Systematic and detailed information on the local geological and ground conditions plays an important role in nationwide disaster-mitigation systems. For that purpose we developed the "Japan Engineering Geomorphologic Classification Map (JEGM)", which is a nationwide GIS-based map containing the attributes of geomorphologic unit, subsurface geology, slope gradient, and relief energy in approximately 380,000 grid cells of 1 × 1 km each in size across the country. In order to test whether our geomorphologically-defined units accurately reflect the ground conditions, a site amplification evaluation and susceptibility assessment for liquefaction are necessary to be performed. In this paper, we investigate the relationship between the proposed geomorphologic classification unit of our system and the site amplification factors (PGA, PGV, and the response spectra) of 77 JMA sites countrywide, determined from 3,990 strong motion records by previous studies. Then, we calculate the average and variance of the site amplification factors at every geomorphologic unit. Our new geomorphologic classification system shows a smaller variance at each unit compared with previous classifications. Developed JEGM will be allowed detailed estimation of the site amplification factor nationwide, to be used for the calculation for near real-time ground shaking maps.
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