Areal strain increased noticeably in the region around the northern boundary of the Izu Peninsula in September to December 2000 when a lot of low-frequency earthquakes occurred beneath Mt. Fuji. In the same time the seismic activity in eastern Yamanashi Prefecture became low. Since increase of the areal strain indicates reduction of the pushing force of the colliding Izu block, the decrease of seismicity in eastern Yamanashi Prefecture is easily understood. Further, because diminution of the tectonic stress beneath Mt. Fuji implies reduction of the confining pressure in the magma reservoir, we think it is probable that degassing took place in the magma to build up high pressure in the focal region near the chamber which caused the remarkable activity of the low-frequency earthquakes. We suggest the noticeable increase of the areal strain in late 2000 might be produced by a mechanical separation of the Izu block from the Philippine Sea plate or detachment of the crust of the Izu block as proposed by Seno (2005).

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The purpose of this research is to understand the placement of scenic views of Mt. Tsukuba, along with specific preservation policies, in the plans and systems of the local governments that lie within the visual range of Mt. Tsukuba, and therefore to consider issues related to the preservation of such scenic views. It has become clear that Mt. Tsukuba is mentioned in the landscape plans and city master plans of the municipalities of an extensive part of the Kanto region. These include Saitama Prefecture, Chiba Prefecture, the city of Tokyo, and other areas. While the statements related to Mt. Tsukuba are of a diverse nature, many of them concern the placement of scenic views and also indicate specific viewpoints. However, in examining specific regulations, it becomes clear that neighboring regional governments have no district-wide policy, and individual regulations are not compliant with the larger plan - the District-wide Plan for the Formation of Scenic Views of Mt. Tsukuba. It is possible for the local governments currently designating Mt. Tsukuba as a scenic view to cooperate in establishing a district-wide program. Such a program would apply beyond a single vicinity and cross municipal areas.

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In order to precisely calibrate the instrumental drift of superconducting gravimeters with absolute gravity measurements, instrumental offsets of the absolute gravimeters used for the measurements must be known to the precision on the order of 0.1 μGal. In this study, absolute gravimeters FG5 #109 and #241 owned by Earthquake Research Institute, The University of Tokyo were compared for precisely calibrating relative offsets of the instruments. Two experiments at Tokyo and Mount Fuji gave consistent results, though the uncertainties in the experiment at Tokyo were large. The experiment at Mount Fuji achieved calibration precision of 0.33 μGal. Frequencies of the Rubidium clocks used with the absolute gravimeters were also measured against the Hydrogen maser clock at Mizusawa VLBI Observatory, National Astronomical Observatory of Japan.

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古墳時代中期の最も特徴的な遺産は,大阪平野の南部に築かれた巨大な前方後円墳である。倭王権の象徴として確立した前方後円墳は,この時期に規模が頂点に達し,前方後円墳を中心とした政治秩序が列島各地で新たな展開を示している。ここでは,古墳時代を出現期・前期・中期・後期・終末期の5期に区分する立場から中期の諸要素に注目し,東国の地域首長墓に投影された中期倭王権の実像の一端を明らかにしたい。
中期の諸要素は,韓半島を通じて受容した新しい技術によるところが多いが,それが定着し普及するには一定の時間を要している。また,すでに前期後葉から存在し中期に発達した要素もある。中期を大きく2段階に分けるならば,前期後葉から受け継いだものと進取の要素で構成される前半と,前期的な要素が払拭され,新たな技術革新が首長墓に集約される後半段階に分けることができる。
ここで取り上げる木更津市高柳銚子塚古墳は,中期前半から後半へ移り変わる時期を代表する東国の前方後円墳のひとつである。古墳時代全般にわたって畿内とのつながりが濃厚な東京湾東岸地域に立地し,波及する倭王権の変化をかなり直接的に受容した地域の首長墓として注目される。現存する墳丘は後円部の一部を残して大きく削平されているが,盾形周溝をもつ140m級の前方後円墳に復原可能である。埋葬施設も破壊され石棺の底石が残るのみであるが,その形式から中期の王陵に用いられた長持ち形石棺の系統をたどることができる。また,墳丘に樹立されていた埴輪が採集されており,2次ヨコハケ調整と突出度の高いタガなどの中期円筒埴輪の特徴を備えている。
一方,木更津「長州塚」出土品と伝えられてきた6点の石製模造品があり,直弧文の陰刻をもつ刀子をはじめ,精巧な造りの製品であることで知られる。これらがこの古墳にともなう可能性が高いことは既に先学によって指摘されているが,改めてその位置づけを検討し,墳形・石棺・埴輪の分析に加えたい。
これらの限られた要素で中期前半の首長墓を検討するため,下総・常陸・毛野・下野・武蔵・遠江の類例を比較している。

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The purpose of this research is to clarify, via document survey, changes in how people might perceive Mt. Tsukuba as a result of making alternative mountain-climbing routes. Mt. Tsukuba has two peaks, Mt. Nantai and Mt. Nyotai. Gods are enshrined on both peaks, and Tsukubasan Shrine is located halfway up the mountain where it serves as a front shrine. Climbing pilgrimages for mountain worship have been popular; over time, however, there has been a gradual transition from mountain pilgrimages to tourism-based mountain climbing. The chief climbing route starts at Tsukubasan Shrine, goes via Mt. Nantai to Mt. Nyotai, and then back to the shrine. This route remains the same for tourist climbers. However, as visitors coming by car have increased since the Showa era, traffic congestion at the mountain base has become a problem. To help ease this, roads were established through Tsutsujigaoka from the mid-1960s on, and many new tourist resources have been created. While this has enabled diverse entertainment options, conversely, tourism resources not appropriate to the original spirit of Mt. Tsukuba have also been constructed. Mt. Tsukuba has a very long history. Needed is multifaceted preservation suited to Mt. Tsukuba, such that its ancient history is neither damaged nor lost.

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本稿は,霞ヶ浦岸の沖積低地における蓮根生産について,栽培導入期の異なる2集落(土浦市田村・沖宿)の土地条件の差異が,蓮根経営にどのような影響を与えているかを明らかにしようとしたものである.
霞ヶ浦岸の中でも土浦入北岸は,全国一の蓮根の集団産地であるが,特に減反政策以後に蓮田面積の増加が著しい.しかし,新たに産地化した栽培地の土地条件をみると,必ずしも蓮根生産に好適とはいえない水田が見受けられる.これらの水田を経営する農家は,蓮根に適した土地条件をそなえた水田を経営する農家と比べ,同程度もしくはそれを上回る生産費を投下しているにもかかわらず,単位面積当たりの収量が低いために,農業所得率・土地生産性・労働生産性において低位であることが明らかとなった。減反政策以後,栽培面積は拡大したものの,所与の土地条件の差が経営内容にも影響を与えているといえよう.この場合,転作奨励金が,結果として,土地条件の差によってもたらされる収益の開きを補完する役割を果たしており,新興産地の経営が転作奨励金に大きく依存している状況をうかがい知ることができる.

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