Naomi Murakoshi

Erosion and Deposition by the 2004 Indian Ocean Tsunami in Phuket and Phang-nga Provinces, Thailand

Abstract The devastating December 26, 2004, tsunami produced abundant geologic effects along the Andaman coast of Thailand. The tsunami inundated the numerous sandy beaches and flowed over the adjacent aeolian dunes. On some of the dunes, the tsunami scoured circular holes 10–30 cm in diameter, and in its waning phases, it coated the holes with mud. The tsunami locally deposited a sand sheet that ranged from 0–30 cm in thickness, with an average thickness of approximately 10 cm. Sedimentary structures within the sand sheet include ripples from inflow and outflow, graded bedding, parallel lamination, and double-layered deposits. Erosion, locally severe, affected sand beaches and tidal inlets. We use these erosional and depositional features to infer the main processes that acted during inundation from the tsunami.

Estuarine, barrier-island to strand-plain sequence and related ravinement surface developed during the last interglacial in the Paleo-Tokyo Bay, Japan

Abstract Recognition of sequence boundaries and transgressive surfaces (i.e. ravinement surfaces, RS) is now known to be of great importance in stratigraphy. The sedimentary features of deposits immediately above a transgressive surface are well exposed in the Upper Pleistocene Kioroshi Formation of the Kanto Plain in central Japan. The formation comprises mainly coastal and shallow-marine deposits (estuarine, barrier-island and the strand-plain systems) which accumulated along a wavedominated coast in the Late Pleistocene, i.e., the last interglacial to last glacial period. The Kioroshi Formation is bounded above and below by sequence boundaries that formed in the lowstand periods correlative to the glacial periods of oxygen isotope stages 4 and 6, respectively. A significant transgressive surface that was formed by landward migration of barrier islands during the transgressive interval, the ravinement surface (RS), is found within the deposits of the upper shelf environment. This ravinement surface is characterized by the exotic nature of the overlying sediment veneer (pebbles, shells and scattered mud clasts) which is poorly sorted. The RS shows a very flattened erosional surface in the shore-parallel sense, and the gradient of the surface in shore-normal sense is calculated as 0.0021, where the syndepositional tectonic movement is revised. The RS commonly cuts through the lower sequence boundary. However, in the places where the river or tidal channel valleys incised, the valley-filling sediment shows a deepening-upward sequence recognized as a transgressive systems tract and the RS can be clearly distinguished from the lower sequence boundary.

Effects of Global Warming on the Phenological Observation in Japan

Strong correlations were found between blooming dates and meteorological factors. On the basis of on these correlations, predictive maps of blooming dates in the Japanese Islands were proposed for each case of 1°C, 2°C and 3°C of monthly mean temperature warming. The correlation was tested for the blooming dates of Prunus yedoensis, Prunus Munie, Camellia japonica, Taraxacum sp., Rhododendron Kaempferi, Wistaria floribunda, Lespedeza bicolor, Hydrangea macrophylla,Lagerstroemia indica, Miscanthus sinensis, etc., using the data on monthly mean temperatures from 102 meteorological stations in Japan for the period 1953–1990. Simple and multiple regression analyses were used for the correlation.