著者
山川 修治
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.102, no.2, pp.183-195, 1993-04-25 (Released:2010-11-18)
参考文献数
60
被引用文献数
1 1

Natural disasters in Little Ice Age (c. 1550-1850) and its climatic variations which formed a significant background for the disasters are mentioned. Cool summers due to a prevailing Okhotsk High were characteristic of this period. Cold winters, summer heavy rains and unstable atmospheric conditions also constituted essential features of Little Ice Age. Aerosol ejected by a series of major volcanic eruptions partly prevented solar radiation from reaching the earth' s surface (parasol effect), which resulted in cool and unusual weather. Agriculture, in particular, was vulnerable to bad weather damage. As a result of decreasing direct insolation, sometimes together with lowering temperature and/or locally increasing precipitation, seven major famines occurred during the Edo Era (1663-1868) which approximately coincided with Little Ice Age. Several cases in this paper suggest that natural environment in Little Ice Age was marked by both volcanism and weakened solar activities which “Maunder Minimum”(1645-1715) represented.
著者
西上 欽也 田所 敬一 永井 悟 水野 高志 加納 靖之 平松 良浩
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.111, no.2, pp.268-276, 2002-04-25 (Released:2009-11-12)
参考文献数
21
被引用文献数
1

This paper briefly reviews the triggering characteristics of injection-induced seismicity. Water injection experiments were carried out in the Nojima fault, southwest Japan in 1997 and 2000 to detect the healing process of the fault zone after being ruptured by the MJMA 7.3 Hyogo-ken Nanbu (Kobe) earthquake in 1995. During the experiment in 2000, ultramicroearthquakes of M-1.2 to 1.0 were induced at about 2.5-4.5 km from the injection point and about 4-6 days after the beginning of injection. This space-time migration can be explained by a 2-D diffusion process of pore water pressure. Permeability estimated near the surface, at about 540-800 m depth, is extrapolated well to a depth of 2-4 km where induced events occurred. Other experiments at Matsushiro, central Japan and KTB, Germany also showed similar space-time relationships of induced seismicity. From observations in the Nojima experiment, we obtained characteristic states that suggest differences in the generating process between induced and normal (tectonic) earthquakes. Our findings are as follows : (1) high-frequency component is richer in the waveforms of tectonic events, and (2) the clustering of hypocenters is more dominant in induced events. Further analyses of these observations will lead to elucidating the generating process of induced earthquakes by increasing pore water pressure.
著者
新井 健司
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.104, no.2, pp.267-283, 1995-04-25 (Released:2009-11-12)
参考文献数
17
被引用文献数
1 1

Plio-Pleistocene fluvial sediments are distributed in the hills along the western margin of the Kanto Plain. In this paper, the author reports its sedimentary environments at Hidaka City, Saitama Prefecture, namely, those of Yaoroshi tuff, Hanno gravel and their correlatives.The basement in this area (Chichibu Paleozoic and Mesozoic formations and Takaoka formation) is divided into three zones structurally by Koma-Hongo and Komagawa fault systems. And terrace deformation dipping toward the Kanto Plain is recognized on its surface.Yaoroshi tuff is in fault or unconformity contact with the basement in part of Koma-Hongo fault system. The vertical displacement of each fault system is over 50 m. Yaoroshi tuff is not distributed in west of Koma-Hongo fault system.Hanno gravel, conformably overlying Yaoroshi tuff, is in fault or unconformity contact with the basement. Hanno gravel and its correlatives were formed by old long rivers, of and the valley bottoms were at least 140 m above sea level in Koma River system area and at least 150 m above sea level in Shukuya River system area.Boulders of granite and diorite characterizing Hanno gravel in the south of Tenran-zan (Mt. Tenran) are not found in the investigated area. This fact suggests that the area was in different conditions of sedimentation from the southern area. The ridge directions of Koma Hills and Moroyama Hills had already settled before dissection proceeded.The gravel from Moroyama Hills and the adjacent areas is divided into the lower and the upper layers. The former is correlated with Yaoroshi tuff, while the latter with Hanno gravel.When Yaoroshi tuff deposited, forested stable land had extended widely. And short rivers flowing out from near mountains sometimes flooded and destroyed forests. After Yaoroshi tuff was formed, long rivers transported boulders with sands in large quantities from distant western mountains. These old long rivers kept their main courses to the present as Koma River system and Shukuya River system, and they mixed gravels by gathering currents and forming talus deposits.
著者
相馬 清二
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.84, no.4, pp.204-217, 1975-08-25 (Released:2009-11-12)
参考文献数
8
被引用文献数
3 2

A violent fire-tornado has broken out at the former site of the Army Clothing Depot in combustion caused by the destructions of the Great Kanto Earthquake at 3.30 p.m. September 1, 1923. By this fire-tornado, about 40 thousand people have been burned to death in a moment. An interpretation that the fire-tornado has been caused by passage of a cold front has generally dominated academic circles in this field up to date. According to the detailed reexaminations, this interpretation included many inconsistencies. We could obtain recently the various data with respect to the fire-tornado which occurred in the last several years. From these data, it became clear that the fire-tornadoes often have occurred near a combustion area.An example which was the most similar with the fire-tornado at the former site of the Army Clothing Depot was found out in the combustion of Wakayama City by an air raid on July 9, 1945. 748 persons have been burned to death by the fire-tornado in this city.Finally, our study leads to the conclusion that the fire-tornado at the former site of the Army Clothing Depot was caused by the widespread great fire following the Great Kanto Earthquake. There was a cold front in northwestern direction of Tokyo, but it did not play the leading role for formation of the fire-tornado.
著者
Mitsuhisa WATANABE
出版者
Tokyo Geographical Society
雑誌
Journal of Geography (Chigaku Zasshi) (ISSN:0022135X)
巻号頁・発行日
vol.116, no.3-4, pp.387-393, 2007-08-25 (Released:2009-11-12)
参考文献数
20
被引用文献数
3 5

The cabinet office of the Japanese government demonstrated the prospects of future seismic hazards associated with a working model for possible earthquakes in the capital area of Japan. If this assumption is not unrealistic, it is reasonable to use this working model. However, it has already been reported that several active faults may exist in this area. This discrepancy can lead the assessment into unreal issue.I reveal the nature of the Ayasegawa fault located close to the capital area on the basis of geomorphic features. The fault extends in the NWSE direction for at least over 30 km, and the fault trace is linear, which is indicative of lateral movement. There is a graben structure delineated by the fault in the Minuma ward, Saitama City. The vertical component of the Ayasegawa fault is upthrown to the southwest and the average vertical slip rate is 0.05 to 0.1 m/ky. The netslip rate should be much larger than the vertical one, taking lateral movement into account. Although the single vertical offset is assumed to be 0.8 to 4 m, the rupture history of the fault remains unknown.The Ayasegawa fault is an southeastern extension of the Fukaya fault, and is composed of an active fault extending more than 120km through the Kanto Plain across the capital area of Japan. To prepare for a real seismic hazard and to try to reduce damage, we should check the properties and clarify the rupture history of these active faults as an urgent task. Precise local information on these active faults is necessary for motivating people to develop an awareness of disaster mitigation.

5 0 0 0 熊本の地震

出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.6, no.9, pp.520b-520b, 1894
著者
大森 房吉
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.32, no.3, pp.116-124, 1920
著者
齋藤 有 田村 亨 増田 富士雄
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.114, no.5, pp.687-704, 2005-12-25
被引用文献数
3 3

Hyperpycnal flow is one type of turbidity current, which is generated at a river mouth when the suspended sediment concentration of river discharge is so high that the density of the effluent exceeds the water of the receiving basin. Generations of this type of flow have become a common phenomenon recently. A lot of hyperpycnal flow deposits are expected to be preserved naturally in stratigraphic records. Hyperpycnal flow deposits (hyperpycnites) might become an innovative factor for turbidite paradigm considering the particularity of the flow, and bring facies analysis towards the next step. In this review paper, the criteria for identifying hyperpycnal flow deposits from strata are proposed by summarizing studies on hyperpycnal flow and its deposits. Typical characteristics of hyperpycnal flow include : (1) vertical succession composed of 2 parts, inversely-graded lower part and normally-graded upper part, (2) internal scour surface, (3) repetitive alternation of fine-grained and coarse-grained layers, or laminated and massive layers, (4) abrupt pinch-out of beds, and (5) inclusion of terrestrial materials such as leaves. Hyperpycnal flow gradually waxes and then wanes to terminate in response to flood conditions, resulting in (1). The internal scour surface (2) developed in accordance with the degree of waxing. Fluctuations of flow velocity and sediment concentration due to changes of river discharge and/or internal waves can occur during the flow event, and lead to repetitive alternation of (3). Because of the fresh interstitial water, the marine hyperpycnal flow might start to lift off after losing suspended sediments to the degree that the density of the flow is exceeded by ambient saline water. This results in (4) at the lifting point. Terrestrial materials referred to in (5) are the result of the fact that the hyperpycnal flow originated from terrestrial floods.<BR>A much wider variety of deposits, which form in one history of a turbidity current, than that expected from the Bouma sequence model, is shown. Exploration of the variety has just started.
著者
田切 美智雄 森本 麻希 望月 涼子 横須賀 歩 DUNKLEY Daniel J. 足立 達朗
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.119, no.2, pp.245-256, 2010-04-25
参考文献数
29
被引用文献数
8 15

Hitachi metamorphic rocks located in the southern part of the Abukuma Mountains, Northeast Japan, distinctively contain meta-volcanic rocks and meta/sheared granitoids. The igneous ages of meta-granite and meta-porphyry from the Hitachi metamorphic rocks were determined by the SHRIMP zircon method. In this paper, we describe occurrence, petrography, and petrochemical characteristics of these studied rocks. Meta-porphyry, with an igneous age of 506 Ma, intrudes into the meta-volcanic rocks of the Akazawa Formation of the Hitachi metamorphic rocks and has a micrographic texture and a spherulitic texture of an igneous origin. Previous studies have already reported an igneous age of 491 Ma for meta/sheared granitoids using the SHRIMP zircon method. Cambrian meta/sheared granitoid samples occur widely as a granitic body in the northeastern part of the Hitachi metamorphic rocks. (A) Meta-granite of the same age (498 Ma) as the sample used for the above dating is found as boulders in meta-conglomerates. The meta-conglomerate, which is found in the Daioin Formation of the Hitachi metamorphic rocks, lies unconformably on a Cambrian meta-granite body. Both meta-volcanic rocks and meta/sheared granitoids have chemical characteristics commonly associated with island arc volcanism. As such, the Akazawa Formation is likely to have originated in the Cambrian era, although we have no SHRIMP age for meta-volcanic rocks of the Akazawa Formation.
著者
岡田 篤正 安藤 雅孝 佃 為成
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.96, no.2, pp.81-97, 1987-04-25 (Released:2010-02-25)
参考文献数
35
被引用文献数
6 2

Four trenches (Trenches A-D) were explored across the Yasutomi fault (a strand of the Yamasaki fault system) to date recent past faultings. Trench A was 3 m deep and 28 m long across the fault (Upper in Fig. 3 and Fig. 4), and the additional excavation was made down to 5 m deep (Fig. 5) from the western wall of trench A. The sizes of other tenches are similar to that of trench A. Since this site was being developed after this trenching for the building lot of a factory, many pieces of important geological evidence were gradually exposed with progress of the construction. This enabled us to make a further detailed geological and geomorphological study of the Yasutomi fault. The results are summarized as follows : 1) Yasutomi fault, which has been considered to be predominantly left-slip active one estimated from tectonic morphologies, was geologically confirmed that this had dislocated with predominantly lateral-slip component at least since a few tens of thousand years.2) Widely sheared zones appeared along the north side of the active trace do not accompany any tectonic features. Therefore, this straightly trending depressional zone is to be recognized as a fault-line valley. A new fault was originated along the southern rim of pre-existed weak zone probably since the late Quaternary.3) The valley-filling deposits are disturbed at the lower part of the trench but not at the upper part this suggests that the fault has not moved since the deposition of the upper horizon although small earthquakes have been reported to occur frequently around the fault. Sense and amount of vertical offset, drugged structure and other fault features vary laterally along this, as common in high angle strike-slip fault.4) The latest displacement occurred between late 7 th and 12 th Centuries, probably associated with the 868 Harima Earthquake (M=7.1). Two more faultings were also inferred from C-14 dates of disturbed and undisturbed strata within a deformed zone of the fault, although they are less reliable. The recurrence interval of earthquakes as large as the 868 event is estimated to be at least 1000 or possibly a few thousand years along this strand of the Yamasaki fault system.
著者
田中 和広 石原 朋和
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.118, no.3, pp.499-510, 2009-07-07
被引用文献数
5 3

The Nabetachiyama Tunnel 9116 m long was excavated in Tokamachi City, Niigata Prefecture and encountered the serious difficulties during excavation. In particular, a 600 m long section in the Matsudai area had experienced difficulties caused by swelling mudstone in the Tertiary Sugawa Formation. A 120 m bore hole long was excavated in the neighborhood of the section and geological and geochemical examinations of sampled cores were carried out to investigate the formation mechanism of the swelling rock mass. Mudstone distributed deeper than 50 m in the bore hole can be correlated to the tunnel troubled section geologically and geochemically. The section is assumed to be composed of mud breccia with mudstone fragments and clayey matrix, which is thought to be generated by hydro-fracturing of mudstone, showing weak strength due to large quantities of clay minerals. A gas pressure of 1.6 MPa thought to be caused by degassing of methane was measured during tunnel construction, which would increase the swelling properties. Mud breccia distributed deeper than 50 m contains a lot of Na-smectite formed in highly saline pore water ascending from deep underground. The result of slaking test showed that mud breccia filled with saline groundwater is characterized by quick slaking and swelling due to the marked contraction of Na-smectite when drying. In summary, the swelling rock mass distributed in the troubled section was formed by the weak rock strength caused by hydro-fracturing and high gaseous pressure generated by degassing. Furthermore, quick slaking caused by repeated wetting and drying was another reason for swelling during excavation.
著者
大和 広明 三上 岳彦 高橋 日出男
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.120, no.2, pp.325-340, 2011-04-25
参考文献数
12
被引用文献数
3 8

We analyze the influence of sea breeze on temperature distribution in the Kanto Plain (central Japan) on a day that a sea breeze front was detected (known as sea-breeze front days) using high-resolution temperature data observed by our research team.<br> The high-temperature area on sea breeze front days moves northwest from central Tokyo, and was located at Kawagoe city (middle Kanto Plain) at 14 JST, and the northern Kanto Plain at 16 to 18 JST, respectively. This high-temperature area appears at the head of the sea breeze front to the leeward of central Tokyo, where the daily maximum temperature is highest in Kawagoe city and the northern Kanto Plain. After the sea breeze front passes, the area where the temperature is higher than that at the circumference is distributed in the shape of a wedge. This wedge-shaped area is located to the leeward of central Tokyo where the wind from Tokyo Bay and Sagami Bay forms a convergence zone. The high-temperature area around Kawagoe city, which cannot be found on days with strong winds, is formed from the hindrance of cold air advection caused by sea breeze front penetration.<br> On the other hand, high temperatures in the northern Kanto Plain may not be related to the penetration of sea breeze fronts, which do not reach the northern Kanto Plain on days when the daily maximum temperature is recorded. However, the temperature in the northern Kanto Plain is higher on sea breeze days than on strong southerly wind days, and this suggests that local circulation plays an important role in causing high temperatures in the northern Kanto.
著者
小泉 格
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.116, no.1, pp.62-78, 2007-02-25
被引用文献数
3 6

The results of hydro-environment researches into marine and lacustrine sediments revealed climatic variations which seem to have some relationships between turns in world history and climatic changes. In the Japan Sea and northeast Pacific off Kashima from the Late Glacial to the Holocene, diatom temperature, <I>Td</I>' = (frequency of warm-water species) - (frequency of warm-and cold-water species) <SUP>-1</SUP>?100, values show rhythmic fluctuations with durations of 1 kyr and 400-500 yrs (Koizumi et al., 2004, 2006). This indicates a strong and regular inflow of the warm Tsushima Current into the Japan Sea as a branch of the warm Kuroshio Current. The decreases of <I>Td</I>' values correspond to a period of climatic deterioration under which cultural changes occurred in Japan. The paleoclimatic variations and the triple events of high <SUP>14</SUP>C in the atmospheric residual <SUP>14</SUP>C record denoted by Stuiver <I>et al</I>. (1991) are recognized in the diatom variations.<BR>A similar periodicity is also recognized in North Atlantic drift ice (Bond <I>et al</I>., 2001), concentrations of sea salt and terrestrial dust in the GISP2 ice core (O'Brien <I>et al</I>., 1995), in lake deposits from the Jura in France (Magny, 1995), Tibet (Gasse et al., 1991; Ji <I>et al</I>., 2005), and Alaska (Hu <I>et al</I>., 2003), and oxygen isotope variations from stalagmites in southern China (Wang <I>et al</I>., 2005) and Oman (Neff <I>et al</I>., 2001).<BR>Climatic deteriorations are synchronous with periods when serious changes occurred in human intellectual achievements during the Holocene. The Agricultural Revolution (11, 000-10, 000yr BC), with the cultivation of wild plants and domestication of wild animals to produce and secure food, seems to coincide with the Younger Dryas event. Increased agricultural production made it possible to afford a population not engaged in agriculture, for example, people engaged in handicrafts, festivals, and politics. This seems to occur in the period coinciding with T<SUB>2</SUB> event in the T<SUB>1</SUB>-T<SUB>4</SUB> triplets, which have Maunder-and Sporer-type patterns occurring in sets of three, denoted by Stuiver and Braziunas (1993). The religious courtesy belief in the recycling and the reinforcing of life was converted into a rational and systematic consideration of life based on universal theory. This conversion of thinking seems to coincide with the T<SUB>3</SUB> event. Modern science was established in Europe in the 17th century. And now human beings are destroying natural environments using highly developed scientific technologies of their own. This is a negative revolution that human beings have never previously experienced.<BR>In the south-to-north transect of the cores from both the Pacific and Japan Sea sides of Honshu, <I>Td</I>' values indicate that the Kuroshio Current and Tsushima Warm Current are both weakening at present. The present interglacial period might end and become a cooler climatic condition like a Little Ice Age within 300 years. The insolation at 37°N among the Earth's orbital parameters is weak at present (Koizumi and Ikeda, 1997). However, the mean global temperature has risen about 0.5°C during the last century. Warming of the Earth, which is caused mainly by carbon dioxide in the atmosphere, has made natural environments unstable.
著者
柳井 修一 青木 一勝 赤堀 良光
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.119, no.6, pp.1079-1124, 2010-12-25
被引用文献数
8 26

Median Tectonic Line (MTL) and Fossa Magna (Itoigawa-Shizuoka Tectonic Line) had long been considered to be the most critical fault boundaries controlling development of the Japanese Islands since Naumann (1885) and Kobayashi (1941). After the appearance of plate tectonics, several new interpretations emerged, <i>e.g.</i>, sub-surface Benioff plane for the MTL. In this paper, we propose that those tectonic lines, major faults, and Tanakura Tectonic Line (TTL) were formed through a process at micro-plate boundaries during the opening of the Japan Sea in the Miocene.<br> MTL could have been formed along the consuming boundary between the PHS plate and Japan Sea microplate, which has shifted southward to the Nankai trough, accompanying large-scale tectonic erosion. Fossa Magna was formed as a gigantic transform fault with a transtension component in the Medial-Japan Sea when opening was initiated. The eastern and western boundaries of the Japan Sea must be a strike-slip fault, corresponding to TTL to the east, and a newly proposed strike-slip fault called the West Kyushu Tectonic Line, respectively. Fossa Magna, a medial region defined by two NS-trending Miocene parallel faults in central Honshu, defined by Nauman (1885) could be interpreted to be the largest transform fault in the Medial-Japan Sea to offset the spreading axis when the Japan Sea opened.<br> It should be emphasized that large-scale tectonic erosion occurred in front of consuming plate boundaries facing the PHS and PAC plates oceanward during the opening of the Japan Sea. The volume of tectonic erosion is calculated to be 17,581,500 km<sup>3</sup>, which is equivalent to 2/3 of the present-day Japan arc crust, which is sufficient to reach the depth of the megalith between the upper and lower mantle boundary, even with 10 km thickness of materials eroded and transported along the Benioff zone.<br> Although MTL, Fossa Magna, and TTL are remarkable in the geology of Japan, these young faults never affected the orogeneses of Japan back to 520 Ma, which grew the continental crust of Japan. We propose that microplate boundary processes decreased the volume of the Japan crust.
著者
三雲 健
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.99, no.1, pp.18-31, 1990-02-25 (Released:2010-11-18)
参考文献数
58
被引用文献数
3 3

Extensive studies on seismic activity and focal mechanism of major to moderate-size earthquakes that occurred along the eastern margin of the Japan Sea and the northern part of the Fossa Magna regions are reviewed and discussed in relation to regional tectonics. The validity of a prevailing hypothesis is also tested from various observations to see if the Northeast Honshu arc is part of the North American plate.Seismicity along the Japan Sea coastal regions extends southwestwards across the Toyama trough in one way, and also in other way to the northern Fossa Magna through a zone near the Shinano river. It has been noticed that the seismicity show temporarily successive properties similar to migration phenomena. Five major earthquakes along the Japan Sea regions have been interpreted as having thrust-type mechanisms, and the depth distribution of aftershocks of two larger events and the dip of submarine active faults suggest an eastward dipping fault plane.The maximum compressive stress derived from the focal mechanisms of more moderatesize earthquakes indicates E-W to ESE-WNW orientations, changing gradually from the northern to southwestern part of the coastal regions. In inland regions west of the northern Fossa Magna, the general trend appears oriented again in the ESE-WNW direction, which is found to be well consistent with the direction of principal compressive strains derived from geodetic triangulation surveys over the last 80 years.All the above evidence suggests that the regions under consideration may be a tectonically active, convergent zone, and might be regarded as a zone of a possible plate boundary. There is no direct evidence, however, suggesting an eastward incipient subduction of the Japan Sea lithospheric plate, from observations of submarine topography and upper crustal structure beneath the regions.Numerical calculations show that the suggested hypothesis could partly account for the observed directions of compressive stress in Northeast Honshu but is apparently inconsistent with those in Southwest Honshu. The results suggest that the Northeast Honshu arc may better be regarded as a “micro-plate” which receives strong compressive stress not only from the westward movement of the Pacific plate but also from the west side. One of possible sources of the driving stress from the west side might be an eastward movement of the “Amurian plate” which is one of micro-plates detached from the Eurasian plate. Another possible source could be bilateral extension of the central Japan Sea region or of the regions covering Northeast China and the Korean peninsula.
著者
早川 由紀夫
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.107, no.3, pp.444-457, 1998-06-25 (Released:2009-11-12)
参考文献数
18

ハワイ島はハワイ諸島最大の島で, 群馬県と埼玉県を合わせたくらいの面積をもつ。活発に噴火を続けるキラウエアのほか, 歴史時代に噴火記録があるマウナロアとフアラライ, 4,205mの山頂まで車で行くことができるマウナケア, 山頂近くまで深い谷に刻み込まれたコハラ, の5火山からなる火山島である (図1) 。ハワイ・ホットスポットの火山活動を観察するのに最適の島だ。オアフ島のホノルルから直行便が, 東海岸のヒロと西海岸のコナへ毎日数便飛んでいる。私たちはキラウエアに近いヒロへ飛ぶことにしよう。アメリカのレンタカーは一週間単位で借りると割安だから, ハワイ島に7泊する旅行計画を立てるとよい。40ドルの乗り捨て料金を負担すれば, ヒロ空港で借りた車をコナ空港に返すこともできる。実際, 私は11人の仲間といっしょに1997年12月24日にヒロ空港に降り立ち, 南回りで移動して, 12月31日早朝コナ空港から帰国の途についた。この火山見学案内は, そのときの体験と, 過去3回の私自身のハワイ島旅行経験 (1983年, 1987年, 1991年) に基づいて執筆したものである。出発当日に旅行代理店の倒産を知らされるという困難を克服して, 9日間の旅行を実り多く, しかも楽しく終えることができたのは, 旅行に参加した群馬大学教育学部学生と卒業生みなさんの力による。なお, 旅行参加者全員の分担執筆による体験記をウェブページ (http://www.edu.gunma-u.ac.jp/~hayakawa/fieldguide/p/US/HI/hawaii 97.html) で公開している。これから現地に行く人に利用していただけたら幸いです。
著者
西尾 嘉朗 佐野 有司
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.109, no.4, pp.636-645, 2000-08-25 (Released:2010-11-18)
参考文献数
24
被引用文献数
1

Based on δ 13C values and CO2/ 3He ratios of North Fiji Back-Arc Basin basalt glasses, wediscuss the carbon geochemical cycle in the subduction zone. Among the North Fiji Back-ArcBasin basalt glasses, there is a close correlation among CO2/ 3He ratios, δ 13C value, and143Nd/ 144Nd ratios. The CO2/ 3He ratios and the δ 13C values of North Fiji Basin basalt maybe attributed to binary mixing between the mantle component (low-CO2/ 3He, high-δ 13C, andhigh-143Nd/ 144Nd) and the subducted (recycled) component (high-δO2/ 3He, low-δ13C, and low-143Nd/ 144Nd). From a simple mass balance calculation, it is derived that the subductedend-member (recycled carbon) has 70% carbonate and 30% organic matter in origin.Assuming that complete decomposition of the subducted organic matters has occurred, most (about 90%) carbonates are not decomposed, because the amounts of subducting carbonatesand organic matters throughout the North Fiji subduction zone are estimated in a ratio of20: 1. This suggests that carbonate can be transported into the mantle through the subduction zones.
著者
小林 貞一
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.98, no.1, pp.34-48, 1989-02-25 (Released:2009-11-12)
参考文献数
43
被引用文献数
1 1

In Japan 14 species in 21 genera of Carboniferous trilobites were known in 1980 and 22 species in 11 genera of the Permian ones in 1984. Adding a few species described since then, the Permo-Carboniferous trilobites of Japan total about 70 species at present. They are described from 18 horizons, namely 11 and 7 horizons respectively for the Carboniferous and Permian ones. They are compared with the faunas of the Mongolian geosyncline, Hwangho and Yangtze basins and Southeast Asia. While the Mongolian sea retreated from the west side through the periods, the route of migration was maintained toward the Mediterranean sea through the Himalayan geosyncline until the end of the Palaeozoic era. Some trilobites of Japan reveal relationship further toward the Australian and North American sides.
著者
新井 智一
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.114, no.5, pp.767-790, 2005-12-25
参考文献数
47
被引用文献数
2

This study examines the interaction between the politics in Fussa City and the Yokota Air Force Base, that is "the politics of place, " from a range of political, economic, and cultural processes which maintain the existence of the base.<BR>Military bases are generally established for global geopolitical purposes. However, the establishment of a military base has cultural implications for the local communities where the base is located, i.e., increased concerns about crimes committed by seavicepersons and noise by aircrafts. Although these military bases have some serious impacts, especially in Japan, geographers have not yet examined the issues regarding a particular military base and the resultant politics in the city.<BR>On the contrary, since the 1980s, Anglo-American political geographers have paid more attention to "the politics of place" This refers to the local politics that occur due to the interaction between a structural constraint and the individuality of a particular place.<BR>Therefore, this study examines "the politics of place" on the Yokota Air Base in Fussa City, Tokyo, by using resources from the local newspapers, novels, magazine articles, and council proceedings.<BR>The results are as follows : (1) Owing to the independence between the U.S. Air Force and local political and economic actors, an urban structure and local economy that depended on the Yokota Air Force Base were constructed in Fussa Town after the establishment of the base in 1945; (2) because of this structure, the local economy became to depend on Air Force personnel as consumers; (3) however, due to a shift to the floating exchanging rate and a reduction in the population of the base in the first half of the 1970s, there was a decrease in the influence that Air Force personnel had on the local economy; (4) since the 1980s, an economic agent utilized the "atmosphere" and "image" adjacent to the base to revitalize the local economy; (5) furthermore, the mass media represented Fussa City as a "base town" and conducted a review of the city in the 1960s, thus contributing to its revitalization; (6) during the economic slump in the 1970s, some local political agents were against the existence of the base. However, successive mayors of Fussa City have accepted the existence of the base, and utilized the subsidies it receives from the national government in order to construct the urban infrastructure.