QSR

The development of a diatom-based transfer function along the Pacific coast of eastern Hokkaido , northern Japan -an aid in paleoseismic studies of the Kuril subduction zone

Yuki Sawai^a, Benjamin P. Horton^b and Tamotsu Nagumo^c

^aActive Fault Research Center, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Site C7 1-1-1 Higashi, Tsukuba 305-8567, Japan
^bDepartment of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104-6316, USA
^cDepartment of Biology, The Nippon Dental University, Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan

Received 31 March 2003; accepted 12 May 2004. Available online 21 August 2004 .

Abstract

This paper provides a dataset to develop a diatom-based transfer function, which is applicable to paleoseismic studies at southwestern Kuril subduction zone, northern Japan . Modern diatom samples were collected from five transects from saltmarshes of Lakes Akkeshi and Onnetoh along the Pacific coast of eastern Hokkaido . The relationships between diatom species and environmental variables were elucidated by canonical correspondence analysis (CCA) and partial CCAs. Partial CCAs associated with Monte Carlo permutation tests show that elevation accounts for a significant portion of the total variance in the diatom data. Therefore, statistically significant transfer functions quantifying the relationship between modern diatom assemblages and elevation were developed using weighted averaging partial least squares and applied to fossil diatom assemblages from Lake Onnetoh . The reconstructed curve of elevations contains five emergence and four submergence events and the transfer functions calculated the amplitude of four of the emergence events to be at least 1 m. The results are consistent with paleoecological data produced by previous studies. If these events represent uplift associated with interplate earthquake and subsidence during an interseismic period along the Kuril subduction zone, transfer functions of eastern Hokkaido can contribute to reconstruction of the recurrence intervals and the amplitude of earthquakes.