著者

丸山 茂徳 磯崎 行雄 柳井 修一 下司 信夫 佐野 修 笠原 順三

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.119, no.6, pp.959-962, 2010-12-25 (Released:2011-03-17)

参考文献数

28

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.37, no.12, pp.725-726, 1925-12-15 (Released:2010-12-22)

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.120, no.5, pp.803-818, 2011-10-25 (Released:2012-01-17)

参考文献数

126

被引用文献数

3 5

---

Geoconservation for geographical and geological phenomena is the most important concept associated with a geopark scheme. However, there is not enough discussion on geopark activities in Japan. Japanese Earth scientists have acted individually to conserve the natural environment, but large-scale conservation projects have not been carried out as activities of research organizations of academic societies. One of the contributions the Earth sciences have made to society is to report the scientific value of regional natural environments. Japanese Earth scientists should make detailed inventories of landforms, strata, and soil and evaluate them. Earth scientists will be able to contribute to conserving nature and sustainable development of regions through these activities. The RIGS system of the United Kingdom is a good model.

著者

苅谷 愛彦 松永 祐 宮澤 洋介 小森 次郎 石井 正樹 佐藤 剛

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.117, no.5, pp.870-877, 2008-10-25 (Released:2010-04-27)

参考文献数

12

被引用文献数

1

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The Daisekkei Valley (1600-2300 m ASL) is a late Pleistocene glaciated trough in the northern Japanese Alps, and its attractive landscape has enchanted many climbers. Even today, there is a late-lying snowpatch 2 km long at the bottom of the valley in midsummer. Unique natural conditions in and around the Daisekkei Valley (e.g., Quaternary rapid uplift, complex geology, humid climates, sparse vegetation cover) have been responsible for the occurrence of various geomorphic changes that threaten climbers. This study, using an image data-logger capable of capturing a JPG image with a fixed time-interval in the summer of 2007 reveals supranival debris movements, micro-weather conditions and the behavior of climbers in the Daisekkei Valley. Analysis of captured images indicates that the daily numbers of dangerous supranival debris movements gradually decreased from early June to early August and supranival debris movements were caused by rock fragments moving in from valley walls or tributaries to the snowpatch, as well as posture changes of rock fragments on the snow surface with rapid ablation. Besides, image-inspection allows us to consider the relationships among climber traffic, micro-weather, and holiday almanac. Using an image data-logger for monitoring geomorphic changes is considered to be effective for analyzing alpine environments.

著者

飯本 信之

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.51, no.6, pp.278-286, 1939-06-15 (Released:2010-10-13)

著者

青木 一勝 大藤 茂 柳井 修一 丸山 茂徳

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.313-332, 2010-04-25

被引用文献数

10 24

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The Sanbagawa metamorphic belt in SW Japan was previously considered to extend in the E-W direction from the Kanto Mountains to Kyushu Island, a distance > 800 km. However, Aoki <i>et al.</i> (2007) recently demonstrated that protoliths of metamorphic rocks in the Oboke area of the belt in central Shikoku accumulated at the trench after <i>ca.</i> 90-80 Ma. Furthermore, Aoki <i>et al.</i> (2008) showed that these rocks suffered blueschist metamorphism at 66-61 Ma, which differs from the timing of the Sanbagawa metamorphism. Thus, these results show that the Sanbagawa belt in Shikoku is a composite metamorphic belt. We, therefore, redefine the traditional Sanbagawa belt; the structurally upper part is the Sanbagawa metamorphic belt (<i>sensu stricto</i>). It formed as an accretionary complex at <i>ca.</i> 140-130 Ma and subsequently experienced BS-EC facies metamorphism at <i>ca.</i> 120-110 Ma (Okamoto <i>et al.</i>, 2004). By contrast, the structurally lower segment termed the Shimanto BS facies metamorphic belt, formed as an accretionary complex after <i>ca.</i> 90-80 Ma and experienced peak metamorphism at <i>ca.</i> 60 Ma. Our observations have important implications for the lateral extension of these two metamorphic belts in SW Japan. The accretionary ages of the traditional Sanbagawa belt in the Kanto Mountains are younger than the Sanbagawa peak metamorphic age (Tsutsumi <i>et al.</i>, 2009), clearly indicating that the entire region of Kanto Mountains Sanbagawa must belong to the Shimanto metamorphic belt. The same timing relationships were also found for the Sanbagawa belt on Kii Peninsula (Otoh <i>et al.</i>, 2010). These results, therefore, indicate that the Shimanto metamorphic belt is exposed in Shikoku, Kii, and Kanto, thus the spatial distribution of Sanbagawa belt (<i>ss</i>) is less than half of its previous extent. The metamorphic grade of the Kanto Mountains in the Shimanto metamorphic belt ranges from pumpellyite-actinolite facies to epidote-amphibolite facies. Therefore, the higher-grade rocks of the Shimanto metamorphic rocks are exposed in the Kanto Mountains in comparison with Shikoku and Kii Peninsula. Hence, these two distinct BS-EA-EC (?) metamorphic belts are virtually equivalent in terms of spatial distribution, metamorphic range of grade, and facies series. Pacific-type orogenic belts typically comprise accretionary complex, high-P/T metamorphic belt, fore-arc sediments, and batholith belt landward from the trench (Maruyama <i>et al.</i>, 1996). In SW Japan, the Sanbagawa belt (<i>ss</i>) is paired with the Ryoke low-P/T metamorphic belt and with the <i>ca.</i> 120-70 Ma Sanyo TTG batholith belt. Furthermore the related fore-arc basin may have developed penecontemporaneously with the Shimanto BS-EA orogeny, which is paired with the late Cretaceous to early Tertiary San-in TTG belt, which extending along the Japan Sea coast. In-between the intervening Izumi Group, a fore-arc basin deposit formed during the Campanian to Maastrichtian. Thus, these two groups of orogenic units, which formed during independent orogenies were both extensively modified during the opening of the Japan Sea <i>ca.</i> 20 Ma. The southward thrusting of the Ryoke and Cretaceous TTG belts over the Sanbagawa extended beyond the southern limit of the Sanbagawa, leading the up-down relationship of the Sanbagawa (<i>ss</i>) and the Ryoke belts.

著者

入倉 孝次郎 三宅 弘恵

出版者

学術雑誌目次速報データベース由来

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.110, no.6, pp.849-875, 2001

被引用文献数

25 92

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We propose a recipe to predict strong ground motions from scenario earthquakes which are caused by active faults. From recent developments in waveform inversion analysis for estimating rupture processes during large earthquakes, we have understood that strong ground motion is relevant to slip heterogeneity rather than total moment on the fault plane. The source model is characterized by three kinds of parameters, which we call : outer fault parameters, inner fault parameters, and extra parameters. The outer fault parameters are parameters characterizing the entire source area such as total fault length, fault width, and seismic moment. The total fault length (L) is related to the grouping of active faults, <I>i.e.</I> the sum of the fault segments. The fault width (W) is related to the thickness of the seismogenic zones. The total fault area S (=LW) follows the self-similar scaling relation with the seismic moment (M<SUB>0</SUB>) for moderate-size crustal earthquakes and departs from the self-similar model for very large crustal earthquakes. The locations of the fault segments are estimated from the geological and geomorphological surveys of the active faults and/or the monitoring of seismic activity. The inner fault parameters are parameters characterizing fault heterogeneity inside the fault area. Asperities are defined as regions that exhibit large slip relative to the average slip on the fault area. The relationship between combined area of asperities and seismic moment M<SUB>0</SUB> satisfies the self-similar scaling relation. The number of asperities is related to segmentation of active faults. The rake angles of slips on the asperities should be estimated from the geological survey and/or geodetic measurements. The extra fault parameters are related to the propagation pattern of rupture within the source area. Rupture nucleation and termination are related to the geometrical patterns of the active-fault segments. The recipe proposed here is to construct the procedure for characterizing those inner, outer, and extra parameters for scenario earthquakes. Then, we have confirmed that the scaling relations for the inner fault parameters as well as the outer fault parameters are valid for characterizing earthquake sources and calculating ground motions from recent large earthquakes, such as the 1995 Kobe (Japan) earthquake, the 1999 Kocaeli (Turkey) earthquake, and the 1999 Chi-Chi (Taiwan) earthquake. We have also examined the recipe for estimating strong ground motion during the 1948 Fukui (Japan) earthquake. The simulated ground motions clearly explain the damage distribution in the Fukui basin.

著者

中田 高 蓬田 清 尾高 潤一郎 坂本 晃章 朝日 克彦 千田 昇

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.104, no.1, pp.127-142, 1995

被引用文献数

30 48

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Distinctive ruptures of the surface faulting which generated the destructive 1995 Hyogoken-Nanbu Earthquake (M<SUB>s</SUB>=7.2) appeared along the Nojima fault, an active fault on the northwestern coast of Awaji island, Japan. The surface fault ruptures in Awaji island extend southwestward continuously for about 9km from Easki near the epicenter to Toshima in Hokudan town, and caused prominent right-latearl off-sets of 1.9m at maximum on roads, paddy dikes with vertical displacement of 1.2m at maximum, while no large surface faulting has been reported in Kobe where major damage and casualties have appeared.<BR>Most of the surface ruptures follow along the pre-existing active fault traces of the Nojima fault. The ruptures are generally arranged in left-stepping echelon, and local extensional and compressional jog forms such as trenches, mole tracks, buldges are sometimes related to changes in fault strikes.<BR>The earthquake fault seems to have propagated bilaterally northeastward and southwestward from the hypocenter in the Straits of Akashi near the major jog of the earthquake fault system. The source process of the earthquake deduced from the slip distribution along the earthquake fault in Awaji island well explains near-field P-waveforms of broad-band seismometers for early part in about 4 seconds. The later part of much larger amplitude should attribute to the northeast fault ruptures toward Kobe.

著者

小森 次郎 ツェリン プンツォ

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.119, no.3, pp.iii, 2010-06-25 (Released:2010-08-30)

参考文献数

1

被引用文献数

1 1

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2009年4月29日,ブータン中部を南流するPho Chhu(Chhuは川の意味)右岸のTshojo(チョゾ)氷河から融氷水の急激な流出(以下では「異常出水」とする)が発生した.これによる被害は特に無かったが,氷河末端から70km下流の町トンサでは1994年に別の氷河からの氷河湖決壊洪水を経験しており,今回の異常出水でも住民が避難する騒ぎとなった.ここでは現地の写真と衛星画像をもとに概略を紹介する.

著者

青山 千春 松本 良

出版者

Tokyo Geographical Society

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.118, no.1, pp.156-174, 2009-03-25

参考文献数

28

被引用文献数

6 15

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During methane hydrate exploration and research, remote and on-board acoustic surveying and monitoring of methane hydrate can be easily and economically conducted using a quantitative echo sounder. Simultaneously, the structure and the floating-up speed of methane plumes can be obtained from an analysis of acoustic data.<br> We conducted a survey of methane plumes from 2004 through 2008 at a spur situated southwest off the coast of Sado Island (tentatively called Umitaka Spur) and at the Joetsu Knoll. In 2007 and 2008, we performed experiments by releasing methane hydrate bubbles and methane hydrate, and letting them float upward. Consequently, we demonstrated that acoustical reflection from the methane plumes correlates with water temperature and depth, that the floating-up speed is constant but depends on the conditions of methane hydrate, that the discharge of methane hydrate bubbles changes, and that there is a wide scattering of materials below the seafloor where methane plumes are located. Furthermore, the amount of methane hydrate bubbles seeping was estimated by a preliminary calculation.<br> The method will be applied not only to basic research on methane hydrate but also to assessments of the environmental impact of methane hydrate exploitation.

著者

下條 将徳 大藤 茂 柳井 修一 平田 岳史 丸山 茂徳

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.119, no.2, pp.257-269, 2010-04-25 (Released:2010-07-06)

参考文献数

32

被引用文献数

32 43

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The Japanese Islands have grown through the formation of igneous rocks and accretionary prism caused by subduction of oceanic plates. However, the timing of the initiation of the subduction is not well defined. The South Kitakami Belt (SKB) in NE Japan is the best field to solve this problem. Here, basement igneous rocks are covered by successions of Ordovician to Early Cretaceous beds (450-100 Ma). We obtained LA-ICP-MS U-Pb zircon ages from the following localities. Along the Yakushigawa-Valley section in the northeastern part of the SKB, we examined the ages of (1) trondhjemite of the Kagura Complex of basement igneous rocks, (2) felsic tuff of the Koguro Formation conformably covering the Kagura Complex, and (3) Yakushigawa Formation covering the Koguro Formation and lying under the Silurian Odagoe Formation. In the Ohasama area in the northwestern part of the SKB, we examined the age of (4) Nameirizawa Formation, which probably lies below the Silurian Orikabetoge Formation. Moreover, we examined the ages of four samples from the Hikami Granite body in the central part of the SKB. The ages of trondhjemite (08331-5: 466±6 Ma) of the Kagura Complex and felsic tuff (08331-4b: 457±10 Ma) of the Koguro Formation indicate that the subduction of an oceanic plate had already started at 466 Ma, and that the Koguro Formation is the oldest age-known formation of the SKB. The tuffaceous sandstone of the Yakushigawa Formation (08331-3) has detrital zircons with the youngest age cluster of around 425 Ma, and is probably a Silurian formation. The tuffaceous sandstone of the Nameirizawa Formation (08331-9) has detrital zircons with the youngest age cluster of around 430 Ma. The formation is probably a Silurian formation and is correlated with the Yakushigawa Formation. Precise ages of around 412 Ma were obtained from the Hikamiyama body of the Hikami Granitic Rocks (08330-1,-3,-4), clearly suggesting that at least some parts of the body are not pre-Silurian basement.

著者

奥貫 圭一

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.117, no.2, pp.324-340, 2008-04-25 (Released:2010-06-02)

参考文献数

48

被引用文献数

3 2 2

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This paper discusses spatial analysis and applicable tools available in GIS environments. Since the 1990s, organizations conducting research in the field of Geographic Information Science (GISci) have been developing software packages and extension toolboxes for spatial analysis. Many researchers dealing with spatial phenomena have little knowledge of the wide selection of GISci applications that can be applied to spatial analysis in their research. They can benefit from information and direction on valuable computational resources that can be applied to their specific research problems. FreeSAT, an online portal, has been constructed to provide researchers with information on spatial analysis tools. The FreeSAT website provides links to a wide variety of spatial analysis tools and information on specific research problems to which these tools can be applied. This paper also discusses various computational methods for spatial analysis, such as the nearest neighbor distance, K-function, Voronoi's tessellation, and Huff-based marketing methods, which are all found at the FreeSAT site. It also provides detailed discussions on the application of Spatial Data Analysis Machine (SDAM) and Spatial Analysis on a NETwork (SANET) toolboxes to spatial analysis. While most toolboxes of this type are developed by organizations in the United States or Europe, both SDAM and SANET were developed by organizations in Japan.

著者

大河原 正文 塚脇 真二

出版者

学術雑誌目次速報データベース由来

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.111, no.3, pp.341-359, 2002

被引用文献数

5 8

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東南アジア最大の湖であるトンレサップ湖は雨季と乾季とでその水深・冠水面積が大きく変化し, このような季節的変動に支配された特異な堆積作用の発生が予期される。そこで同湖における堆積作用の解明へ向けて, 同湖に堆積物を供給する関連水系や同湖周辺に分布する沖積層の堆積物の粘土鉱物組成にもとづき, 同湖北部湖底堆積物に含まれる粘土鉱物の起源およびその時間的変化を調べた。<BR>トンレサップ湖北部の表層堆積物ならびに懸濁物からは, カオリン鉱物, イライト, スメクタイトおよび緑泥石が検出される。同湖とメコン河とを連絡するトンレサップ川の堆積物からもイライトおよび緑泥石が検出されるにもかかわらず, 同湖北部周辺の水系や沖積層の堆積物にこれらがほとんど含まれないことから, 同湖北部に分布するイライトおよび緑泥石はメコン河本流を起源とするものと判断される。<BR>一方, トンレサップ湖北部湖底から採集された柱状試料では, その上部約50cmの堆積物からはイライトならびに微量の緑泥石が検出されるものの, 同試料下部にはこれがまったく認められない。したがって, イライトおよび緑泥石がメコン河水系に由来するという表層堆積物解析結果にもとづき, 同湖における堆積物の供給源に大きな変化が発生したことが推定され, その年代は今から約5,000年前と考えられる。

著者

市來 雅啓 茂出木 理子 中村 恭之 柴尾 美紀子

出版者

Tokyo Geographical Society

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.109, no.6, pp.993-1005, 2000-12-01

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The comprehensive Earth science database, GeoRef, is introduced in this paper. GeoRef is one of the Earth science databases with the largest number of references (about 2.2 million), and is managed by American Geological Institute (AGI). GeoRef provides not only an environment for searching references, but also for delivering the necessary references and for making written reference lists.<BR>To verify the usefulness of GeoRef, we compared several cases of searches using GeoRef, Web of Science and Swet Scan. Although GeoRef was not able to pick up more references than Web of Science, GeoRef generally collected suitable references and showed its usefulness of searching particularly in the geological category. However, it was revealed that GeoRef was relatively slow to incorporate the latest information.

著者

高阪 宏行 関根 智子

出版者

Tokyo Geographical Society

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.117, no.2, pp.455-463, 2008-04-25

被引用文献数

1 2

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The aim of this paper is to review the present situation of business Geographic Information Systems (GIS) in Japan. This paper especially focuses on various geographic information services produced by geographic information technology. Geographic information is defined as attribute data with location and geographic information technology is considered in the second section in terms of software and hardware for manipulating geographic information. The third section reviews location-based services (LBS), which trace positions in real-time using location sensor technology. LBS are classified into six types of service: provision of information specified for a position, tracing service for people, tracing service for vehicles and ships, tracing service for luggage and goods, proximity-based notification, and proximity-based actuation. Spatial analysis on GIS has been applied in business tools to assist sales promotion activities and the posting of handbills in shops and offices. The fourth section presents trade area analysis used to perform effective sales promotion activities. Rating methods and spatial interaction models are also used for location assessments of sites proposed for new shops. The fifth section considers geodemographics as an area marketing tool. The last section presents the outlook for business GIS in Japan.