The Nakayama wind-hole in Shimogo, Fukushima, is a famous natural monument where cold air vents from the foot of the tales along the mountain during summer. The wind-hole with various species of alpine plants is a wellknown tourist attraction, but has been decaying in recent years. The local government has replanted the surrounding forest to protect the natural monument. However, protection efforts might result in further destruction if we do not understand the mechanism of the wind-hole well. The first step in protecting the important natural monument is thus to understand the mechanism of the cold air vent at the Nakayama wind-hole.
In this study, we carried out extensive in situ observations of the wind-hole in both summer and winter in 2001. In summer, cold air blows from the cold wind-holes at the foot of the talus. It has been inferred that the air inhaled at the warm wind-hole up the slope cools in the tales and blows out from the cold wind-hole. To confirm this speculation, we conducted a tracer experiment using CO₂, which is harmless to the environment. As a result, it was found that the air inhaled at the warm wind-hole is exhaled from the cold wind-hole 140 m downslope only after 90 minutes. Based on the resulting mass flux of 2.6cm/s and the known cooling rate of the air, we found that a total of 4×10¹²J of thermal energy is stored in the tales during summer.In winter, on the other hand, warm moist air blows from the warm wind-holes at the top of the tales. Using thermographic instruments, we found that such warm wind-holes are located ubiquitously at high altitudes, especially around Sekichu-no-oka. We measured the surface heat budget at the warm wind-hole and found that 150W/m² of heat flux arises from the underground section of the talus. The heat flux is multiplied by the total area of the warm wind-holes, and a total of 5×10¹²J of thermal energy is released from the talus during winter. The result is consistent, at least in terms of the order, with the amount of heat accumulated during summer.
Hence, we conclude that the cold air gently blowing from the cold wind-hole during summer can be quantitatively explained by the cold accumulated during winter. Convective overturning under the unstable stratification in winter and stable stratification in summer behaves as an effective thermal filter which accumulates only cold in the tales. This mechanism of a natural thermal filter is essential to maintain the cold air vent from the wind-hole during summer. Based on this conclusion regarding the mechanism of the wind-hole, we suggest cutting trees and opening vents around the warm wind-holes after identifying them thermographically to protect the important natural monument of the Nakayama wind-hole.

View full abstract

It is known that a few influential Ainu, who were accompanied by subordinate persons, hunted and traded freely in the eastern part of Hokkaido, northern Japan. Then, around the 1850s under the influence of policy by the Wajin-Japanese, these influential persons nearly disappeared. Furthermore, it is also known that the name-giving prohibition as an element of Ainu culture was applied widely, not only among individual settlement dwellers, but among the inhabitants of each district in the 1850s. The name-giving prohibition among the Ainu dictated that the name of a living neighbor or a dead person should not be given to another individual. However, neither the social structure nor the name-giving prohibition among the Ainu in the early 1800s has been clearly documented previously.
The purpose of this study was to reconstruct the social structure of Ainu society in the early 1800s and to investigate the spatial range of the application of the name-giving prohibition. The findings of the analysis are as follows:
1) The study area consisted of five districts: Etorohu in 1800, Akkeshi in 1803, Shizunai in 1812, Takashima in 1822, and southeast Sakhalin in 1828. The average number of persons who lived in the same household were within the range of 3.4 persons in the Etorohu district to 7.2 persons in southeast Sakhalin (mean 5.0 persons). Household members were classified into two types: core members and lodgers. The core members of the household consisted of the household head, his or her spouse, and his or her son and/or daughter in many cases. The lodgers of the household consisted of persons who lodged in from other households. The average number of settlement dwellers was within the range of 26.2 persons in southeast Sakhalin to 51.2 persons in Akkeshi (mean 33.5 persons per settlement).
2) A total of 1, 386 persons were recognized to be socially subordinate to masters of those, 94.0% (1, 303/1, 386) of the subordinate persons lodged in the same household with their masters. The presence of lodgers in other households was found in all five districts. Of the total number of households in all five districts, 35.4% (333/941) included at least one lodger from a different household. Especially in southeast Sakhalin, 79.2% (228/288) of the total number of households included at least one lodger. In the case of households including at least one lodger, the number of lodgers per household was within the range of one to 14 persons. The average number of lodgers per household was 4.5 persons. Those four or five persons probably had come to lodge in the same household from many different households, because they were not close relatives. Therefore the ratio of lodgers (the number of lodgers from different households total number of inhabitants) was 48.8% (1, 019/2, 089) in southeast Sakhalin. This subordination to others and/or the custom of housing lodgers in other households was recognized as one of the features of the social structure of the Ainu in the early 1800s.
3) In the five districts, no one had the same name as that of a living member within the same household. This was true even in the case of households including nonrelatives as lodgers. The ratio of persons who contravened the prohibition against taking the name of a living neighbor within the same settlement (the number of persons whose names were the same as those of living persons in the same settlement total number of inhabitants) was within the range of 0% to 0.09% by district. When the study area is expanded from settlement to district, the ratio of persons who contravened the name-giving prohibition was within the range of 0.3% to 1.6%. The name-giving prohibition was widely applied, not only among individual household members and settlement dwellers, but also among the inhabitants of each district.
4) The five districts studied were located very far from each other. Furthermore, there was difference of three to 28 years among the data colected.

View full abstract

Fluvial terraces along the lower reaches of the Kamiichi River to the Hayatsuki River, eastern margin of the Toyama Plain, are widely distributed. These terraces are divided into three levels, the Tohfukujino terrace, Nakano terrace, and Oosakino terrace, in descending order of elevation. In the Kamiichi and Hayatsuki river areas, the age of the terraces has not reported, as volcanic ash is not visible within terrace deposits and overlying loamy soil, and there are few outcrops in this area.
In this study, we carried out a drilling survey on the terrace to obtain overlying loamy soil. We extracted some well-known widespread volcanic ash within the loamy soil collected in the drilling samples and estimated the approximate age of the terraces. Below are the main results obtained in this study.
1) The Tohfukujino terrace and Nakano terrace are overlain by the Aira-Tanzawa tephra (22-25 ka), Daisen-Kurayoshi tephra (43-55 ka), and Kikai-Tozurahara tephra (75-95 ka). From the tephrochronology and the sedimentary facies of terrace deposits, we estimate that the Tohfukujino terrace was formed at oxygen isotope stage 6, and the Nakano terrace was formed at oxygen isotope stage 5-d.
2) The Oosakino terrace is overlain by the Aira-Tanzawa tephra and Daisen-Kurayoshi tephra. The Daisen-Kurayoshi tephra contains the lowest part of loamy soil overlying the terrace. We estimate that the Oosakino terrace was formed at oxygen isotope stage 4 or at the stage 4-3 boundary.
3) On the basis of the approximate age of terraces and vertical displacement of active faults, we estimated the average vertical slip rates for the Uozu fault at 0.4-0.5mm/yr (Tohfukujino terrace), ca. 0.4mm/yr (Nakano terrace), ca. 0.4mm/yr (northern part of Oosakino terrace), and ca. 0.2mm/yr (southern part of Oosakino terrace), respectively.

View full abstract