Exploration for the history of large earthquake along

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This study aims to reveal the history of huge earthquakes along the Nankai Trough since 5,000 years BP using raised calcareous assemblages adhering to coastal rocks in and around Cape Muroto, southwestern Japan. I collected several boring cores from large assemblages and made an analysis on sedimentation and age of them in fiscal 1977 and 1998. In fiscal 1999, I made isochron map on the growth process of raised assemblages base on the analysis done in the last two years. The result is that stable phase in relative sea level had lasted since 4500 BP through 2700BP and since 2700BP through 1750BP at the present elevation of 9m and 6.7m respectively. Uplift of Cape Muroto since 5000BP is attributed to the combination of intra-plate earthquake and inter-plate earthquake, though accumulative uplift by intra-plate, which occurred at the interval of 2000 years, would be dominant I found some organisms which should have lived in separate tidal range such as coral or calcareous algae in the boring cores. I could know the timings of inter-plate earthquakes through the analysis on age and species of such organisms. The possibility would be handed over to the next project.