On January 14 in 1987, a big earthquake occurred in the northern part of the Hidaka Mountains. According to the report of Japan Meteorological Agency (JMA), the seismic magnitude was 7.1, the maximum intensity as high as V was reported at Kushiro, intensity IV were reported at Obihiro, Urakawa, Hiroo, Morioka, Hachinohe, Nemuro and Tomakomai and the seismic intensity at Muroran was Ⅲ. Immediately after the earthquake, about 6,000 questionnaire sheets were delivered to the persons in Muroran City and Noboribetsu City. It makes an estimate of the intensity distribution in detail. The results are following as; (1) The seismic intensity of Muroran and Noboribetsu area was determined as 3.5. (2) The seismic microzoning map was shown in each area (every town). (3) The maps show that seismic intensities depend on the subsurface structure at sites ; for example, the intensities in unstable places of alluvial formation are, on an average, about 0.4 ～ 0.5 more than those on relatively stable places of The Tertiary or igneous rock. (4) The seismic microzoning maps on Muroran City show the almost same result at the case of the 1968 Tokachioki earthquake.
アンケート調査による日高山脈北部地震 (1987.1.14) の室蘭・登別市域の震度分布
kiyo41_rikou_pp39-59.pdf
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