STUDY ON THE EVIDENCE OF DISASTER AT THE ARCHAEOLOGICAL RUINS-EARTHQUAKE, VOLCAIC ERUPTION AND WAR

这里有许多遭受自然灾害的古代遗迹和遗迹。在考古遗址中寻找自然灾害的证据十分重要，计划开展自然科学与考古学的协同研究。我们研究了考古遗址的沙堤。为了确定过去地震中形成的沙堤的年代，发展了古磁法。通过对富山县石冢遗址沙堤的分析，我们成功地确定了8世纪的佐干地震。在富山湾附近的内出遗址发现的沙堤的年代为公元1450±50年，但富山县在15世纪没有地震的记录。经过我们的研究，发现了表明这次地震发生在内德遗址附近的古代文献。也就是说，磁场研究从考古遗址中清除了未知的古地震。经探地雷达探测，砂堤的供给来源于地表以下1.5 ~ 2m的砂层。在冲绳县的古川城遗址，我们研究了形成种姓石墙的石灰石的剩余磁化。结果表明，石灰石被加热到350摄氏度，这支持了16世纪战争中城堡被烧毁的历史证据。在受火山灾害影响的考古遗址中，了解火山喷发所受的加热影响是有价值的。北海道的Tarumae山是活火山，经常对阿伊努人的考古遗址造成破坏。我们对距离火山口几公里的Tarumae山的浮石坠落和/或火山碎屑流进行了磁场研究，发现火山喷发着陆时的温度相当高。

There are many ancient remains and remnants suffered from the natural disasters. It is important to find the evidence of natural disaster at the archaeological sites, and the collaborative research is planned among natural sciences and archaeology.We studied the sand dyke at the archaeological sites. To date the sand dyke formed at the past earthquake, the archaeomagnetic method was developed. By using the method for the sand dyke at Ishizuka site in Toyama prefecture, we successfully determined the Jogan earthquake in 8th century.The sand dyke found at the Uchiide site near Toyama Bay shows the age of AD 1450 ± 50, however there have not been formerly reported earthquakes at 15th century in Toyama Prefecture. After our study, the ancient document is found which suggests the occurrence of this earthquake near Uchiide site. That is, the magnetic study clears the unknown paleo-erathquake from the archaeological sites. By the ground penetrating radar survey, the supply of sand dyke originated from the sand layer 1.5-2m under the surface plane.At the Gushikawajo castle site in Okinawa prefecture, we studied the remanent magnetization of the limestone forming stone wall of caste. The results indicate that the limestone was heated up to 350 degrees centigrade, which supports the historical evidence that the castle was burnt in a fire at the war in 16th century.At the archaeological ruins affected by volcanic disaster, to know the subjected heating influence by eruptions is valuable. Mt. Tarumae in Hokkaido is the active volcano and frequently caused the damage on the archaeological ruins of Ainu. We conducted the magnetic study on the pumice fall and/or pyloclastic flow of Mt. Tarumae at the area a few km from the crater, and found that the temperature of the eruptions at their landing is fairly high.