著者

小泉 格

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.116, no.1, pp.62-78, 2007-02-25 (Released:2009-11-12)

参考文献数

69

被引用文献数

7 8

---

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, Td' = (frequency of warm-water species) - (frequency of warm-and cold-water species) -1?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 Td' values correspond to a period of climatic deterioration under which cultural changes occurred in Japan. The paleoclimatic variations and the triple events of high 14C in the atmospheric residual 14C record denoted by Stuiver et al. (1991) are recognized in the diatom variations.A similar periodicity is also recognized in North Atlantic drift ice (Bond et al., 2001), concentrations of sea salt and terrestrial dust in the GISP2 ice core (O'Brien et al., 1995), in lake deposits from the Jura in France (Magny, 1995), Tibet (Gasse et al., 1991; Ji et al., 2005), and Alaska (Hu et al., 2003), and oxygen isotope variations from stalagmites in southern China (Wang et al., 2005) and Oman (Neff et al., 2001).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 T2 event in the T1-T4 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 T3 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.In the south-to-north transect of the cores from both the Pacific and Japan Sea sides of Honshu, Td' 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

吉田 明夫

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.103, no.3, pp.201-206, 1994-06-25 (Released:2009-11-12)

参考文献数

17

被引用文献数

1

---

Correlation between earthquakes in Kanto region and intermediate-depth earthquakes in Hida region, central Japan is re-investigated. We found that a significant correlation exists between earthquakes with depth of 70 km and deeper in western Kanto and intermediate-depth earthquakes in Hida region, but such a correlation is not seen for earthquakes in eastern Kanto. This result shows that earthquakes occurring in the Pacific slab are well correlated each other, but earthquakes which occur in relation to the subduction of the Philippine Sea plate are not correlated with intermediate-depth earthquakes in the Pacific plate. Intermediate-depth earthquakes in Hida region have a tendency to precede earthquakes in western Kanto. This feature may be related to the dynamics of the plate motion which oceanic plate is pulled by the subducted slab.

著者

早川 由紀夫 小山 真人

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.106, no.1, pp.102-104, 1997-02-25 (Released:2009-11-12)

参考文献数

10

被引用文献数

4 1

著者

香川 雄一

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.110, no.3, pp.314-338, 2001-06-25 (Released:2009-11-12)

参考文献数

50

被引用文献数

5 1

---

Recently, studies of industrial spaces have taken several perspectives. For example, a Locality study, especially in the United Kingdom, studies not only economic aspects but also social and political aspects.This paper discusses the changing locality of the industrial city of Mizushima, Okayama pref. which was industrialized in a period of high economic growth. The indicators of a locality study are working and social trends, and the results of elections. However it is difficult to use same indicators for a Japanese industrial city, because locality research may be unique to English cases. Pollution problems, which had been a special topic of debate in local politics, are used as the indicator for industrialization. The topics of members of the assembly, which are recorded in proceedings, are important pointers to the change from an agricultural and fishing village to an industrial city.When it was an agricultural and fishing village (pre-modern period) there were such developments as a new rice field at Mizushima located beside the mouth of Takahashi-river. These are the bottom of industrial area, now. During World War II, a munitions factory was constructed on land reclaimed from the Takahashi river. Air raids destroyed most of the factories. After the war, Okayama pref. decided to invite many large companies. Machine, petrochemical, and steel manufacturing plants began operations. The resulting industrial complex made Mizushima an industrial city.In terms of social structure, old leaders retained power until the agricultural and fishing villages combined to form Kurashiki city. Kojima city and Tamashima city also combined to form part of Kurashiki city. In those areas, old industries supplied a large part of employment. Therefore, it has taken time to change urbanize communities while increasing the population through the inflow of workers for large factories.Secondly, to clarify local politics, there has been debate on pollution problems. Incidentally, labor movements, which are thought to be important in a locality study, did not have much influence on the pollution problems in Mizushima. The first pollution problems occurred with fish and crops. So farming and fishery organizations claimed compensation for damage. Furthermore, pollution problems harmed human health as industrial spaces grew. From the 1960's to the 1970's most Japanese industrial cities had anti-pollution movements, as was the case in Mizushima. There were neighborhood associations and working organizations forming anti-pollution organizations. These spread to form a network organization in Mizushima. Eventually, the anti-pollution movement was restricting to patients with diseases caused by pollution and their supporters. These changes can be seen in the proceedings about pollution problems.At the beginning of the period with pollution problems, there were debates about industrial change, damage to local people, and policy between parties. After pollution problems increased, this topic was shared by all of the inhabitants of Kurashiki city. The debate concentrated on pollution problems, regardless of resident or party or occupation. This led to an administrative policy for the pollution problem. Then pollution damage gradually decreased. The debate moved from pollution to environment problems, which also contains protection of nature, in the latter period. There was much debate by members of the assembly in a local reformist party, and residents of Mizushima were very concerned about improving the environment of living spaces affected by pollution problems.In conclusion, industrialization and urbanization in Mizushima not only involve construction of factories and increase of industrial labor, but urbanization also refers to the living environment sought by local residents.

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 6

---

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.

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

遠藤 匡俊

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.113, no.3, pp.421-424, 2004-04-25 (Released:2009-11-12)

著者

藤原 義弘

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.112, no.2, pp.302-308, 2003-04-25 (Released:2009-11-12)

参考文献数

23

被引用文献数

4 4

---

The bacterial endosymbionts of the solemyid clam Acharax johnsoni and the thyasirid clam Parathyasira kaireiae, collected from the Japan Trench, were characterized. Transmission electron microscopic observations showed numerous bacteria in the epithelial cells of the gill tissues of A. johnsoni. Numerous bacteria were also visible in the gill tissues of P. kaireiae, but were not located within the epithelial cells. Phylogenetic analysis based on the 16S ribosomal RNA gene sequences from the gill tissues of both clams indicated that the bacteria were related to sulfur-oxidizing endosymbionts from deep-sea chemosynthetic environments. The symbiont of A. johnsoni formed a monophyletic group with the thioautotrophic symbiont of Solemya reidi, which lives relatively deeper than other solemyid clams. The symbiont of P. kaireiae formed a monophyletic group with symbiont II in Maorithyas hadalis, which lives in the hadal zone of the Japan Trench. In addition, four vesicomyid species living relatively deeper than other vesicomyid clams also have a specific clade of thioautotrophic symbionts. Bacterial chemotrophic endosymbionts as well as the mode of symbiosis might influence host distributions in deep-sea chemosynthetic ecosystems.

著者

榎本 祐嗣

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.108, no.4, pp.433-439, 1999-08-25 (Released:2009-11-12)

参考文献数

22

---

One of the intriguing events accompanying large tsunamis, especially those that strike the Pacific coasts of Japan, is the luminous phenomenon; many historical Japanese documents have described how fire balls or pillars of fire seemed to come out from the sea when tsunami approached. Among 17 events of large tsunamis from 684 to 1946, where the surface wave magnitude was greater than 8 or the tsunami magnitude was greater than 3, nine tsunami events accompanied luminous phenomena. In spite the event's high probability, few explanations have been offered as to the source mechanism except luminescent planktonic organisms, which is hardly plausible because luminous tsunamis have been eye-witnessed even in the winter season when such planktonic organisms are less active, and even in the daytime when the intensity of light emitted from planktonic organisms is unlikely to exceed the day-time brightness.Most tsunami earthquakes are thought to be associated with sediments in the accretionary prism. One recent important finding is that large volumes of stable methane hydrate are present within ocean-floor sediments at water depths exceeding about 500m at lower temperatures. When the equilibrium conditions of coupled low temperature and moderate hydrostatic pressure are disturbed by an earthquake, the hydrate abruptly decomposes. Conversely, a breakdown of hydrate may cause a further mass movement, and a cascading chain of events may occur. Some eye-witness reports in historical documents strongly suggest that luminous phenomena associated with tsunami are attributable to methane hydrate disruption, not others causes such as luminescent planktonic organisms.

著者

高田 亮

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.110, no.2, pp.245-256, 2001-04-25 (Released:2009-11-12)

参考文献数

39

被引用文献数

3 2

---

Basaltic volcanoes above oceanic crust or island-arc crusts develop calderas. Upon the formation of this caldera, the collapsed volume was generally far larger than erupted volume. Caldera width, its depth, and caldera horizontal width (CR) / volcano size (VR) depend on the physical properties of an oceanic crust. The CR/VR ratio decreases away from the ridge. At Fernandina volcano, Galapagos, the elongated caldera of 3.5 km × 2.5 km was formed in 1968 during a phase dominated by circumferential fissure eruptions after a phase dominated by radial fissure eruptions. At Kilauea volcano, Hawaii, during a phase dominated by central eruptions, several drain backs of lava lake ccurred from 1800, and, finally, a caldera of 1 km in diameter collapsed in 1924. Caldera collapse seems to be inevitable because accumulated crystals and solidified magma under a volcano increases gravitational instability. According to the gravitational collapse model proposed in this paper, it is difficult to determine when, how wide, and how deep a caldera collapse will occur. The magma plumbing system expands horizontally and vertically during long-term growth. Caldera collapse should contribute to vertical growth. Horizontal growth and vertical growth are governed by physical properties of the crust beneath the volcano; the former process is dominant in Hawaii, and the latter in Galapagos. In the case of Miyakejima volcano, the caldera collapse may be triggered by dike intrusions into a region with a low probability of intrusions or by an increase in the magma supply beneath the magma chamber. At the Miyakejima eruption in 2000, the caldera of 1.5 km in diameter formed in the shallow crust; ductile mass or dense magma with crystal mush may have moved downward or northwestward in the deep crust.

著者

三上 岳彦

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.114, no.1, pp.91-96, 2005-02-25 (Released:2009-11-12)

参考文献数

7

被引用文献数

1 1

著者

府川 宗雄

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.105, no.6, pp.709-717, 1996-12-25 (Released:2009-11-12)

参考文献数

19

被引用文献数

4 4

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 20

---

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

太田 陽子 小田切 聡子

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.103, no.3, pp.243-267, 1994-06-25 (Released:2009-11-12)

参考文献数

40

被引用文献数

4 8

---

1) 土佐佐賀から千尋岬東方にいたる地域の海成段丘を高位から H1, H2, H3, M, Lに分類した。M面およびそれより高位の段丘の形成は氷河性の海面変化に伴っており, M面は最終問氷期最盛期 (約125ka, 酸素同位体ステージ5e) の海進期に形成された。 H2, H1はそれぞれステージ7, および9の間氷期に対応する海進期を示す可能性があるが年代を確定できない。L面はさらに細分され, L1が完新世海進高頂期を, L2以下の面はその後の間欠的隆起を示している。2) 本地域は北西に低下する二つの傾動域 (伊の岬変動区と足摺変動区) に分かれ, それぞれの地域内ではH1面形成期以降の約3°万年間同様式の傾動が続いていた。M面形成期以降の最大平均隆起速度は 0.55m/ka (足摺岬) である。3) 二つの変動区の形成はプレート境界から分岐した断層の活動に由来すると思われる。伊の岬変動区はおそらく伊の岬断層を震源断層として形成されたと推定できるが, 足摺変動区の傾動を説明する震源断層を特定することはできなかった。細分される完新世段丘群はこれらの分岐断層の最近の活動史を記録しており, 上記両変動区で隆起時期を異にしている。

著者

中井 順二 駒沢 正夫 大久保 泰邦

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.96, no.4, pp.185-200, 1987-08-25 (Released:2009-11-12)

参考文献数

15

被引用文献数

2 2

---

Bouguer anomaly map of the Kanto district was compiled. On the whole, gravity anomalies are high in Tsukubasan areas, and low in the central parts of the Kanto plain. Negative anomalies in the Boso peninsula and the Tama hills suggest the basement structures of the sedimentary basins. The Kanto mountains district is bounded on the east by steep gradient of gravity anomaly. The above gravity features can be recognized in the map of the upward continuation. The gravity trend along Narashino, Sakura and Omigawa is more clearly indicated in the map of the first derivative, and the tectonic line covered by sediments can be supposed.In the Izu peninsula and the Tanzawa mountains district, gravity anomalies are rather high and low anomaly zone is recognized between these two areas. The northern border part of this zone correspond to Kannawa fault and Kozu-Matuda fault.Aeromagnetic map was compiled with the data obtained by New Energy Development Organization and Geological Survey of Japan.Generally, the Kanto district is surrounded by intense magnetic anomalies with short wavelength which are distributed along Nasu volcanic zone and Fuji volcanic zone.In the central part of the Kanto plain, weak magnetic anomalies are scattered zonally in the E-W direction. According to the geological and well data, this zone seems to be corresponded to Sambagawa metamorphic belt and these anomalies are presumably caused by the basic or ultrabasic rocks.The Hakone mountains district has sharp anomalies with short wavelengths, and the maximum amplitude of the anomalies reachs 900nT. Low anomaly zones are recognized arround this high anomalies. The source of this low anomalies is not clear, but it is of great interest geologically and geophysically.

著者

跡部 治

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.84, no.1, pp.41-45, 1975-02-28 (Released:2009-11-12)

著者

河村 公隆

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.98, no.6, pp.791-797, 1989-12-05 (Released:2009-11-12)

参考文献数

35

著者

福山 博

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.92, no.1, pp.55-67, 1983-02-25 (Released:2010-10-13)

参考文献数

11

被引用文献数

3 4

---

Minami-Iwo volcano is located at the southern end of Izu-Bonnin volcanic chain, 1300km south of Tokyo. It consists of three major volcanic edifices; older volcano I (OV1), older volcano II (OV2), and younger volcano (YV). At the boundaries between OV1 and OV2 and OV2 and YV, pyroclastic materials are characteristically observed; scoria fall deposit between OV1 and OV2, and scoria fall deposit and pyroclastic flow deposit between OV2 and YV. Older volcanoes, OV1 and OV2, are wholly composed of lava flows with both aa and pahoehoe surface textures. Younger volcano (YV), on the other hand, consists mainly of scoriaceous agglutinate which made up the steep slope of the main Minami-Iwo volcano. The older volcanoes are cut by numerous dikes (115 all told) which are dominant at the south and southwest sea cliffs. Four specimens collected from OV1, OV2 and dikes show normal thermoremnant magnetic orientation suggesting the oldest age less than a few hundred thousand years. Rocks of Minami-Iwo volcano are ankaramite, olivine basalt, augite-olivine basalt and plagioclase phyric basalt. The petrographic features and the chemical composition show that the rocks of Minami-Iwo volcano are of alkali rock series. The basalt of alkali rock affinity is the first discovery for volcanoes located at the volcanic front in Japan.

著者

町田 洋 新井 房夫

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.88, no.5, pp.313-330, 1979-10-25 (Released:2009-11-12)

参考文献数

49

被引用文献数

45 27

---

The eruptions of the Daisen Valcano (35°22'N, 133°33'E) were mainly rhyodacitic and of the paroxysmal type, producing several extensive sheets of tephra. The Kurayoshi pumice (DKP, for short), one of the excellent Late Pleistocene markers arising from the Daisen valcano, is rhyodacitic in composition with abundant hornblende and orthopyroxene crystals and relatively small amount of biotite. Its identification can be made from the above mentioned mineral assemblages as well as from the characteristic refractive index of orthopyroxene (γ=1.703-1.708) and of hornblende (n2 = 1.673-1.682) and the specific crystal habit of orthopyroxene. This pumice-fall deposit occurs on marine and fluvial terraces in the San'in and Hokuriku districts facing the Japan sea and extends eastward beyond the Northern Japan Alps to north Kanto plain as a thinner discontinuous layer. Stratigraphic relation with the dated tephra layers in north Kanto indicates that the pumice was probably deposited between about 47, 000 and 45, 000 years ago. That is, this pumiceous deposit is found at the intermediate horizon between Yunokuchi Pumice (UP, slightly younger than 49, 000 YBP) and Hassaki Pumice (HP, 40, 000-44, 000 YBP) in north Kanto, about 500 km far from the Daisen.Daisen Kurayoshi Pumice wonld be particularly valuable for establshing chronological framwork as a fundmental time-marker in arears where no suitable markers have yet been documented. Moranic deposit of the Murodo glacial advance at Mt. Tateyama, Northern Japan Alps, is mantled by this marker and overlies the Raicho-dai pumice-fall deposit, products of the earliest stage of volcanic activity of Tateyama III, which is correlated with the Omachi EPm deposit approximately 60, 000 years old. Distribution of these two unreworked tephras indicates that major valley glaciers had nearly disappeared by the times of these initial tephra falls. The glacial advance at Mt. Tateyama, the most extensive of the advances during Last Glacial age, therefore, apparently culminated between about 55, 000 and 50, 000 years ago. On the other hand, a filltop terrace repesented by Uwadan terrace along the River Joganji flowing from Mt. Tateyama, is covered by DKP and is nearly younger than the pyroclastic flow deposit of Tateyama III. Accumulation of the river of Uwadan stage is, therefore, simultaneous and probably associated with the Murodo glacial advance.

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