A 53.88m sediment core (TKN-2004) taken from the Takano Formation, Nagano Prefecture in central Japan, consists mostly of homogenous clayey silt, including numerous beds of primary fallout tephra. On the basis of the stratigraphy, petrography, and chemistry of volcanic glass shards, hornblende, and orthopyroxene measured by microprobe (EDS) analyses, 15 tephra beds can be correlated to the Aso-2, Aso-3, Nanko-II, Nanko-III, SK, Tt-D, Ata, Aso-ABCD, On-Pm1, K-Tz, On-Kt, Aso-4, On-Ng, Tt-E, and BW1466 tephra beds in ascending order. Using the 4 time marker tephra beds-namely, Aso-2 (146ka), Aso-3 (133ka), Aso-4 (88ka), and BW1466 (38.5ka)-as the controlling points, depositional ages of other 17 marker tephra beds in the TKN-2004 core can be calculated, postulating that sedimentation rate is constant between the controlling points. The ages of marker tephra beds in the TKN-2004 core estimated by this method are very consistent with the identification of the oxygen isotope stages based on the palynological study of the Takano Formation and the total organic carbon content profile of the TKN-2004 core. Consequently the TKN-2004 core sample can provide not only a high-resolution record of the climate from MIS 6 to MIS 3, but also the standard stratigraphy of the widespread tephra beds of the middle to upper Pleistocene in southwest to central Japan.

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The sequence stratigraphy of the Plio-Pleistocene Tsunozu Formation (incised valley fills) was reconstructed based on detailed outcrop studies in an area where excellent exposures are available. The studied interval contains several depositional sequences, composed of bayhead delta and bay deposits forming a retrogradational sequence set. Lateral continuity of the bay deposits differs between the lower and upper sequences. The bay deposits in the lower sequences are localized, whereas those in the upper sequences are laterally extensive. The predominance of bay deposits in the upper sequences can be explained by differences in the width of the incised valley. In the narrow valley phase when the lower sequences were accumulated, fluvial deposition was concentrated in a restricted area, leading to build-up of fluvial sands in the main part of the valley even during sea-level rise. This process confined the distribution of the bay deposits to fluvial sand lobes. In contrast, fluvial sand accumulation was sparse in the wider parts of the valley, resulting in the predominance of bay facies in the upper sequences.

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Sedimentary facies and molluscan fauna of the lower to middle Pleistocene Kitaarima Formation in the eastern Kitaarima area, southeastern Shimabara Peninsula, northwestern Kyushu, were studied. Depositional environments of eight sedimentary facies which have been recognized in this study are respectively interpreted as tidal flats (I), tidal channels (IIa, b), river mouths (IIIa, b, c), and central part of bay (IVa, b). The sedimentary succession shows at least two sedimentary cycles. Three molluscan assemblages (A, B, and C) are recognized. Assemblage A is characterized by Potamocorbula cf. laevis, and is found in the sedimentary facies IIb. Assemblage G is mainly composed of Volachlamys hirasei, Crassostrea ariakensis, and Scapharca kagoshimensis, and is recognized in the sedimentary facies IIa and IIb. Assemblage S, found in sedimentary faces IVb, consists of many species as Oliva mustelina, Indomitrella yabei, Abrina lunella, and Cantharus sp. Additionally, five species known as subendemic species of the Ariake Sea are found. Among them, V. hirasei and Meropesta capillacea are the second oldest records, next to one from the lower Pleistocene Kazusa Formation in southwestern Shimabara Peninsula, and C. ariakensis is the oldest. However, the other species, Inquisitor pseudoprincipalis and Barnea dilatata, appeared in the Pliocene shelf sediments. Thus, I. pseudoprincipalis and B. dilatata are shallow warm water species, and it is reasonable to suppose that they do not have roots in the Chinese Continental coast.

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The Middle Pleistocene “hpm1” tephra layer of the Lowermost Daisen Tephra Formation has been found over the northern Kinki District. Examinations of the hornblende chemistry and the heavy mineral assemblage of the tephra revealed that Kumiyama volcanic ash layer and P5 or P6 volcanic ash layer can be correlated to “hpm1”, respectively. The results indicate that “hpm1” is potentially a widespread tephra and useful as a datum plane in the late Middle Pleistocene at ca. 230ka.

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This paper reviews the late Holocene sea-level changes associated with plate-boundary earthquakes along the Pacific coast of eastern Hokkaido.
This tectonically active area, where the Pacific plate subducts at 8cm/yr, has been steadily subsiding at the fast rate of 8-9mm/yr in the 20th century as recorded by tide gauges. Pleistocene marine terraces, however, imply 0.3-0.5mm/yr of net uplift during the past 125,000 years. In addition, an oyster bank which is indicative of the past mean tidal level shows nearly null net vertical movement during the past 6,000years. To reconcile these opposite coastal movements, coastal uplift events were needed.
Repetition of coastal uplift was marked by emergence events (sea-level fall) in three coastal marshes (Akkeshi, Hichirippu, and Onnetoh). The sea-level fall events provided estuary-wide stratigraphic contacts, and the stratigraphic contacts clearly separate the diatom and the plant macrofossil dominance : marine-brackish taxa in lower mud and freshwater taxa in upper peat. Three of the sea-level fall events were attributed to coastal uplift based on the following three criteria ; (1) widespread peat-over-mud contact, (2) coincidence of tsunami deposits, and (3) regional synchroneity of sea-level fall events. Radiocarbon ages tephrochronology show the three events occurred ∼1,400-1,000, ∼800-300, and ∼300 cal yrs BP.
The coastal uplift is probably generated by infrequent decadal seismic slip, although such large-scale slips have not been recorded in the plate-boundary earthquake cycle of the 19th and 20th centuries in the Kuril trench. Diatom-based transfer functions for sea-level reconstructions, which are applied to deposits just below and above the 17th-century tsunami deposits, show several decimeters of preseismic subsidence, no coseismic change, and at least 1m of postseismic uplift. The amplitude of postseismic uplift is consistent with 5m of aseismic slip of a deeper part than the seismogenic zone in the Kuril trench. Such decadal postseismic slips in a deeper part than the seismogenic zone have been observed in unusually large plate-boundary earthquakes in Chile and Alaska. I concluded that Holocene coastal uplift along the Pacific coast of eastern Hokkaido was triggered by an unusually large plate-boundary earthquake in the Kuril trench.

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