Mountains have been worshiped in Japan since ancient times. Similar to Mt. Fuji, Mt. Ontake has been a site of worship ascents since the Edo era. We previously examined the style of mountain huts on Mt. Fuji during the Edo era, and in the present study, we have expanded our scope to Mt. Ontake. We conducted field surveys on the Kurosawa and Otaki trails on Mt. Ontake and found a common architectural characteristic, the so-called “central path style” floor plan (or “Nakadori style”), in which the trail passes through the mountain huts. A previous study reported that this floor plan is similar to that of somagoya (loggers’ huts) in this area. Therefore, we examined historical materials and investigated the establishment and transformation of this “central path style” floor plan and the relationship between mountain huts for worship ascents and forestry.

 Many mountain maps drawn in the Edo or Meiji era have legends showing mountain huts on as opposed to beside trails, suggesting that the “central path style” floor plan might date back to the late Edo era. Mountain huts were first donated as guardian huts around holy places, places for religious training, and shelters against the harsh mountain environment. They were then expanded to serve as teahouses or lodgings. In addition, many of the mountain huts on the Otaki trail had the “central path style” floor plan since the Meiji era. Since the Edo era, residents of Kurosawa and especially Otaki village in Kiso valley earned their living by felling trees. The loggers’ huts in Kiso had a “central path style” floor plan and was called “Nakagoya”. Both trails had a mountain hut for worship ascents called “Nakagoya.” It seems that the “central path style” floor plan we discovered on field surveys was inherited from somagoya, based on the livelihood of the residents.

 On the other hand, we found another, lost architectural characteristic from old documents called the “double hut style” floor plan (or “Ryogoya style”). At Tanohara on the Otaki trail, two huts were found opposite each other on the trail from the Edo to the Meiji era. However, by the Taisho era, the space between the huts was covered and changed into an interior, i.e., the “central path style” floor plan. We found a similar religious building with a “double hut style” floor plan on the Yoshida trail on Mt. Fuji. Since the Edo era, both the Tanohara Ryogoya on Mt. Ontake and the haiden (front shrine) of Fuji Omuro Sengen Jinja on Mt. Fuji were used as komorido, where ascenders, especially women, would chant, practice abstinence, and sleep. Thus, it seems that the “double hut style” floor plan was universally established for mountain worship.

 Mt. Ontake is an object of worship for believers and provides a living for local villagers. The mountain huts that have supported worship ascents since the Edo era have architectural characteristics related to mountain worship and livelihoods. Both the “Ryogoya” and “Nakadori” styles have a strong connection with huts and trails, and this is a special characteristic of the mountain huts on Mt. Ontake.

 After the volcanic eruption of Mt. Ontake in 2014, some mountain huts on Kurosawa and Otaki trails were closed, demolished or reconstructed. We hope the results of our research help preserve traditions of the mountain huts on Mt. Ontake.

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On 14 th September in 1984, the NAGANO-KEN-SEIBU Earthquake causued the people in Ohtaki-mura to incur a great loss of life and property. This research paper aims mainly at giving a general outline of the recovery process of people's livelihood in the above condition, in the method of questionnaire that sent to all the house-holders in Ohtaki-mura as the most strongly stricken area. The conclusion is summarized as follows : (1) Economic loss of whole properties averages 3.12 million yen a househould. This value of loss corresponds to 53 % of one household's annual income on the average. (2) After the earthquake, many people were afraid of aftershocks and were very inconvenient for the destruction of water supply, damage of each house and interruption of traffic service. (3) The recovery process of people's livelihood can be shown as the curve of restoration concerning 13 factors of living ! bathing, cooking, washing, shopping and so on. The recovery process can be distinguished as the five stages according to the period of 70 % accumulation for each restoration. (4) Recovery of each steady livelihood is related to the start of repairs for dwellings.

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昭和59年（1984年）9月14日，長野県と岐阜県にまたがる御嶽山一帯を襲った「長野県西部地震」では大小さまざまな山腹崩壊地が発生した。その被害は，木曽郡

を中心に長野県西部14町村に及び，各所で発生した土石流や地すべりにより死者・行方不明者29名を出す大惨事となった。なかでも御嶽山南西斜面に発生した大崩壊地（通称：御岳崩れ）は，濁川，伝上川流域の国有林を中心に大きな被害をもたらした。長野営林局（現中部森林管理局）では「災害対策本部」を即日設置し復旧事業を開始した。この復旧事業は昭和59年から平成21年（2009年）まで治山ダム，護岸工等を施工し，総額約137億円が投じられた。それから30年後の平成26年（2014年）9月27日に，死者58名，行方不明者5名の戦後最悪といわれる御嶽山噴火災害が発生した。この噴火により発生した土石流を長野県西部地震の復旧対策で設置した治山ダム群が減勢するとともに，下流域への土石流の流下を軽減した。中部森林管理局，木曽森林管理署では噴火直後から関係機関等と連携を図り，二次災害の防止，監視体制の強化，地元説明等を行った。恒久的な減災対策工として，木曽町三岳倉本湯川流域にコンクリート谷止工1基を完成させるとともに，濁川流域にコンクリート谷止工2基を施工中であり早期完成を目指している。

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To investigate the water qualities of natural waters in Ohtaki Village, where there was a large-scale landslide caused by the Western Nagano Prefecture Earthquake in 1984, water samples on river streams were taken in 1992.(1) Water qualities are classified into three types, Ca-(HCO₃) ₂, Ca-SO₄ and Na-HCO₃ as likely results by YOSIOKA et al. and OKUDA et al. .(2) Water qualities are shown two principal components PCl which shows degree of weathering and PC2 which shows Ca-(HCO₃) ₂ type or Ca-SO₄ type.(3) Water quality values of PC1 and PC2 on Denjo-river were small before the earthquake, and larger after it and gradually tend to decrease.

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　御嶽山の火山災害と王滝川のpH変動の歴史を記録文書から検証する。御嶽山はこの半世紀，二度の噴火や地震による地滑りを引き起こした。災害は，河川の水質や水棲生物，また地域社会に影響を与えたことであろうが，災害と環境変化との因果関係が十分に解析されてきたとは言い難い。
　御嶽山に発する濁川が噴火直後の降灰によりpHを下げたとの証拠は，過去の観測記録では確認されない。pH低下は硫酸を含む湧水の量や硫酸濃度が火山の活発化により増加したことによる。
　1984年の地滑りは濁川・伝上川合流点附近を埋めた。濁川下流では硫酸濃度が増加したがpHは上昇した。一次生産者の活性の増大や，災害復旧工事に大量のコンクリートが使用された結果として中性化の機構が働いたためであろう。
　濁川が流れ込む牧尾貯水池では噴火後にpHが低下した。低下は降灰の効果ではなく，湖底に堆積した火山噴出物中の硫化鉄が微生物により酸化されて硫酸を産生したためである。噴出物が大規模な降水の際に貯水池に流れ込むため，低pHが長期化したのであろう。
　二度にわたる噴火が御嶽山麓の

に経済的な被害を与えることはなく，噴火後の人口流出も顕著ではなかった。1950年代からの人口減少は村域の生産的な部分を湖底に沈めた牧尾ダムの建設による。の衰微はダムが造られた河川に共通に見られる事例であり，火山災害が主因ではない。

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日本では1980～90年代にかけて，林内，林道，里道，登山道等を「野外トレイル」として走行するマウンテンバイカーが増加してきた。しかしその過程では，森林所有者や他の利用（ハイキング・林産物採取等）との軋轢が増し，林内の走行を規制されるケースも目立ってきた。このため，2000年代以降，「野外での走行を継続的に楽しむには，周囲の理解が不可欠」というバイカー側の危機意識を主に反映して，特定の地域に密着しつつマウンテンバイク用のトレイルを確保する動きが生まれている。本稿で扱うB.C. Porter，西多摩マウンテンバイク友の会，Trail Cutter，西伊豆古道再生プロジェクト・山伏トレイルツアー，の事業においては，このトレイルの確保にあたって，レジャー施設への併設，地元集落・森林所有者との合意形成，地方自治体との連携が積極的に進められ，バイカーを組織して自治体・集落レベルの森林整備に積極的に協力する事例もみられる。この動きは，森林の荒廃や過疎化に悩む山村にあって，自治体・集落や所有者にも受け入れられつつあり，他の利用者との競合を回避した森林の有効利用の可能性をも提示している。

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本研究では,国有林野における森林レク事業の国有林ならびに地域社会にとっての今日的意義および問題点を明らかにすることを目的として,長野県木曽谷地区を事例に,中でも典型的な利用形態である「スキー場型」国有林野利用を地元主導で進めてきたの取組みについて分析を行った。その結果,おんたけスキー場は1990年代初頭までは民宿等の発展や雇用創出など地域への経済的波及効果の面で多大な成果を上げてきた。しかし,現在ではスキー人口の頭打ちやスキー場乱立の影響で利用者は激減し,木曽谷地区でも大問題となっている。こうした状況については,1980年代後半からの国策的な民活型大規模リゾート開発の推進および自己収入確保の観点から積極的にこれに乗じてスキー場等の開発を進めた国有林の施策展開にも大きな責任がある。村は新たな展開として国有林内林道を活用したイベント等,より多面的な利用に期待している。こうした動向が,従来よりも国有林と地元との関係をむしろ強める方向に働いていることから,多面的な森林レク事業的国有林野利用は地域社会と国有林との現代的な関係の再構築という意味で今日的意義を持ち得ると言える。

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The geomagnetic total force survey using a proton magnetometer was carried out around the epicenter of the 1984 Western Nagano Prefecture Earthquake (1984. 9. 14, M 6.8) in December 1984 and December 1985. Geomagnetic anomalies ranging from -200 to -500 nanoteslas were observed along the southern boudary of the aftershock region. It is considered that these negative anomalies reflect the crustal structure around the earthquake fault extending to N70°E direction. Obseved anomalies reveal that there is the vertical contact separatig layers of differig magetic susceptibilities at the depth deeper than several ten meters. The magnetic susceptibility of the layer lying south of the contact is 0.002 to 0.005 lager than that of the layer lying north. The vertical contact is 100 to 200 meters thick.
Changes of a few nanoteslas were observed during the period from December 1984 to December 1985. However, further study is necessary to conclude whether these changes were associated with the earthquake because the accuracy of diurnal correction was still not satisfactory.

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Recently, the seismic activity of the earthquake swarm southeast of Mt. Ontake has been studied by many researchers, especially after the volcanic eruption on October 28, 1979 because of the proximity of both events in time and space. This paper deals with the focal mechanism solutions with the aid of temporary stations installed after the eruption.
Directions of the P-axes are separated into two groups. One is in N70°W-N80°W directions though T-axes are distributed in girdle (Strike-slip, oblique-slip and dip-slip types are equally observed in the earthquake swarm). Directions of N70°W-N80°W are coincident with the pressure direction in the inland of Chubu District, central Honshu and they are supposed to be the pressure directions of the tectonic stresses in this focal region.
The other group is in N40°W direction, which is apparently inconsistent with the tectonic stresses. Earthquakes belonging to this group are strike-slip types and are occurring in the two limited regions. One is in the east of Mt. Ontake and the other is in the vicinity of Kuzoo (central part of this focal region) and is aligned across the earthquake swarm region. Such an activity indicates the existence of an active fault inconsistent with the present tectonic stresses.
It becomes clear from the present study of focal mechanisms that small amplitudes of S-waves observed at Maze (to the west of Mt. Ontake) are not accounted for the attenuation of S-waves but for the focal mechanisms of the earthquake swarm.

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