Northern Tohoku Research Articles

Family resemblances: Memorial images and the face of kinship

In some northern Tohoku institutions, a dedicated hanayomeningyŌ (bride doll), infused with the spirit of the bodhisattva JizŌ, functions as a spirit spouse for the unquiet soul of a child or youth who died before marriage. Although the figurine used is the opposite sex of the deceased, the doll's face is widely believed to come to resemble that of the dead person. These imputed cross-cutting family resemblances (in Wittgenstein's sense) emerge from the enigmatic double life of ritual images, which may simultaneously be experienced as representations of distant beings and as efficacious entities in their own right. By building up an extended web of partial associations among the living, the dead, and memorial images, those who dedicate and pray to hanayomeningyŌ help regulate relations between categorical domains of existence. In facing the dead, the living thus mimetically represent and reproduce generative principles of human kinship.

年平均気温の変動から推定したリンゴおよびウンシュウミカンの栽培環境に対する地球温暖化の影響

This study was undertaken to assess the impact of global warming on the production in Japan of apple (Malus domestica Borkh.) and satsuma mandarin (Citrus unshu Marc.).The annual mean temperature was used to simulate possible changes in favorable regions for the cultivation of apple and satsuma mandarin. The temperature ranges assumed to be appropriate for fruit production were 6-14 °C and 7-13 °C for apples and 15-18 °C for satsuma mandarins, respectively. The database of Climate Change Mesh Data (Japan) was used to calculate annual mean temperatures under the climate change scenario, derived from four Atmosphere-Ocean General Circulation Models (AOGCM) at all 10 × 10 km mesh. It was predicted that the favorable regions to cultivate apples and satsuma mandarins will gradually move northward. In 2060's the plains of central Tohoku will be unfavorable for apple cultivation, while most of Hokkaido will be suitable. The plains of northern Tohoku are predicted to attain the annual mean temperatures higher than those of the current main producing districts. By 2060's, the favorable areas for satsuma mandarin production will possibly move from the southern coastal sites to inland areas of western and southern Japan, the plains of Kanto and the littoral zones of the Japan Sea in the central and western Japan and in southern Tohoku. Therefore, global warming will greatly affect the cultivation environment of apples and satsuma mandarins in Japan by the middle of the 21st century.

The Emishi society and the trade system in the northern Tohoku district

The Emishi society and the trade system in the northern Tohoku district

物理定数から見た白亜紀－古第三紀花崗岩類－ その1．東北地方北部

本研究は, 日本列島に分布する白亜紀－古第三紀花崗岩類を対象に，それらが持つ物理定数，密度・孔隙率・磁化率・残留磁化そしてQn比（Königsberger ratio）などを系統的に集約し，花崗岩類が共通して持つ性質や，それとは逆に，各時代や地域が持つ特有の性質を明確にし，地質構造の解析や，公害や環境問題，災害予知など各方面に必要な基礎資料を提供する事を目標にとりまとめた．今回は東北地方北部を対象に570余露頭より採取した花崗岩試料の結果を集約した. 対象とした４地域は，北上山地，太平山地域，栗駒－鳴子地域そして村上地域である．その結果は以下のようである． 4地域の平均密度は2.66～2.77（ｘ１０３ｋｇ/m 3）で村上地域が一番小さく北上山地が最も大きい. 孔隙率は0.4～0.6 ）で地域による差は殆んど認められない．磁化率は密度が2.60～2.95の変化（SiO2は約77～42（％））に対し10倍に増加する．これらの関係において磁化率はまた，上限,下限の2直線に挟まれる範囲に収まり, 4地域独自の空間を占有する．Qn比は0～0.4を示すものが圧倒的に多く, 磁気図解釈の際，残留磁化を考慮する必要はない．磁化率の低い岩石にも残留磁化を担う強磁性鉱物が存在している．

Distribution of Soybean dwarf virus Strains in Northern Tohoku Region in 2002

Distribution of <I>Soybean dwarf virus</I> Strains in Northern Tohoku Region in 2002

Phylogeography of a freshwater sculpin, Cottus nozawae , from the northeastern part of Honshu Island, Japan

The fluvial sculpin, Cottusnozawae, is a coldwater-adapted fish distributed in Hokkaido Island and the northeastern part of Honshu Island (Tohoku District), Japan. Mitochondrial DNA (mtDNA) control region sequencing was used to investigate the geographic distribution of genetic variation and phylogeography of C. nozawae. Most populations possessed unique haplotypes, few being shared across river systems. Phylogenetic analysis of the sequences of the mtDNA control region and adjacent regions of C. nozawae revealed three distinct phylogenetic groups that differed by 3.05% to 3.11%, corresponding to distinct geographic regions, Hokkaido Island, northern Tohoku District, and Yamagata Prefecture (southwestern Tohoku District), respectively. The divergence times of three groups were estimated to be about 1.5 million years ago by applying a general rate for mtDNA, suggesting that the divergence among them might have occurred in the early Pleistocene. Divergence among the haplotypes within the group from the northern Tohoku District was also high (1.84%), no haplotypes being shared by local populations in different river systems in this region. Local populations from a single river system in this region comprise a distinct lineage that differed from other river systems. Such genetically divergent population structures among the different regions and river systems are considered to have resulted mainly from long-term isolation and restricted gene flow among river systems, probably promoted by the fluvial benthic life history and low dispersal ability of this species.

Tectonic stress state in NE Japan as part of the Okhotsk plate

An existing geodetic flow velocity model, obtained by using an internal free network adjustment technique, is used to derive estimates for various strain rates parameters in NE Japan. The greatest shortening rates of the principal strains, trending ∼E–W, are located in regions where much steady, internal, frame-invariant plastic flow deformation is observed to be taking place. The internal geodetic adjustment technique yielded the internal deformation in the Tohoku arc; most of the intraplate deformations, including the much folding deformations observed in the inner zone, are produced from within. An interseismic transient elastic loading at a strongly coupled/locked Japan trench would not be needed. The observed ongoing extensive ductile folding deformation in the inner zone of Tohoku may mean that the geodetic strain rates, causing shortening at ∼2–3 cm/yr, probably reflect the more correct level of the deformation, which is steady/permanent, in NE Japan as compared with seismic/faulting data, which indicate ∼0.5 cm/yr shortening. The calculated principal strain rates are used to make an interpretation for the origin of the deviatoric principal stresses within the greater regional plate tectonic framework. The tectonic stress state in NE Japan, as part of the Okhotsk plate, could mostly be influenced by the Okhotsk plate, which is extruding southward to lessen the significant accumulated contractional deformation in NE Asia in the Verkhoyansk–Cherskii mountains. The principal strain rates are ∼N–S extensional essentially everywhere in NE Japan, as a result of the southerly extrusion, except in its southernmost leading edge, in the Uetsu/Fossa Magna province, where the Japan Alps rampart rises in front of the extrusion. Here an ∼E–W compressional stress state prevails. A second ∼E–W contractional zone is found in north-central Tohoku, extending from the Sanriku province in the outer zone to the inner zone in the Japan Sea side, being more prevalent in the latter zone. The calculated rotation rates from the geodetic flow model are clockwise (CW) in both of the ∼E–W contractional regions. NE Japan, extruding southward, faces buttresses in (1) the Oga–Ojika Line (OOL), and/or a crustal weakness zone between the northern and the southern halves of Tohoku approx. at ∼38.5°N latitude, and, especially, (2) the Japanese Alps rampart; these obstacles cause the northern and southernmost Tohoku to veer to its right and rotate CW, thereby setting up the ∼E–W-trending compressional deformation in their respective inner zones. Between the OOL (or the 38.5°N boundary) and the Kanto Tectonic Line (KTL), the sense of the differential rotations is counterclockwise (CCW), towards the ocean to the SE. The northern Tohoku (north of the OOL) and the southernmost Tohoku (south of the KTL) cannot rotate CCW towards the ocean because of the Izu block's collision in the south and the relatively strong coupling along the subduction interface beneath the Japan trench in the north off-Sanriku. The relatively stronger long-term coupling between the northern Tohoku and the Pacific plate at the Sanriku coast, with respect to that in off-Fukushima, is due to a flatter subduction of the Pacific slab there, increasing the plates’ interface contact area; the flattening of the subduction dip angle was caused by CCW rotation and shifting of the northern Tohoku along the dextral Honjo–Matsushima Line, roughly corresponding to the OOL, towards the Pacific and overriding of the subduction zone during the formation of the Japan Sea.

長大飼料作物収穫・麦類施肥播種同時作業機による飼料作物１年２作体系のシミュレーションと実証

1. A prototype combined seeder comprised of a forage harvester, a rotary tiller, a fertilizer and a seeder for dentcorn·sorghum-barley·rye double cropping systems was developed. The working hour of combined seeder for dentcorn harvesting and rye seeding work in test field (30a) was 12.2a/h.2. Using the combined seeder, dentcorn-rye cropping system and sorghum-barley cropping system showed maximum average yields of 2.7t/10a (DM). The forage crops were improved in qualities as silage materials because of longer culture periods by the combined seeder.3. The simulation results of 11 years (1985-1995) using precipitation data of Morioka in field area of 5ha show that the combined seeder with the work efficiency 12a/h completed 5ha of dentcorn·sorghum-rye·barley cropping systems same as forage-harvester with the work efficiency of 24a/h did. And the combined seeder will finish rye or barley seeding work earlier than individual harvesting and seeding works do. The combined seeder shows merits of efficient works and better forage crop qualities in northern Tohoku Area.

地形改変を伴う開発地域周辺の風向・風速変化予測

It was considered that land deformation influenced on the wind shift around the development area. Statistical study was conducted on the influence of topography upon the wind directions and the wind velocity at the 60 meteorological stations (AMeDAS weather stations) in the northern Tohoku district. It was recognized that the wind were affected by the surrounding topography. It was obtained the quantitative equation (1) between the frequencies of the wind directions (F) and the deviations of inclination of the same directions (K). Fsp = -22.8 K + 5.44 (in spring) ········· (1) Equation (2) shows the relationship between the mean wind velocity and the variables K. Vsp = -3.11 K + 1.98 (in spring) ········· (2) It became possible to predict the change of the wind system around development area by the use of these equation. The case study was carried out at the quarry. As a result, it was predicted that the wind system around the quarry would change. It was considered that cutting down trees had influence on wind velocity around the development area. Wind velocity around the development area was predicted by using effect on the windbreak forest. It was predicted that there were points where wind velocity became slow by cutting down trees at the leeward side after the development. There were points where the wind velocity fast because the effect of protection against wind was lower due to the fall of leaves.

Density suppression of Plutella xylostella (Lepidoptera: Yponomeutidae) by multiple releases of Diadegma semiclausum (Hymenoptera: Ichneumonidae) in cabbage fields in Iwate, northern Japan.

The exotic parasitoid, Diadegma semiclausum, was introduced and augmented to suppress the density of the diamondback moth, Plutella xylostella in cabbage fields at two localities in Iwate Prefecture, northern Japan, from 1996 to 1999. The parasitoids were released at densities of 0.8-3.4 copulated females per plant. In 1996, the numbers of both fourth-instars and pupae of P.xylostella in the field where parasitoids were released remained below five individuals per plant from release until harvest in late July. This was much less than the levels in the control field, where the peak density was 17.8 larvae and 11.2 pupae per plant. Percentage parasitism by D. semiclausum reached 53% in the release field in mid June. Successful overwintering of D. semiclausum in the northern Tohoku district of Japan was observed in the survey conducted from June to July of 1997. However, the percentage parasitism was reduced to a maximum of 29% in 1997 when no additional parasitoids were released. The release of the parasitoid was repeated in Nishine in 1997 and in Morioka in 1998 and 1999, resulting in successful suppression of P. xylostella.

Yearly Change of Frequency and Geographical Distribution of A2 Mating Type Isolates of Phytophthora infestans in Japan from 1987 to 1993.

Isolates of Phytophthora infestans were collected from potato and tomato in Japan from 1987 to 1993, and their mating type (A1 or A2) was determined. In 772 isolates collected from potato during 1987 to 1993 in Hokkaido, the frequency of A2 mating type strains increased from 54% in 1987 to 97% in 1993. In eastern Hokkaido A2 strains were already present at a high frequency in 1987 and 1988, and since 1989, A1 strains have not been detected. In western Hokkaido the A1 strains were common in 1987 but decreased in frequency after 1990. The geographical distribution of the A2 strains seems to have spread westwards in Hokkaido. Of 539 isolates collected from potato during 1988 to 1990 outside Hokkaido, the frequencies of A2 mating type isolates were 72%, 96%, and 87% in 1988, 1989, and 1990, respectively. The A2 strains were already highly predominant in western Japan in 1988, while the A1 strains were common in Kanto and Tohoku districts, the eastern part of Honshu. However the frequency of A1 strains decreased even in Kanto and Tohoku districts in 1989 and 1990. The geographical distribution of the A2 strains seems to have spread northeastwards outside Hokkaido. There were some fields where A1 and A2 isolates were found together in western Hokkaido and northern Tohoku in 1990, but after 1990 such fields became very rare in Hokkaido. The high predominance of the A2 strains suggests that the probability of oospore production by mating is low in Japan. Seven out of eleven tomato isolates collected were of A1 mating type and four were of A2, indicating a significantly higher proportion of the A1 strains from tomato than from potato.

東北地方北部及び北海道南部の3次元&lt;I&gt;P&lt;/I&gt;波減衰構造

東北地方北部及び北海道南部の3次元&lt;I&gt;P&lt;/I&gt;波減衰構造

積雪寒冷地における室内環境問題の過去・現在・未来 北東北における結露問題

積雪寒冷地における室内環境問題の過去・現在・未来 北東北における結露問題

Tomographic inversion for P wave velocity structure beneath the northeastern Japan arc using local and teleseismic data

We have determined three‐dimensional P wave velocity structure up to a depth of 296 km beneath northern Tohoku, Honshu, Japan, by inverting arrival times of local and teleseismic events simultaneously. Velocities in the upper crustal layers correlate well with the surface geology and Bouguer gravity anomalies. Low‐velocity zones are ubiquitous in the crust and the uppermost mantle beneath the Quarternary volcanic areas. A well‐known feature of a pronounced low‐velocity mantle wedge underlain by the dipping high‐velocity (high‐V) Pacific plate is generally recovered over the study area. Strong heterogeneity within the high‐velocity Pacific plate is suggested by the presence of a pronounced low‐velocity anomaly confined to the depths of 130–200 km. The decreased seismicity of intermediate‐focus events may be correlated with the low‐velocity zone. A two‐dimensional inversion scheme was invoked to determine stably the average mantle structure perpendicular to the island arc. In the depths of 50–150 km, the inclined high‐V zone has a thickness of 80–100 km with its top coinciding with the upper plane of the double‐planed deep seismic zone. Below the depth of 200 km, the high‐V zone is shifted toward the bottom of the 80‐km‐thick reference slab. In the intermediate‐depth layer (150–200 km), the high‐V zone is not clearly visible within the 80‐km‐thick reference slab.

Multifractal and entropic properties of landslides in Japan

Landslide distributions in two major areas of northern Japan, Tohoku and Hokkaido, are analysed for multifractal properties. For the latter data set, also the multifractal spectrum for the spatial landslide size distribution is determined and compared to the probability distribution. It is concluded that the fields possess definite multifractal character. This finding is supported by the known multifractality of the main triggering processes, rain and earthquakes. Further support comes from a configuration entropy analysis which is found to be a useful complimentary tool to multifractal analysis. Models leading to multifractality are briefly reviewed. Careful attention is paid to the algorithms used and to the verification of the numerical results. Some general suggestions concerning numerical methods are made.

仙台市における宿泊機能の立地特性

The objective of this study is to examine the centrality of Sendai City in the regional urban system in the Tohoku district through the analysis of agglomeration processes and locational patterns of lodging facilities and their operations in urban areas. Japanese lodging facilities can be divided into two main categories : Japanese style lodging, called ryokans, and western style hotels.Most lodging facilities in the Tohoku district were composed of ryokans in the 1960s. When the size and number of hotels began to increase rapidly in Sendai in the early 1970s, western style hotels multiplied in the Tohoku district, following the trend that occurred in the main metropolitan regions of Tokyo-Yokohama and Kyoto-Osaka-Kobe. The increase in the number of hotels in Sendai, as well as in Sapporo, Hiroshima and Fukuoka in this period, signifies that hotel construction diffused from the largest cities to regional central cities following the national urban hierarchy.After the first increase in hotels in Sendai, hotel construction diffused to prefectural capitals and other major cities in the Tohoku district. This agglomeration process reflected the spatio-temporal differences among the cities. Each city is different in terms of population size and growth, urban functions and access to major transportation networks. In Morioka City, for example, the number of hotels increased rapidly in the early 1980s, after the opening of the Tohoku-Shinkansen (Tokyo-Morioka), which connected the northern Tohoku district with Sendai or Tokyo. The opening of the Tohoku-Shinkansen also resulted in the second rapid hotel increase in Sendai.While the number of ryokans in urban areas has remained stable or has decreased since the 1970s in the Tohoku district, locational patterns of ryokans and hotels have changed considerably, especially in Sendai. In 1970, the majority of hotels were ryokans, which were densely located, traditionally in the CBD and its surrounding areas in Sendai. However, after the first and second phase of new hotel construction, ryokans located in the CBD decreased rapidly because of rising land prices and the construction of high-rise buildings. As a result, in 1996 the western style hotels were clustered in the CBD, while ryokans remained dispersedly in the surrounding CBD areas. However, few hotels were located in the core of Sendai's CBD near the station because this area had already been developed before the first increase in the number of hotels.The rapid and large-scale increase in the number of hotels in Sendai was a result of an increase in the range of services that they provided. Most of the hotels constructed during the first period of increase were commercial hotels catering to the needs of tourists. Therefore, the main function of their hotels was lodging. However, many hotels that were built during the second period of increase were equipped with convention facilities. Thus, hotel operations started to revolve around banquets, conventions and restaurant dining. These operations, especially large-scale convention halls, also attracted business customers from Tokyo and the Tohoku district.The agglomeration processes of lodging facilities reflect the regional urban system and urban structure, and the functions of lodging facilities signify the geographical characteristics and the centrality of Sendai.

An Interpretation of Magnetovariational Data in the Northern Tohoku District, Japan, Using Multi Sheet Modelling.

Magnetovariational data from thirty-seven sites in the northern Tohoku district of Japan are modeled quantitatively using a multi thin-sheet modelling program. The primary objective was to determine if current channeling of electromagnetic fields through the Tsugaru strait, to the north of the survey region, can account for the behavior of the observed large real induction vectors. The major conclusions that we draw are: (1) northward-directed induction vectors at 256 s period cannot be fully explained only by the channeling effect through the Tsugaru strait especially in the area to the east of the Quaternary volcanic front, and (2) a conductive anomaly is necessary at a depth of 10 km in the forearc region in order to account for the induction vectors at 16 s period.

西南北海道‐東北地方北部に広がる後期更新世の広域風成塵堆積物

西南北海道‐東北地方北部に広がる後期更新世の広域風成塵堆積物

The Status of Black Woodpecker in Northern Tohoku District, Japan.

The Status of Black Woodpecker in Northern Tohoku District, Japan.

The long-range eolian deposits formed during the late Pleistocene in south-western Hokkaido to northern Tohoku region in Japan and their origin

The long-range eolian deposits formed during the late Pleistocene in south-western Hokkaido to northern Tohoku region in Japan and their origin