地学雑誌
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123 巻 , 1 号
選択された号の論文の14件中1~14を表示しています
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論説
  • 杉本 興運, 菊地 俊夫
    123 巻 (2014) 1 号 p. 1-24
    公開日: 2014/03/07
    ジャーナル フリー
     In recent years, the impact of tourism on socioeconomic structures has attracted the attention of the Japanese government. To plan and implement effective tourism policies and strategies, it is important to understand the basic characteristics of tourism resources in a given region. Tourism resources have been regarded as one of the most important indices for evaluating the tourism potential of a region and analyzing tourism phenomena. However, previous studies on tourism regions in Japan were based on limited resources and analyses have been largely qualitative. Therefore, this study focuses on a statistical analysis of substantial data, such as the distribution of tourism resources, to clarify the regional characteristics of tourism resources in Japan.
     First, the number of tourism resources, which are assigned a weighted value on the basis of an evaluation ranking determined by the Japan Travel Bureau Foundation, is calculated for each prefecture. The results of the statistical dispersion show that, among prefectures, there are great differences in the quantities of each type of tourism resource. Next, the prefectures are classified into four regional clusters based on similarities of location quotients. The first cluster is abundant in natural landforms and is mainly located in eastern Japan. The second cluster predominantly consists of elements concerning surface water such as lake water and river water and is composed of prefectures at various locations around the country. The third cluster, composed of prefectures in the metropolitan areas of both eastern and western Japan, has extensive urban cultural resources. The fourth cluster primarily contains important natural and cultural components, which are closely located along the Seto Inland Sea and in south-west Japan, including Okinawa. Finally, to analyze the regional attractiveness of each prefecture, the coefficient of specialization and the weighted number of the resources are compared to ranking data on tourist arrivals and projected destinations of domestic tours. The results show that popular tourist destinations have high values in the dimension of the number of tourism resources, and these regions are divided into two types with high or low specialization.
     In conclusion, the distribution of tourism resources determines the characteristics of each prefecture as a tourism region and makes a difference in the regional attractiveness of prefectures. The comprehensive analysis of a wide variety of tourism resources is effective for identifying the regional differences of tourism resources and reinforcing the findings of classifications of Japan's tourism regions provided by prior studies.
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  • 小元 久仁夫
    123 巻 (2014) 1 号 p. 25-34
    公開日: 2014/03/07
    ジャーナル フリー
     A consolidated and almost horizontally stratified sand layer was exposed east and north of the Hirota site, southeastern Tanegashima after Typhoon 14 struck on September 5-6, 2005. According to previous criteria given to the above-mentioned sediments, they are identified as eolianite. Calibrated 14C age of the sediments indicated 1,670 cal BP with -5.2‰ of δ13C. Judging from the figure for δ13C, the origin of calcium carbonate that consolidated the sand bed seems to have derived from underground water percolating through dune sand. Peat and outer layer of the trunk sample were also collected from downstream along the Hirota River, and their calibrated ages were 530-550 cal BP and 2,070 cal BP, respectively.
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  • 須田 耕樹, 上野 健一
    123 巻 (2014) 1 号 p. 35-47
    公開日: 2014/03/07
    ジャーナル フリー
     The distribution of weather divides in Japanese winters was identified using 30-year data of the Automated Meteorological Data Acquisition System (AMeDAS) operated by the Japan Meteorological Agency. Two kinds of weather divide were defined, one is a cloudy weather divide (CWD) determined by the high-frequency grids of large gradients in the sunshine duration distribution, and the other is a precipitation area border (PAB) where the edge of daily precipitation areas frequently appeared. The CWD appeared continuously in eastern Japan along the Pacific backbone ranges, but it was discontinuous in the central mountain ranges and western Japan. The CWD also appeared in Pacific coastal areas, such as east of Kamikouchi, south of the Kii Peninsula, and southeast of Shikoku Sanchi. The PAB overlapped with the CWD distribution in eastern Japan, and it was enhanced throughout the Sekigahara-Tamba Kochi and Chugoku Sanchi areas, but the CWD in pacific coastal areas was not associated with the PAB. Most of the weather divides were caused by the winter monsoon pressure pattern, and some PABs in northwestern Tohoku and Hokkaido areas occurred with passing pacific coastal extratropical cyclones. The distribution of the weather divides in cold-winter years was dependent on the dominance of Satoyuki/Yamayuki weather patterns, and weather divides became unclear in warm winters.
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  • 小松原 琢, 小荒井 衛, 黒木 貴一, 岡谷 隆基, 中埜 貴元
    123 巻 (2014) 1 号 p. 48-68
    公開日: 2014/03/07
    ジャーナル フリー
     The 2004 Mid-Niigata Prefecture earthquake induced many landslides in the Higashiyama Hills, central Japan. The epicenter of the earthquake was near the axis of an active fold called the Higashiyama anticlinorium, but the density of earthquake-triggered landslides was relatively low around the anticlinorium's axis. In contrast, landslide density was high on both limbs of the anticlinorium. This study analyzes the factors responsible for this difference in earthquake-induced landslide density from the viewpoints of landform development and microgeomorphology. The folding of the Higashiyama anticlinorium since the latest early Pleistocene has been uplifting the Higashiyama Hills; the 2004 earthquake was one event of this crustal movement. Microgeomorphological classification using a 2-m-mesh DEM around the middle fork of the Imo River indicates that landslide density is high on the steep slopes of the river valley, which are dissected by down-cutting of the Imo River and its tributaries. In contrast, the area around the axis of the Higashiyama anticlinorium is characterized by deep-seated landslide geomorphology, without dissecting valleys, and relatively low relief. As a result, earthquake-induced landslides are sparse there. These differences in slope geomorphology reflect geomorphic processes in actively uplifting hills and mountains with active folding. This viewpoint is applicable to estimating the potential for co-seismic landsliding.
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短報
  • 松山 洋, 稲村 友彦, 泉 岳樹
    123 巻 (2014) 1 号 p. 69-81
    公開日: 2014/03/07
    ジャーナル フリー
     Based on a questionnaire survey, this study investigates how local residents regard the strong local wind Matsubori-kaze, which occurs at Mt. Aso in Kumamoto prefecture. We distributed questionnaire sheets to students of Ozu-Higashi Elementary School, where Matsubori-kaze frequently occurs, and received 25 responses from their families. The collection rate was 71%.
     Application of quantification theory type III to overall replies to six questionnaires reveals that recognition of Matsubori-kaze by local residents was explained primarily according to their experiences with this strong local wind. However, duration of residence in this region was not related directly to the overall responses. The recognition of Matsubori-kaze differed between duration of residence of 31-45 years and that of 61-75 years. Analyses of key words used in responses from the respective groups reveals that the former (duration of residence of 31-45 years) had a strong adverse perception of Matsubori-kaze in the outdoors, whereas the latter (duration of residence of 61-75 years), which was engaged mainly in agriculture, had a fatalistic acceptance of this strong local wind.
     Application of quantification theory type III to 56 key words that appeared in multiple questionnaire sheets reveals that these key words can be summarized as “strength and mode of Matsubori-kaze,” “agricultural damage in areas with strong winds,” and “surrendering to Matsubori-kaze.”
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小特集「フィリピン・ルソン島のイロシンカルデラとブルサン火山の地質と最近の噴火活動(その1)」
  • 奥野 充, レナート ソリデュム ジュニア, マリア ハナ ミラブエノ, クリストファー ニューホール, 下司 信夫, 須貝 俊彦, 田中 ...
    123 巻 (2014) 1 号 p. 82-88
    公開日: 2014/03/07
    ジャーナル フリー
     The Irosin caldera located at the southeastern tip of Luzon Island in the Philippines was formed by the eruption of 41cal kBP Irosin ignimbrite. Bulusan, a post-caldera volcano, has repeated phreatic eruptions during historical times. The special issue on “Geology and Recent Eruptions of Irosin Caldera and Bulusan Volcano, Southern Luzon, Philippines (Part I)” provides various data and discussion mainly on the formation of Irosin caldera. First based on interpretations of volcanic landforms, the evolution of 84 volcanoes in the Philippines is outlined (Moriya, 2014). Fifty-six stratovolcanoes, three caldera volcanoes accompanying four post-caldera volcanoes, three lava domes, four scoria cones including two maars, four lava fields, and ten shield volcanoes are identified. The sequence of caldera-forming eruption at Irosin consists of a precursory fine ash eruption (Malobago lava dome), plinian pumice fallout, and intra-plinian flow deposits (Kobayashi et al., 2014a). Evidence of ground shaking during the plinian phase was also found. The total DRE volume of erupted tephra is estimated to be 30 km3 (VEI = 6). A gravity survey in February 1996 revealed a semi-circular feature with a steep gravity gradient in the Bouguer anomalies, which corresponds clearly to the southern rim of the Irosin caldera (Komazawa et al., 2014). The funnel-shaped depression structure of the gravity basement, which is significantly smaller than that of the topographic depression, was recognized from a three-dimensional analysis of residual gravity anomalies. The mass deficiency was estimated to be 1.1 × 1010 tons, corresponding to 40 km3 of DRE volume. Four thermoluminescence (TL) ages (36 ± 8 ka, 38 ± 10 ka, 33 ± 8 ka and 45 ± 10 ka) are obtained from the matrix and lithic fragments of the ignimbrite and co-ignimbrite ash-falls, respectively (Takashima and Kobayashi, 2014). Of these, the first two ages are in good agreement with a radiocarbon age of 41 cal kBP. A pictorial of representative outcrops is offered to provide an understanding of the geology in and around the caldera (Kobayashi et al., 2014b). Recent activity at the Bulusan volcano is described and discussed in the next issue (Part II).
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総説
  • 守屋 以智雄
    123 巻 (2014) 1 号 p. 89-122
    公開日: 2014/03/07
    ジャーナル フリー
     The evolution of 84 volcanoes in the Philippines is outlined geomorphologically on the basis of interpretations of volcanic landforms using aerial photographs, topographic maps, satellite images, and geomorphological and geological field surveys. Fifty-six stratovolcanoes, three caldera, three lava domes, four scoria cones, four lava fields, and 10 shield volcanoes are identified. Large basaltic volcanoes such as lava fields and shield volcanoes were found unexpectedly in subduction zones. No lava field or shield volcano has been discovered on the Japanese Islands. Among the 34 subduction zones in the world, 19 do not have lava fields or shield volcanoes. Two oblique subduction zones form the Philippine Fault Zone. The fault zone mostly coincides with the eastern volcanic zone. At the southwestern part of Mindanao Island, a volcanic chain, consisting of Bulibu, Basilan, and Cagayan Sulu lava fields, Balatukan, Mangabon, Katangrad, Kalatungan, Makaturing, Bacolod, and Pagayawan shield volcanoes, and Pagadian lava domes (monogenetic volcanoes) trends northeast-southwest, in parallel with the trenches and main arcs. The association of the volcanoes with the trenches and arcs suggests that the volcanic chain is a marginal sea ridge between Sulu Sea and Celebes Sea and that the back-arc basin ridge might have extended under Mindanao Island from Moro Gulf to the northern part of Mindanao Island.
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論説
  • 小林 哲夫, マリア ハナ ミラブエノ, マリア アントニア ボルナス, 鳥井 真之, エドアルド ラグエルタ, アルトロ ダアグ, エリク ...
    123 巻 (2014) 1 号 p. 123-132
    公開日: 2014/03/07
    ジャーナル フリー
     フィリピン共和国,ルソン島南東端のソルソゴン地域での41 cal kBPの大規模火砕流噴火の結果,11 × 11 kmのイロシン(Irosin)カルデラが形成された。このときの噴火は,カルデラを形成する大規模噴火とその先駆的な噴火の2つに区分される。
     先駆的噴火は,現在のカルデラ縁の南東斜面の小規模溶岩ドームであるマロバゴ(Malobago)溶岩ドームの形成と細粒火山灰の噴出からなる。ほかにも類似した溶岩の流出がカルデラ内にあったかもしれない。
     地質学的短期間(およそ10年以内)の休止後,3つの噴火フェーズからなるカルデラ形成噴火がはじまった。最初の噴火フェーズは,現在のカルデラ内でおこったプリニー式噴火であり,バルク体積約 20 km3の軽石質テフラが北方に拡散した。プリニー式噴火の早い段階で噴煙柱の崩壊が繰り返し発生し,intra-plinian火砕流が薄い細粒火山灰と降下軽石層に挟在している。プリニー式フェーズの終わりごろにソルソゴン地域に強い地盤振動があり,プリニー式噴火による堆積物の上下面に撹乱構造を形成した。
     イロシン火砕流の噴火は,グランドレーヤーを基底部に伴う下部ユニット火砕流の噴出ではじまった。そして,それに続く破局的な噴火によって上部ユニット火砕流が噴出し,現在のカルデラ地形を形成した。上部ユニットは,厚く粗粒な火砕流堆積物であり,基底部に粗粒な岩片濃集層(地点Dで厚さ約 2 m)が認められる。イロシン火砕流のバルク体積は,およそ 25 km3と見積もられる。
     マヨン(Mayon)火山西麓のイナスカン(Inascan)スコリア丘の山頂部で,イロシン火砕流に伴う降下火山灰(co-ignimbrite ash-falls)が発見されている。ここでの火山灰層は,層厚約1mで細粒火山ガラスと少量の斑晶鉱物からなる。比較的粗粒の最下部層は,プリニー式降下軽石層の遠方相に対比される。これらの降下テフラも含めたイロシンカルデラから噴出した火砕物全体のバルク体積は,ほぼ 70 km3に達する。
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  • 駒澤 正夫, ホセ パンティーク, エディー リスタンコ
    123 巻 (2014) 1 号 p. 133-142
    公開日: 2014/03/07
    ジャーナル フリー
     イロシンカルデラの地下構造を把握するため1996年2月にBulusan火山およびその周辺で重力調査を実施した。測点は標高の低い山麓の道沿いに限られ,測定数は225点となった。火山の山体に近い密度である 2,300 kg/m3(2.3 g/cm3)の仮定密度のブーゲー異常図は,山体部に測点がなくても実際の重力異常を表すと考えられる。重力異常にはカルデラ壁に対応する急勾配がBulusan火山の東から南を経て西に存在することがわかった。しかし,カルデラの北縁については勾配構造が明瞭ではなかった。Irosin townは急勾配構造の内側にある低重力異常域にある。重力の3次元解析から得られた重力基盤にはカルデラ壁を含むカルデラ領域を示す直径 15 kmほどの円形構造があることがわかった。さらに,その円形構造の内側には直径 5 kmほどの急勾配の壁で仕切られた漏斗状(上下逆さまの円錐)の構造が存在し,深さは 1.5 kmに達することがわかった。つまり,イロシンカルデラは,陥没構造が一カ所だけ確認でき,大量の火山砕屑物の噴出を伴った大規模噴火(複数回の場合も含む)は,ごく狭い領域に限られることを示している。また,重力異常による質量欠損の計算から約 40 km3の領域から1.1 × 1010 トンの火山砕屑物を噴出したと推定され,既存のカルデラの直径と質量欠損の関係と整合的である。
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短報
  • 檀原 徹, 奥野 充, 山下 透, マリア ハナ ミラブエノ, 鳥井 真之, 小林 哲夫
    123 巻 (2014) 1 号 p. 143-152
    公開日: 2014/03/07
    ジャーナル フリー
     Irosin ignimbrite (41 cal kBP) and its related deposits were the first widespread tephra recognized in the Philippines. This paper describes petrographic properties such as the particle composition and refractive index of the volcanic glass, in order to understand the nature of the eruption that emplaced these deposits. Green hornblende, cummingtonite, and biotite were observed in most of the samples analyzed, but green hornblende was not observed in some pumice clasts from the ignimbrite. However, it occurred in the matrix of the ignimbrite, co-ignimbrite ash, and plinian pumice samples. These results are probably due to small amounts of green hornblende phenocryst in the pumice fragments. The coexistence of cummingtonite and biotite in pumice indicates differences in crystallization conditions within the magma reservoir. A basal ash from the Malobago lava dome that preceded the ignimbrite eruption contains isolated crystals of orthopyroxene and irregular glass shards. The pumiceous deposit within the caldera shows slightly different petrographic properties (e.g. wider range of refractive index) from the other samples, which supports the interpretation of Irosin ignimbrite being reworked within the caldera.
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  • 高島 勲, 小林 哲夫
    123 巻 (2014) 1 号 p. 153-158
    公開日: 2014/03/07
    ジャーナル フリー
     イロシンカルデラ形成に関係した火砕流堆積物と同源降下火山灰の熱ルミネッセンス(TL)年代を測定した。試料は,火砕流堆積物の細粒部分2個(IrTL-01と-02),直径約 10 cmの岩片1個(IrTL-03),噴出源から約 80 km離れた降下火山灰1個(IrTL-04)の計4点であり,地質学的に同一層準のものである。得られたTL年代は,IrTL-01が35 ± 8 ka,IrTL-02が37 ± 10 ka,IrTL-03が33 ± 8 ka,IrTL-04が45 ± 10 kaである。IrTL-01と-02のTL年代は近い値を示し,火砕流堆積物中の炭化木片のAMS 14C年代から得られた41 cal kBPとほぼ一致する。岩片を測定したIrTL-03の年代はやや若くなっており,フェーディング等の誤差要因の寄与が考えられる。降下火山灰であるIrTL-04の年代は,逆に古い値となっており,試料が細粒火山灰のため,年間線量を少なく見積った可能性が考えられる。今後は,できるだけ誤差要因の少ない試料の選択と厳密な測定により,精度の高いTL年代を得る必要がある。
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