考古地磁気法による古地震の年代推定の研究 [in Japanese] Archaeomagnetic dating of paleoearthquakes [in Japanese]
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For investigating paleoearthquakes, dating is important. Generally the<SUP>14</SUP>C dating method is employed to date earthquakes that have occurred during the historical and/or the archaeological ages. The archaeomagnetic dating method can also be employed, which uses the remanent magnetization of objects and geomagnetic secular changes. The archaeomagnetic dating method is practical in Japan because detailed secular variations in the geomagnetic field during the past 2000 years have been clarified by Hirooka (1971), etc. In this study, we discuss the archaeomagnetic dating conducted in two regions: the Atotsugawa active fault region in Gifu Prefecture, where the sediment near the main fault zone was studied and the archaeological Ishizuka site of Takaoka city in Toyama Prefecture, where the sand boiling was studied.<BR>In the Atotsugawa active fault region, archaeomagnetic dating was successfully adopted and it yielded an age of A. D.1850-1900, which corresponds to the earthquake of“ Ansei jishin” that occurred in A. D.1858. At the Ishizuka archaeological site, archaeomagnetic dating on sand boiling yielded an age of A. D.863the year in which“ Jogan jishin” occurred around Toyama Prefecture.<BR>We conclude that archaeomagnetic dating is useful for the dating of active faults and further study on it is desirable.
- Active Fault Research
Active Fault Research 2007(27), 9-16, 2007
Japanese Society for Active Fault Studies