著者

深畑 幸俊 大橋 聖和 高田 陽一郎 田中 明子

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.128, no.5, pp.685-687, 2019-10-25 (Released:2019-11-15)

参考文献数

9

被引用文献数

2

著者

磯崎 行雄

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.108, no.5, pp.643-649, 1999-10-25 (Released:2009-11-12)

参考文献数

6

著者

吉田 明夫 青木 元

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.111, no.2, pp.212-221, 2002-04-25

参考文献数

26

被引用文献数

1 2

---

We show that conspicuous seismic quiescence occurred in large areas along the coast of the Japan Sea before the 1891 Nobi, 1964 Niigata, 1983 Central Japan Sea, and 2000 Western Tottori Prefecture Earthquake. If we had noticed the quiescence that had appeared since the late 1980s along the northern coasts of Shimane, Tottori, and Hyogo Prefectures and had remembered the feature that a large earthquake in the coastal region of the Japan Sea is likely to be preceded by a widely extended seismic quiescence along the coast, we could have paid close attention to the focal region of the Western Tottori Prefecture Earthquake. We think the occurrence of seismic quiescence in a large area before a large earthquake implies that the preparatory process proceeds not only in the focal region, but in the circumferential areas as well.

著者

田村 芳彦

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.120, no.4, pp.567-584, 2011-08-25 (Released:2011-11-10)

参考文献数

73

被引用文献数

2 4

---

The tectonic setting of arc-arc collision and arc accretion in the Izu-collision zone is similar to that of the Archean orogenic belts (e.g., Taira et al., 1992). Understanding the petrological processes of granite formation in the Izu-collision zone, where geodynamic information is not modified by polyphase deformation and metamorphism, may contribute to an understanding of ancient orogenic belts, especially those related to collisional settings. The Pacific plate began subducting the Philippine Sea plate about 50 million years ago to produce the currently active Izu–Bonin–Mariana (IBM) arc. The collision between the northern IBM arc system and the Honshu arc of the Eurasia plate has been occurring since the middle Miocene (ca. 15 Ma) as a consequence of the northwestward migration of the Philippine Sea plate (e.g., Yamazaki et al., 2010). Neogene granite plutons are widely exhumed by tectonic uplifts associated with arc collision. Seismic imaging suggests that most of the present Izu-Bonin arc crust was created in the Eo-Oligocene (Kodaira et al., 2008; Kodaira et al., 2010). However, remnants of this older crust have not been found in the Izu collision zone. Tamura et al. (2010) integrated new geochemical results with recent geophysical imaging of the arc and concluded that Miocene plutonic rocks in the Izu collision zone are from the Eocene–Oligocene middle crust, which was partially melted, remobilized, and rejuvenated during the collision. Moreover, (1) the mafic arc lower crust is missing at the collision zone (Kitamura et al., 2003) and (2) the aseismic Philippine Sea plate, which is subducted at depths of 130-140 km without evidence of a tear or other gap, has been detected even beneath areas 120 km NW of the collision zone (Nakajima et al., 2009). These lines of evidence suggest that the down-dragged middle crust would partially melt and coalesce in the upper plate, but the mafic (high in iron and magnesium) lower crust would not melt and subduct into the deep mantle, resulting in delamination and separation of the middle crust from the lower crust. Both processes are inevitable at the collision and are necessary to yield continental crust. Thus, it is suggested that collisional orogeny plays an important role in the genesis of continental crust.

著者

日本地学史編纂委員会 東京地学協会

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.127, no.6, pp.835-860, 2018-12-25 (Released:2019-01-30)

参考文献数

260

---

The development of geomorphology, human geography, history and methodology of geography, regional geography, and geographic education in Japan from 1945 to 1965 are described. Research objectives and methodologies of geomorphology diversified during this period. A series of natural disasters triggered by earthquakes and typhoons raised social demands for disaster prevention and national land-use management. Full-scale geomorphic studies, fused with geology and engineering, started. Historical geomorphology of lowland plains and process geomorphology began to develop, adding to traditional descriptive geomorphology. The Research Institute for Natural Resources and the Geographical Survey Institute contributed to the postwar reconstruction of geomorphology. Aerial photo interpretation and quantitative land surface analyses developed. A hierarchical landform classification for lowland plains was established and applied to many plains in Japan and developing countries, in order to predict areas subject to flooding and land use planning. The postwar education system increased the number of physical geographers. They contributed to the land classification of Japan as a whole and increased interest in Quaternary environmental changes such as climate and sea level changes, as well as crustal movements, which have produced landform diversity. In 1956, they established the Japan Association for Quaternary Research in cooperation with geologists, anthropologists, and archaeologists. Human geographical research in postwar Japan was far more active and diverse than in the prewar years. This was partly the result of an increase in academic posts devoted to human geography in relation to curriculum reforms in secondary and higher education. Initially, settlement geography was a major field of study. Subsequently, historical geography and economic geography were gradually popularized with the establishment of specialized academic societies, which were dedicated to both fields of study. Among the newly emerging fields were urban, social, and cultural geography. The history and methodology of geography were viewed as overarching fields connected to both physical and human geography. Despite ongoing diversification within geographical research, various topics in these fields were addressed by Japanese geographers. This reflected long-lasting debates concerning the disciplinary identity of geography itself. Regional geography and geographic education concerned both physical and human geography. These research fields were invigorated because of the relative importance of geography in Japan's secondary and higher education systems up to the early 1960s.

著者

岩田 貴樹 吉田 圭佑 深畑 幸俊

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.128, no.5, pp.797-811, 2019-10-25 (Released:2019-11-15)

参考文献数

49

被引用文献数

10

---

In order to understand crustal dynamics, including the occurrence of earthquakes and the development of mountain ranges, it is important to estimate the stress state in the Earth's crust from observed data. This paper reviews stress tensor inversion techniques using seismological data. The techniques were originally applied to a dataset of slip orientations taken from focal mechanisms. Subsequently, other techniques, which use P wave first-motion polarities or centroid moment tensor (CMT) solutions, were developed. This paper clarifies the principles and basic hypotheses, on which each technique is built. In the techniques using focal mechanisms and P wave first-motion data, the Wallace–Bott hypothesis that a fault slips in the direction of maximum resolved shear stress plays the principal role; basically, we search for a stress state that satisfies observed data on the basis of the Wallace–Bott hypothesis. On the other hand, the stress inversion technique using CMT data is not based on the Wallace–Bott hypothesis; instead, it is assumed that stress released by earthquakes is proportional to the stress tensor in the region surrounding the hypocenter. The characteristics and advantages of these techniques are also compared from physical and pragmatic viewpoints. It would be valuable to further improve these techniques, as well as to compare their performance using synthetic and actual data to clarify the differences and advantages of their characteristics in more detail.

著者

大村 纂

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.106, no.6, pp.890-893, 1997-12-01

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スイスにある10大学中6大学に地理学教室が存在し, そのすべてが理学部または環境学部に付属しており, 自然地理学と人文地理学はほぼ半々でよい調和を保っている。中でもスイス国立工科大学 (ETH), バーゼル大学, ベルン大学およびチューリッヒ大学 (これをスイスでは通常一国立, 三カントン立大学と総称する) の主要大学では3講座以上の規模で独立した学課を担い, また広域な一般教養の教育に参加している。加えるに, スイスの中・高等学校における教員養成の責任もあずかる。

著者

高畑 直人 尾上 哲治 佐野 有司 磯﨑 行雄

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.128, no.4, pp.667-679, 2019-08-25 (Released:2019-09-20)

参考文献数

27

被引用文献数

5

---

It is important to know the influx of extraterrestrial material on old Earth in order to understand global environmental changes. Helium is suitable for detecting extraterrestrial material in marine sediments, as well as platinum group elements, because there is more helium in extraterrestrial matter than on the Earth's surface. Extraterrestrial material is detected in old sedimentary rocks collected from a Permian/Triassic (P/T) boundary section in the Mino Belt, central Japan, which accumulated in a deep seafloor environment in the ancient Pacific Ocean. Much higher 3He/4He ratios (up to 150 Ra; 1 Ra = the atmospheric ratio) are observed in the samples. These high 3He/4He ratios may infer the existence of extraterrestrial helium carried in fullerenes or interplanetary dust particles. Moreover, the distribution of 3He concentrations indicates a significant increase in the influx of extraterrestrial material before the P/T boundary, which is equivalent to the influx at the Cretaceous/Paleogene boundary, because of the long duration. This increase may have caused global cooling leading to mass extinction.

著者

寿円 晋吾

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.75, no.5, pp.266-281, 1966-10-25 (Released:2009-11-12)

参考文献数

34

被引用文献数

1

著者

目代 邦康

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.121, no.2, pp.367-383, 2012-04-25 (Released:2012-05-29)

参考文献数

99

被引用文献数

1 2

---

IWATA Shuji and KOIZUMI Takeei initiated Japanese geoecology studies in the 1970s. The Colloquium of Cold Region Landform (Kanrei Chikei Danwakai) contributed significantly to Koizumi's studies. Early geoecological studies have been classified into two categories: analysis of landscape structure and research on phytogeography. The former is similar to the general system theory. This concept is a good method for understanding the natural landscape and for resolving regional issues. The latter relates to systematic geography. These studies are mainly conducted in mountain areas. While studies on natural environments in mountain areas have advanced, Japanese geoecological studies seem to have focused on special areas. Furthermore, research trends of Japanese geoecological studies were analyzed by examining competitive funding practices. The results illustrate that there have been three types of study since the 1980s: (1) phytogeographical studies and analysis of the landscape structure in cold regions such as polar and high mountain areas; (2) comprehensive geographical overseas studies; and, (3) problem-solving research on regional issues such as resource management and countermeasures for natural disasters. Currently, phytogeographical studies and problem-solving research are advancing. However, Japanese geoecological studies have not appealed to researchers in different fields until now. The future development of geoecological research requires interdisciplinary research.

著者

荒川 秀俊

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.65, no.1, pp.55-56, 1956-01-30 (Released:2009-11-12)

参考文献数

1

被引用文献数

1 1

著者

神保 小虎

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.1, no.4, pp.165-168, 1889-04-25 (Released:2010-10-13)

著者

日本地学史編纂委員会 東京地学協会

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.127, no.6, pp.835-860, 2018

---

<p> The development of geomorphology, human geography, history and methodology of geography, regional geography, and geographic education in Japan from 1945 to 1965 are described. Research objectives and methodologies of geomorphology diversified during this period. A series of natural disasters triggered by earthquakes and typhoons raised social demands for disaster prevention and national land-use management. Full-scale geomorphic studies, fused with geology and engineering, started. Historical geomorphology of lowland plains and process geomorphology began to develop, adding to traditional descriptive geomorphology. The Research Institute for Natural Resources and the Geographical Survey Institute contributed to the postwar reconstruction of geomorphology. Aerial photo interpretation and quantitative land surface analyses developed. A hierarchical landform classification for lowland plains was established and applied to many plains in Japan and developing countries, in order to predict areas subject to flooding and land use planning. The postwar education system increased the number of physical geographers. They contributed to the land classification of Japan as a whole and increased interest in Quaternary environmental changes such as climate and sea level changes, as well as crustal movements, which have produced landform diversity. In 1956, they established the Japan Association for Quaternary Research in cooperation with geologists, anthropologists, and archaeologists. Human geographical research in postwar Japan was far more active and diverse than in the prewar years. This was partly the result of an increase in academic posts devoted to human geography in relation to curriculum reforms in secondary and higher education. Initially, settlement geography was a major field of study. Subsequently, historical geography and economic geography were gradually popularized with the establishment of specialized academic societies, which were dedicated to both fields of study. Among the newly emerging fields were urban, social, and cultural geography. The history and methodology of geography were viewed as overarching fields connected to both physical and human geography. Despite ongoing diversification within geographical research, various topics in these fields were addressed by Japanese geographers. This reflected long-lasting debates concerning the disciplinary identity of geography itself. Regional geography and geographic education concerned both physical and human geography. These research fields were invigorated because of the relative importance of geography in Japan's secondary and higher education systems up to the early 1960s.</p>

著者

大矢 雅彦

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.84, no.1, pp.46-49, 1975

著者

渡邊 久吉

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.25, no.11, pp.784-786, 1913-11-15 (Released:2010-10-13)

著者

GROSSMAN Michael J. 財城 真寿美 三上 岳彦 MOCK Cary

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.127, no.4, pp.457-470, 2018

被引用文献数

2

---

<p> 歴史文書は,気象官署による測器を用いた公式気象観測が開始される以前の台風復元において,貴重な情報源となる。本稿では,1877年の日本(北海道,本州,四国,九州)に影響をおよぼした台風について,詳細な情報を含む5つの資料(1:日本で出版された英字新聞,2:歴史天候データベース,3:日本の灯台気象観測記録,4:イギリスおよびアメリカ合衆国の船舶の航海日誌,5:中央気象台の気象観測表)の検証を行った。そしてこれらすべての資料から,1877年において日本に上陸もしくは接近した4つの台風事例(6月11日,7月26-27日,8月25-27日,10月11日)が明らかとなり,歴史文書は,日本における暴風雨の位置,移動経路,風速,気圧,被害などに関する詳細な情報を含んでいることが裏づけられた。歴史文書に記録された台風に関する情報は,台風の襲来頻度や強度,挙動に関する理解を,気象観測や台風観測の詳細な数値データが十分に得られない過去の時代にまで,さかのぼる可能性を有しているといえる。</p>

著者

菊地 俊夫

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.120, no.2, pp.433-434, 2011-04-25 (Released:2011-06-30)

著者

小池 拓矢 菊地 俊夫

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.125, no.6, pp.857-870, 2016-12-25 (Released:2017-01-25)

参考文献数

27

被引用文献数

2 6

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The objective of this study is to clarify how the landscape is evaluated by participants of geo-tours on Izu-Oshima Island. The Visitor-employed photography (VEP) method is used to identify places where landscape evaluations are concentrated and objects are photographed frequently. Further, this study discusses the impact of interpretations by tour guides on the landscape evaluations of participants. Izu-Oshima Island, located 120 km south of Tokyo, is a volcanic island which was certified as a geopark in 2010. In this study, university students, who were part of a field excursion, were divided into two groups and accompanied by two tour guides. The results of a Kernel density estimation shows that the locations of photographs taken by the tour participants are concentrated in areas where the tour guides provide interpretations. These locations differ by tour group, which indicates that landscape evaluations are influenced interpretations. Each participant chose five favorite photographs from among their own photographs. Photographs of people were preferred. Tour participants took photographs of geological and geographical features as records; however, photographs of people were preferred as happy memories with friends during the tour. It is important to have both academic and entertaining contents in interpretations during educational activities of Geoparks.

著者

戎崎 俊一

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.127, no.5, pp.577-607, 2018-10-25 (Released:2018-11-14)

参考文献数

122

被引用文献数

2 3

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“Tandem” planet formation, a new theory of planet formation, is described. A steady-state, 1-D model of the accretion disk of a protostar is obtained taking into account magneto-rotational instability (MRI) and porous aggregation of solid particles. The disk is found to be divided into an outer turbulent region, a MRI suppressed region, and an inner turbulent region. The outer turbulent region is fully turbulent because of MRI. However, MRI is suppressed around the midplane of the gas disk, and a quiet area without turbulence appears at rout ( 8-60 AU) from the central star, because the degree of ionization of gas becomes sufficiently low. The disk becomes fully turbulent again at rin ( 0.2-1 AU), because the midplane temperature becomes sufficiently high (> 1000 K). Planetesimals are formed through gravitational instability at both outer and inner MRI fronts. At the outer MRI front, icy particles grow through low-velocity collisions into porous aggregates with low densities (down to ≃ 105 g cm−3). They eventually undergo gravitational instability to form icy planetesimals. Rocky particles, on the other hand, accumulate at the inner MRI front due to the local maximum in gas pressure. They undergo gravitational instability in a sub-disk of pebbles to form rocky planetesimals. They are likely to be volatile-free because of the high temperature (> 1000 K) at this formation site. This is consistent with a model in which the Earth was initially formed as a completely volatile-free planet. Water and other volatile elements came later through the accretion of icy particles with occasional scatterings in the outer regions after solidification of the planet surface. Our new proposed tandem planet formation regime shows that planetesimals are formed at two distinct sites. The former is likely to be the source of outer gas giants and the latter of inner rocky planets. The tandem regime also explains the gap in the distribution of solid components (2-4 AU), and therefore a relatively small Mars and a very small mass in the main asteroid belt. This tandem regime is found not to take place when the vertical magnetic field of the disk is five times weaker than that assumed, because the outer MRI front shifts outward beyond 100 AU. Such a “dispersed planetary formation” regime may explain high eccentricity planets, which are detected in exosolar planetary systems. On the other hand, when the ionization rate due to galactic cosmic-rays is 100 times larger than that of the present value, the outer MRI front shifts down to the inside of the water sublimation zone. Such a “single star formation” regime might explain super Earths or hot Jupiters, because almost all of the rock components in the disk transported to the inner MRI front contribute to planetary formation.

著者

平内 健一 片山 郁夫

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.124, no.3, pp.371-396, 2015-06-25 (Released:2015-07-10)

参考文献数

140

被引用文献数

3 5

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Serpentine minerals (lizardite, chrysotile, and antigorite) are a major group of hydrous phyllosilicates resulting from the hydrothermal alteration of mantle peridotite. Their distinct rheological properties mean that serpentine minerals have a strong influence on the mechanical and seismogenic behavior of faults and plate boundaries in both continental and oceanic settings. In this paper we review the results of laboratory experiments performed to understand the frictional and mechanical properties, and deformation mechanisms of serpentinite. Frictional sliding experiments at low slip rates show that antigorite exhibits velocity-strengthening behavior (a−b > 0) over a wide range of temperature (25-400°C) , while values of (a−b) for chrysotile become negative as temperature increases (25-281°C) . This indicates that the stability of slip along serpentinite-bearing faults depends on the serpentine species and fault depth. Frictional sliding of antigorite at seismic slip rates leads to weakening by flash heating. Axial compression experiments at confining pressures of up to 4 GPa show that antigorite is stronger than lizardite by at least a factor of two. The flow law for dislocation creep of antigorite based on stress values at 〜15% strain also predicts differential stresses that are substantially lower than those for the dislocation creep of olivine at natural strain rates (10−10 to 10−14 s−1) . This suggests that the viscosity of serpentinite promotes slab–mantle decoupling. However, the antigorite flow law should be used with caution because antigorite starts to deform by semi-brittle flow after 〜20% strain. Large-strain simple-shear deformation of antigorite aggregates at high pressure (1 GPa) results in a strong alignment of antigorite c-axes normal to the shear plane. This observation explains the trench-parallel anisotropy beneath the Ryukyu subduction zone. Although dehydration embrittlement is considered a primary cause of intermediate-depth earthquakes, recent high-pressure experiments on antigorite show stable sliding behavior or detect no acoustic emissions during dehydration reactions. We emphasize that the presence of talc derived from the metasomatic alteration of serpentine further weakens and stabilizes the slab–mantle interface and promotes long-lived ( > 1 Ma) detachment faulting.