Consequences on the Central Kuril Islands: the Reconstruction Events of the Destruction of Soil and Coastal Vegetation.
The investigation of the Central Kuril Islands (Simushir, Urup, Ketoy) coast was performance by the field survey for the Institute of Marine Geology and Geophysics FEB RAS (Yuzhno-Sakhalinsk) on the vessel "Iskatel-4" to be able find different deposits of the devastating tsunami waves influence on soil and vegetation. There were average run-up heights and inundation areas (tsunami flooding zones): h=6-9 m and 40-60 m (Ketoy); h=7-19 m and 80-300 m (Simushir). The field observation showed destruction of the soil layer. The estimation of water stream velocity for the hydraulic destruction of rocks enabled to receive velocity average mean for the water stream during tsunami dynamic inundation which may be in interval of velocities near 30 -50 m/sec. Field observations of coastal plants in tsunami inundation zones on Urup, Simushir and Ketoy Islands enabled us to recognize the character of destructive influence of tsunami waves to plant structure and essential signs of micro-phytocenoses for ecotopes at different distances from the coastline. Various plant species and vital morphes were found to indicate different reaction on sea waves. The investigation results showed that selected plant species demonstrate the strong response to tsunami wave inundation. We found that the most sensitive species to mechanical and physical- chemical tsunami impact are: Pinus pumila (Pall.) Regel and Phyllodoce aleutica (Spreng.) A. Heller. The character of plant damage shows in breaking of skeletal axes, infringement of root systems, and leaf dying. These findings allow us to use the species as effective indicators of tsunami flooding zone and estimation of tsunami run-up heights. Fulfilled analyzes let us to reconstruct possible events when tsunami hits to coast with specific shore morphology. The wave front at the slightly sloping coast (from coastline to first terrace) is characterized by uniform growth of water level when water moves away soil material (no more 2-3 cm) and micro- phytocenoses is maintaining the stability. During impact to steep dune slopes, tsunami wave generates violent horizontal streams which hit to sea-bank with velocities in order to 30m/sec and lead to considerable destructions of soil layer on the depth 30-35cm and structure damage of vegetation.
OS31A-0158
Tsunami Erosion: Geomorphology Before and After the 15 Nov 2006 Tsunami in the Middle Kuril Islands, Russia
Because the 15 Nov 2006 middle Kuril Island earthquake (Mw 8.3) and tsunami occurred between two field expeditions of the Kuril Biocomplexity Project, we have detailed topographic profiles and photographs from 3 months before and 9 months after the event. Thus, we are in the position to define tsunami-induced changes in coastal geomorphology both quantitatively and qualitatively. The locations where we conducted our surveys varied in the type of coastline (defined by the width, geomorphology and sediment type of the coastal plain), and the local size of the tsunami (defined by runup and inundation). The change from 2006 to 2007 was most extreme in the sandy beach ridge plain of central Ainu Bay, Matua Island, which experienced a tsunami with 15-20 m runup and 300-400 m inundation. Topographic profiles measured in 2006 and re-measured in 2007 show that the beach was eroded landward 25-50 m, with entire beach ridges removed or reduced in size, and troughs between ridge deepened. Farther landward, there are many zones of soil stripping, both large and small— the tsunami exploited rodent networks and cinder layers to flay the surface. There are also scours associated with concentrated outflow. Erosion was about as extensive as deposition— within 10s of m of inundation distance and meters of runup elevation). However, the volume of sediment eroded is an order of magnitude greater than the volume of sediment deposited onland. In areas with high runup (10-20 m) and narrow rocky beaches (eastern Matua Island and parts of Dushnaya Bay, Simushir Island), patchy to extensive erosion occurred over almost all of the inundation distance up to a few meters below maximum runup. Erosion was evinced by trim lines, where soil and vegetation were stripped to an approximately uniform elevation, and by other forms of soil removal. Soil scouring also commonly appeared as scalloped "bite marks" along the beach edge or edges of stream channels. Of studied sites, erosion was minimal where runup was less than 10 m (central Dushnaya Bay, Simushir Island). In general, changes were subtle and present mainly near the shoreline. Examples of erosion in this location are back-beach cliff retreat, surficial sediment removal on sand dunes (which lack coherent soils), and small-scale scouring associated with focused water withdrawal.
OS31A-0159
Aperiodic recurrence of Holocene tsunamis in eastern Hokkaido, Japan
Sandy deposits provide evidence for 15 tsunamis between 200 and 6,000 years ago at a muddy lagoon (Mochirippu) and a peaty beach-ridge plain (Kiritappu) 15 km apart along the Pacific coast of eastern Hokkaido. Additional sand beds at the lagoon probably represent historical tsunamis of A.D. 1843 and 1894. We observed the sequences of sandy deposits in continuous slices 2-4 m deep. Some of the deposits consist of just a single sand bed, while others contain multiple units of sand, mud, and plant detritus. We bracketed the ages of most the inferred tsunamis by a historical tephra (B-Tm: AD 947) and AMS radiocarbon dating of detritus from pre- and post-tsunami beds of mud and peat. The main materials dated are seeds and leaves at the lagoon and charcoal from the beach-ridge plain. Tsunami dates computed from the bracketing ages commonly have uncertainties, at two standard deviations, that span two to four sidereal centuries. Within these uncertainties the inferred sequence of 15 prehistoric tsunamis at the lagoon, beginning almost 6,000 years ago, can be matched tsunami by tsunami with the inferred history at the beach-ridge plain 15 km away. The intervals between the inferred tsunamis average nearly 400 years and range from as little as a century to as much as a millennium.
OS31A-0160
Anomalous sand deposit associated with evidence of late Holocene uplift near Bremerton, Washington
The origins of a puzzling sand unit at the head of Sinclair Inlet likely include a Puget Sound tsunami and its return flow but may also include sand volcanoes, debris flows, or both.. The inlet, a branch of Puget Sound 22 km west of Seattle, contains at its head an intertidal mudflat that is fringed by partly urbanized tidal marshes and alder swamps. Cores and pits in these remnant wetlands reveal an abrupt upward change from tidal flats to freshwater forest that probably resulted from uplift during the Seattle fault earthquake of A.D. 900-930 or during slip of similar age on the Tacoma fault. The puzzling sand unit formed at or about the time of this uplift. The unit consists of silty fine sand commonly 1 m in thickess. It has a sharp contact with shelly mudflat deposits below and a sharp to gradational contact with overlying peat. The lower part of this peat contains the growth-position roots of western red cedar (Thuja placata), and the upper part forms the soil of modern salt marshes. We found the sand unit, 1.1 m thick in areas, along 0.5 km of the upper inlet's shoreline, beneath modern tidal marshes and alder swamps. The unit contains at least three parts: a basal subunit that fines upward from medium and coarse sand to fine sand and silt; a thin (less than 1 cm thick) clay bed, commonly with flame structures; and a capping subunit up to 50 cm thick that is dominated by silty fine to medium sand but which also contains pebbles derived from rock and glacial outwash. Preliminary diatom analysis shows the unit contains diatoms from a brackish environment. A possibly related sand unit lies 0.8 km inland, up the valley of Gorst Creek. Its thickness is in the range 0.2-1.0 m as observed thus far in creek banks and in pits at a nearby park. Unlike the sand that borders the inlet, it contains trough cross-bedding. We are investigating the relationship between this deposit and the silty sand deposit in the tide flats. Preliminary diatom analysis did not find any diatoms in this deposit.
OS31A-0161
Paleotsunamis in the Middle Kuril Islands -- Implications for a Seismic Gap (and in View of Recent Events)
Two great earthquakes occurred in the middle Kurils on 15 Nov 2006 (Mw 8.3) and 13 Jan 2007 (Mw 8.1). These earthquakes were the first big events in the short (< 300-yr) historical catalogue of this segment of the Kuril- Kamchatka subduction zone. This segment had been identified as a "seismic gap," and some researchers suggested that in this gap, seismic energy was low or released by slow-event earthquakes. In the framework of NSF-funded "Kuril Biocomplexity Project" (ARC-0508109, Ben Fitzhugh PI), we participated in international expeditions to the Kurils in summers of 2006 and 2007. One of many tasks of this project is paleoseismological research. During field work, the paleseismology team visited most Kuril islands, with a focus in 2007 on the middle Kurils, especially Simushir and Matua. We make multiple excavations along measured profiles and use marker tephra and radiocarbon dating for age control. Moreover, we now can compare paleotsunami deposits with deposits left last winter. Even before the great subduction-zone earthquake of 15 Nov 2006, we had field evidence of large prehistoric tsunamis in the middle Kuril Islands, indicating that this segment of the subduction zone has been seismically very active, comparable to other parts of the Kuril-Kamchatka system. Analysis of our data gave us preliminary tsunami frequencies of one (large) event every 50-300 years. On NE Simushir Island, paleotsunami deposits are present on marine terraces 3-20 meters high, with recurrence intervals of 200 years and less, the interval increasing with elevation and distance from shoreline. A number of these deposits are more extensive than the tsunami deposit from 15 Nov 2006. On S Matua Island, multiple paleotsunami deposits are present on marine terraces 4-15 meters high, with recurrence intervals of 300 years and less. A number of these deposits are from tsunamis comparable to or larger than that of 15 Nov 2006, which had its maximum expression on Matua. For a real estimation of earthquake and tsunami risk, we need to know paleoearthquake magnitude and its connection to tsunami intensity. The 2006 & 2007 events give us a unique opportunity to compare their tsunami height, inundation, and deposit parameters with the same from more ancient tsunamis. Using preliminary data from summer 2007, we estimate that tsunamis with intensity comparable to or bigger than 15 Nov 2006 have occurred in the middle Kurils every 250-500 years over the last few thousand years. It is reasonable to assign earthquakes greater than Mw 8 to these deposits.
OS31A-0162
Testing Numerical Tsunami Simulations Against the Inland Extents of Prehistoric Cascadia Tsunami Deposits at Cannon Beach, Oregon
Cannon Beach, Oregon faces extreme flooding hazards from future tsunamis generated by seafloor deformation during Cascadia megathrust earthquakes. Trans-Pacific tsunamis also threaten the City as exemplified by the 1964 Alaska tsunami that caused $230,000 of damage. Field mapping of prehistoric tsunami deposits and historical accounts of the 1964 tsunami are used to delineate the inland extents of past tsunamis for comparison with simulations performed with hydrodynamic models. The comparisons offer an empirical test of the credibility of numerical tsunami simulations used to develop evacuation routes and emergency response tactics for coastal communities in Oregon. Although the mapped extents of tsunami deposits can only define minimum estimates of runup and inundation, their inland limits can be used to identify simulations of tsunami inundation that underestimate real-world conditions, while increasing confidence in simulated inundations that meet or surpass the distribution of deposits left by tsunamis. At least three Cascadia tsunamis flooded the lower 1.4-1.6 km of the Ecola Creek valley within the last 1000 years. Estimates of the minimum inundation come from the mapped extents of three sand layers, all of which satisfy 8-9 out of 10 criteria that favor a tsunami origin. The sand layers exhibit physical attributes of beach sand, the presence of fossil brackish-marine diatoms, sharp or eroded lower contacts, landward-thinning trends, and 14C ages that are consistent with regional Cascadia earthquake and tsunami chronologies. The youngest deposit records flooding by the AD 1700 Cascadia tsunami. Age ranges for two earlier tsunamis span 520-800 and 910-980 cal yr BP. A fourth sand layer deposited by a large flood of Ecola Creek about 1.3 ka was distinguished from the three younger tsunami deposits because it shares attributes of sand from the active creek channel. The deposit lacks a landward-thinning trend and its distribution along the central axis of the valley is consistent with overbank flood deposits. The 1964 Alaska tsunami damaged City infrastructure and private property in Cannon Beach. Estimates of the inundation extent and runup elevation are inferred from eyewitness accounts released days after the March 27 tsunami. Maximum runup probably reached 5.8-6.1 m (MLLW) derived from estimates of tsunami flow depth at two sites. The inferred extent of inundation comes from reports of damage to Highway 101, extensive flooding of the business district and from extrapolation of flow depth estimates from eye-witness accounts.
OS31A-0163
Spatial evaluation of extreme wave deposits at Boca Olivia, Bonaire
A field mapping survey was conducted in early November, 2006, on the east coast of Bonaire, Netherlands Antilles, to help assess the potential risk of extreme wave events such as tsunamis and hurricanes in the Caribbean. The purpose of the survey was to determine the extent, spatial distribution, and origin of a sedimentary deposit occurring along the shoreline near Boca Olivia that ranges in size from sand to boulder. The deposit, which rests on an older Pleistocene reef platform now 4 to 7 m above present sea level, is presumed to have been formed by one or multiple extreme wave events over time. Approximately 600 boulders were measured in the deposit and georeferenced using GPS and high-resolution aerial photographs collected using a specially designed kite and digital camera system. In addition, topographic profile transects and geologic field observations were recorded. Boulders were mapped over nearly 5 km of coastline with most measurements concentrated along roughly 500 m in the Boca Olivia area. Boulders were observed up to 250 m inland from the shoreline and ranged in volume from 0.01 m3 to 74 m3. Approximately 80% of the boulders measured were smaller than 1.0 m3. The extent and spatial distribution of the deposit is being investigated to determine what type of extreme wave event or combination of events formed and modified the deposit over time. Mapping and analyzing spatial distributions of sedimentary deposits formed by past extreme wave events will help develop a greater understanding of the potential tsunami risk for the Caribbean and other parts of the world. http://pubs.usgs.gov/of/2006/1293/
OS31A-0164
The Role of Porosity in the Formation of Coastal Boulder Deposits - Hurricane Versus Tsunami
Coastal boulder deposits are a consequence of high-energy wave impacts, such as storms, hurricanes or tsunami. Distinguishing parameters between storm, hurricane and tsunami origin are distance of a deposit from the coast, boulder weight and inferred wave height. Formulas to calculate minimum wave heights of both storm and tsunami waves depend on accurate determination of boulder dimensions and lithology from the respective deposits. At present however, boulder porosity appears to be commonly neglected, leading to significant errors in determined bulk density, especially when boulders consist of reef or coral limestone. This limits precise calculations of wave heights and hampers a clear distinction between storm, hurricane and tsunami origin. Our study uses Archimedean and optical 3D-profilometry measurements for the determination of porosities and bulk densities of reef and coral limestone boulders from the islands of Aruba, Bonaire and Curaçao (ABC Islands, Netherlands Antilles). Due to the high porosities (up to 68 %) of the enclosed coral species, the weights of the reef rock boulders are as low as 20 % of previously calculated values. Hence minimum calculated heights both for tsunami and hurricane waves are smaller than previously proposed. We show that hurricane action appears to be the likely depositional mechanism for boulders on the ABC Islands, since 1) our calculations result in tsunami wave heights which do not permit the overtopping of coastal platforms on the ABC Islands, 2) boulder fields lie on the windward (eastern) sides of the islands, 3) recent hurricanes transported boulders up to 35 m3 and 4) the scarcity of tsunami events affecting the coasts of the ABC Islands compared to frequent impacts of tropical storms and hurricanes.
OS31A-0165
Marine Conglomerates of Agaete, Gran Canaria: A Tsunami Origin?
Of all the deposits interpreted as having been emplaced by a tsunami, those draping hillslopes at high elevations on ocean island volcanoes have been most controversial. Here, we describe such a deposit from the Canary Islands, whose minimal post-emergence subsidence or uplift makes interpretation of the deposits less difficult than in other examples. We present a preliminary interpretation of marine sediments located at Agaete, on the north-east coast of Gran Canaria. Previously interpreted as the result of a sea level high-stand, these have recently been re-interpreted as having been deposited by a volcanically-sourced tsunami. Our re-examination indicates that of the alternatives, a tsunami origin is the more likely. The deposit occurs in exposures of limited lateral extent, attached to the walls of the Agaete valley, and may be traced up to elevations of 188m a.s.l. and two kilometres inland from the coast. The deposits are up to 2m in thickness and contain a diverse assemblage of volcanic clasts, a marine fauna and large beach-rock boulders. Two sedimentary units are identified, separated by a calichified soil horizon. Analysis of microfossils has yielded a variety of marine organisms including gastropods, bivalves, sharks teeth, echinoid spines and foraminifera. The evidence supports a tsunami origin for a number of the beds, whereas others may be attributed to flash floods. Dating of the deposits has not yet been undertaken, but the Güimar lateral collapse on the neighbouring island of Tenerife (age range between 32 Ka and 1.75 Ma) has been cited as a possible source.
OS31A-0166
Three-dimensional simulation of a rock slide impact into water
The steep-sided fjords of western Norway have experienced numerous rock slide events that sometimes produced devastating tsunamis. The 1934 slide in the Tafjord region, when some 3 million cubic meters of rock plunged into the water, resulted in waves tens of meters high that destroyed two villages and killed about 40 people. A similarly dangerous situation exists now in Sunnylvsfjord, where a major expanding crack in the fjord wall at Aknes threatens to release from 5 to 40 million cubic meters of rock into the water. Such an event would devastate a large region, including the Geiranger Fjord, a UN World Heritage Site that is extremely popular with tourists. The Norwegian Government's Aknes-Tafjord project is responsible for studying and monitoring the potential slide area and for providing adequate warning to protect lives and property. In order to better understand tsunami generation from such events, we have performed 3-dimensional fully compressible hydrodynamical simulations of the impact of a large number of boulders from a steep slope into a deep body of water. We use the Los Alamos/SAIC adaptive-mesh-refined SAGE code, previously used to model tsunamis from underwater explosions, asteroid impacts, and both subaqueous and subaerial landslide sources. We find the interaction of boulders and water to be extremely turbulent and dissipative. It differs markedly from simulations of large-block impacts in similar geometry. No more than about 15% of the potential energy of the boulders ends up in the water wave. The rest of the energy goes into heating the boulders (and presumably fragmenting them, though that physics is not included) into generating winds, heating air and water, and generating turbulence. In the near field, the waves produced by the impact can be quite high -- tens of meters -- and have the potential to devastate coastlines at substantial distances from the site along a narrow fjord system.
OS31A-0167
Global Tsunami Database: Adding Geologic Deposits, Proxies, and Tools
A result of collaboration between NOAA's National Geophysical Data Center (NGDC) and the Cooperative Institute for Research in the Environmental Sciences (CIRES), the Global Tsunami Database includes instrumental records, human observations, and now, information inferred from the geologic record. Deep Ocean Assessment and Reporting of Tsunamis (DART) data, historical reports, and information gleaned from published tsunami deposit research build a multi-faceted view of tsunami hazards and their history around the world. Tsunami history provides clues to what might happen in the future, including frequency of occurrence and maximum wave heights. However, instrumental and written records commonly span too little time to reveal the full range of a region's tsunami hazard. The sedimentary deposits of tsunamis, identified with the aid of modern analogs, increasingly complement instrumental and human observations. By adding the component of tsunamis inferred from the geologic record, the Global Tsunami Database extends the record of tsunamis backward in time. Deposit locations, their estimated age and descriptions of the deposits themselves fill in the tsunami record. Tsunamis inferred from proxies, such as evidence for coseismic subsidence, are included to estimate recurrence intervals, but are flagged to highlight the absence of a physical deposit. Authors may submit their own descriptions and upload digital versions of publications. Users may sort by any populated field, including event, location, region, age of deposit, author, publication type (extract information from peer reviewed publications only, if you wish), grain size, composition, presence/absence of plant material. Users may find tsunami deposit references for a given location, event or author; search for particular properties of tsunami deposits; and even identify potential collaborators. Users may also download public-domain documents. Data and information may be viewed using tools designed to extract and display data from the Oracle database (selection forms, Web Map Services, and Web Feature Services). In addition, the historic tsunami archive (along with related earthquakes and volcanic eruptions) is available in KML (Keyhole Markup Language) format for use with Google Earth and similar geo-viewers.
OS31A-0168 INVITED
2004 South Asia tsunami left little record of its trace near Yala, southeastern Sri Lanka
The 2004 South Asia tsunami swept 1 km inland near Yala, on southeastern coast of Sri Lanka, yet little trace of its passage remains on land today. In contrast, 2004 deposits are preserved in lagoons near Hambantota and Rekawa, suggesting that the search for precursor events may be best served in shallow offshore settings. The coastline of Yala is fronted by a 10 m high coastal dune—the tsunami reached inland only through river- mouth gaps in the dune. Where the tsunami did exploit these gaps, however, it reached flow depths of more than 2.5 m inland, with velocities sufficient to mound debris (typically tree branches) in front of savanna trees. The savanna sits on a well developed sandy soil, yet no trace of tsunami inundation rests on that soil, even within tens of meters of the shoreline. Associated with rivers, and behind the coastal dune, several lagoons have formed in flooded river valleys. These lagoons are often sandy on the shoreward side, and become muddy on the landward side, a gradation that spans up to 1 km. Within this gradation, several sandy layers extend ~500 m inland and may represent marine inundations. The sandy layers are 5-15 cm thick, display lateral continuity at least on the order of 10s of meters, and appear to fine inland. These environments sit on a coastline that is strongly progradational. Lagoons and harbors known from 15th century accounts of this area are now dry and well inland. Ridge and swale topography dominates one site in northeastern Yala, also suggesting progradation, as does the presence of a 2500 YBP strand line some 500 m inland. Because of this, we suspect that a successful survey for ancient precursors to the 2004 event in this area will rely on identifying ancient lagoons, and thus will rely on a thorough understanding of the paleoenvironment of the area—a study which remains to be done.
OS31A-0169
Comparative Sedimentology of Recent and Ancient Tsunami Deposits in Sri Lanka
Sri Lankan coastal lagoon sediments contain two coarse sand deposits that are 3690 to 4570 radiocarbon years and display an analogous sedimentary signature to the 2004 tsunami deposit. Based on similar internal stratigraphy, grain size, composition, and age dating, these coarse sand deposits are interpreted to represent paleotsunami deposits. Sediment cores collected during two field campaigns to Karagan Lagoon, located on the southeastern coastline of Sri Lanka, were sampled along parallel and perpendicular transects to the coastline. The cores feature mud-dominated background sedimentation, interrupted by two coarse quartz sand layers with sharp erosive bases at approximately 50 to 80 cm depth. The layers are identified in 4 cores though the vertical thicknesses vary and the layers are not laterally continuous. Cores located closer to the lagoon mouth and the coastline in the direction from which the tsunami arrived contain more sand layers while cores farther away from the tsunami entry point have little to no tsunami deposits preserved. The 2004 tsunami layer is characterized by inversely graded, coarse quartz sand that fines slightly at the top of the core. Below the 2004 layer are approximately 30 cm of normal lagoon sedimentation consisting of organic-rich mud interspersed with brackish molluscs. From 50 to 80 cm, there are two deposits that interrupt the sequence of normal lagoon sedimentation and display similar internal stratigraphy in terms of grain size and type to the 2004 deposit. These deeper deposits are approximately 10 cm thick and are composed of inversely graded, coarse quartz sand intermixed with some silt and shell fragments. The 2004 tsunami deposit in Karagan Lagoon provides a modern analog by which we can interpret the deeper sand layers.
OS31A-0170
Characteristics of the turbidite units derived from the Alika debris avalanches on the submarine flanks of the island of Hawaii
Many giantic submarine landslides have been recognized around the Hawaiian Islands, and most of them are considered to be accompanied with giant tsunami. Core samples obtained from deep-sea floor are a useful record for estimating the frequency of giant submarine landslide. Hawever, correlation between turbidite deposits in the core sample and the giant submarine landslides are uncertain. In order to clarify the correlation, we have investigated phisical and chemical properties of the turbidites in the core samples obtained from the western Hawaiian deep. The turbidite were derived from the South Kona slide complex, which is well studied using facilities of submarine investigation (Yokose et al., 2004; Yokose and Kanamatsu, 2007), and are prevailing along the western Hawaiian deep. The three core samples were obtained during KR01-12 cruise in 2001: PC13, PC-14, and PC-15. The distance from the source region of each core, PC-13, PC-14, and PC-15, is approximately 120 km, 330 km, and 440km, respectively. The physical and chemical properties of the sediment in the core samples were analyzed (e.g., bulk composition, magnetic properties, grain size analysis, X-ray CT scan). We identify the Brunhes-Matsuyama boundary in the core samples of PC-14 and PC-15. Some dark brown thin layers are observed in the core samples by naked eyes. Some of them are corresponded to relatively coarser grained layers and higher magnetic susceptibility positions. However, many coarse-grains layers are rich in microfossils but sand grains. Some higher magnetic susceptibility positions are observed in the totally pelagic sediments. These factors are unlikely to indicate the turbidity layers. On the other hand, the bulk chemical composition of the sediments in the core samples are useful discriminator for a turbidits units. The sedimentary sequence bounded by the chemical composition is resembles to the Bouma sequence, especially those of Tb, Tc, Td, and Te (PC-13 has a hole sequence). As grain size distribution pattern and grain shape are different, pelagic sediments and the pelitic division of the turbidities unit are identifiable. Based on the above analysis, changes in the stratigraphic phase may corresponded to the distance from their source. The sedimentary units of Alika 1 debris avalanche deposit in PC-14 and Alika 2 debris avalanche units in PC14 and PC 15 are similar to sandy turbidite and muddy turbidite in a distal part of the landslide deposit, respectively. Based on the above investigation, we cannot define a landslide deposit by a thin sandy layer in the core sample. If a turbidite derived from a huge landslide, it should be composed of several layers as a units. Therefore, there are only two huge landslide events after Brunhes-Matsuyama boundary in the western part of the Hawaiian Islands.