著者

中林 一樹

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.110, no.6, pp.938-949, 2001-12-25 (Released:2009-11-12)

参考文献数

8

被引用文献数

1

---

In the 21st Century, it has been announced that several earthquakes will occur beneath Tokyo Capital Region. The Tokyo Metropolitan Government implements two kinds of hazard assessments for countermeasures against the earthquake disasters. One is the disaster damage estimation for Tokyo and a disaster scenario for Earthquake that occurres just beneath Cental Tokyo. According to the Report published in 1997, approximately 378, 000 buildings will be burnt down, 43, 000 buildings will be demolished, 7, 200 people will be killed. A disturbance of the water supply will continue for one month and the interruption of piped gas will continue for two months, more than two million people will be evacuated to shelters located mainly in public schools. The other assessment concerns research on the vulnerability of built-up areas against earthquakes measured according to each community area. According to the area vulnerability research, the most vulnerable areas are located as a ring-zone around the CBD and as a finger-zone along Japan Railway's Chuo-line from central Tokyo to the west suburban region (Pictorial 4-1). These zones are made up wooden houses in crowded areas without city planning nor building permission.TMG learned much from the Kobe Earthquake of 1995 and has enlarged earthquake countermeasures to make Tokyo an earthquake-resistant city and to secure effective disaster countermeasures, quick recovery and reconstruction to protest the livelihood of the populace, and to ensure urban redevelopment. The most important measure is the Promotion Plan for Earthquake-resistant City Development Projects, because the implementation of such projects can reduce the damage in Tokyo (Pictorial 4-2). The Preparedness Plan for Urban Reconstruction is one of the new measures that was established after the Kobe Earthquake.

著者

松岡 憲知

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.v-vi, 2012-04-25 (Released:2012-05-29)

参考文献数

3

著者

宮縁 育夫 杉山 真二 佐々木 尚子

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.119, no.1, pp.17-32, 2010-02-15 (Released:2010-05-21)

参考文献数

51

被引用文献数

10 11

---

Holocene environmental changes and vegetation history are constructed using phytolith and macroscopic-charcoal analyses of a 23-m-deep drilling core obtained at the Senchomuta marsh in Asodani Valley, northern part of Aso caldera, SW Japan. An intra-caldera lake existed in the Asodani Valley prior to approximately 9 cal ka (calibrated 14C age). Multiple large flood events occurred during the period 8.9-8.1 cal ka and emplaced thick sandy deposits in the valley basin. Thereafter, the center of the Asodani Valley (northern part of caldera floor) changed to swampy and fluvial environments. sasa (cool-temperature dwarf bamboo) grasslands and/or forests with understory sasa covered slopes of the Asodani Valley basin between 11 and 9 cal ka. sasa phytoliths significantly increased at ca. 7.3-6.5 cal ka, but thereafter decreased. Miscanthus (Japanese pampas grass) grasslands existed continuously on the slopes. Macroscopic-charcoal particles were abundant during the last 6000 years, and the peak (6.1 cal ka) amount of charcoal particles is consistent with that of Miscanthus phytoliths. This indicates that the existence of Miscanthus grassland might be related to fire events. Inside the Asodani Valley, Phragmites (reed) became established continuously along the shore of the intra-caldera lake (prior to ca. 9 cal ka) and in subsequent marshes. Gramineae phytoliths were detected predominately through all horizons of the drilling core, whereas a small amount of arboreal phytolith was observed at most horizons. We, therefore, believe that forests existed on steep slopes such as the caldera wall where human impacts were small, although sasa and Miscanthus grasslands were maintained by human activity outside Aso caldera.

著者

久城 育夫

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.92, no.7, pp.508-515, 1984-01-25 (Released:2009-11-12)

参考文献数

24

著者

黒田 登美雄 小澤 智生

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.105, no.3, pp.328-342, 1996-06-25 (Released:2009-11-12)

参考文献数

29

被引用文献数

9 15

---

Paleoclimatic and vegetational changes during the Pleistocene and Holocene in the Ryukyu Islands were inferred from pollen assemblages. Pollen analyses of some early Pleistocene to Holocene sections in the Ryukyu Islands show several drastic vegetational changes with climatically meaningful variations.A mixed pollen assemblage containing the warm and cool temperate trees such as Cryptomeria, Abies and Tsuga, and the tropical-subtropical trees including Dacrydium, Liquidambar, , Lagerstroemia and Sapium occurred in the upper Pliocene to lower Pleistocene Shinzato Formation and the basal part of the lower Pleistocene Kunigami gravel formation. These pollen assemblages strongly support that there were high mountains over 1, 000 to 1, 500 m above the sea-level in the Ryukyu Islands in the late Pliocene to early Pleistocene. The warm and cool temperate forests in the mountainous areas were disappeared possibly by the subsidence of the basement rocks of the Islands in relation with the opening of the Okinawa Trough. Invasion of evergreen broad-leaved trees to the Ryukyu Islands in the early Pleistocene was indicated by the first occurrence of evergreen broad-leaved tree pollen in the lower Pleistocene Kunigami Gravel Formation.The pollen assemblages in the last Glacial period (ca. 22, 000 y.B.P) are dominated by the coniferous trees such as Pinus and Podocarpus, indicating that an arid climate was prevalent in the Ryukyu Islands. This evidence is consistent with the wide development of ancient dunes and paleosoil of aeolian sand origin in the islands during the last Glacial period. The pollen sequence of the uppermost Pleistocene to Holocene reveals the change of vegetation and climate from the pine forests of the late Glacial period to the climax forests of evergreen broad-leaved trees of the Climatic Optimum. It is suggested that the climatic condition in subtropical Ryukyu Islands around 20, 000 years B.P. was not so much cool but arid than the climate of the present day.

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.1, pp.67-67, 1913-01-15 (Released:2010-12-22)

著者

大森 房吉

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.31, no.1, pp.1-16, 1919-01-15 (Released:2010-10-13)

著者

小元 久仁夫

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.121, no.6, pp.xiv-xiv, 2012-12-25 (Released:2013-01-07)

著者

小元 久仁夫

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.121, no.6, pp.1043-1051, 2012-12-25 (Released:2013-01-07)

参考文献数

36

被引用文献数

4

---

A large number of coral boulders are scattered on reef flats and along the shores of Sakishima Islands, SW of Japan. Many were considered to have been cast ashore by huge tsunamis. In this report the author analyzes the distribution and calibrates the 14C ages of coral boulders collected from Maibahbama, southeast of Miyako Island. The calibrated 14C ages indicate a random distribution; however, some coincided exactly with the 1771 Meiwa tsunami. The tsunami travelled from the epicenter northeast and struck the Higashihenna Promontory, then turned westward leaving a large numbers of coral boulders on Maibahbama. Judging from tsunami deposits overlaying the lowest marine terrace the wave height seems not to have exceeded 10m.

著者

若林 芳樹 伊藤 悟

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.103, no.3, pp.221-232, 1994-06-25 (Released:2009-11-12)

参考文献数

34

被引用文献数

2 6

---

Geographical approach to cognitive maps has mainly focused on measurement of their spatial patterns. Recently Lloyd (1989) devised a useful method for analyzing the components of distortions in cognitive maps by means of Euclidean regression. Until now, however, this method has not yet been validated. The purpose of this study was to reexamine his concepts about the distortions in cognitive maps and to test their validity.We pointed out several discrepancies between the concepts of distortions and their operational definitions given by Lloyd (1989). To overcome this problem, the absolute distortion that appears in the configuration before Euclidean regression ought to be distinguished from the systematic distortion that is measured by the parameters of Euclidean regression. While the systematic distortion that indicates a Euclidean property of the distortion can be explained by alignment and rotation heuristics (Tversky, 1981) and implicit scaling model (Holyoak and Mah, 1982), the relative distortion that remains after Euclidean regression cannot be explained by general theories. In addition, these geometrical components of distortion ought to be distinguished from statistical ones, namely, distortion (central tendency) and fuzziness (dispersion) defined by Gale (1982).On the basis of this conceptualization, we carried out an empirical analysis of the distortion in the cognitive map of Kanazawa City. The data used in this study were obtained by a conditional sketch mapping drawn from 113 students of Kanazawa University. Locations to be answered were 21 transportation nodes within the central part of the city known by more than 90 percent of the students. From these locations, two major landmarks of CBD were selected as reference points. Subjects were asked to indicate the remaining 19 locations on the legal-size sheet in which the two reference points were printed.We detected the absolute distortions, overlaying the cognitive maps for all samples on the actual map so as to fit the locations of two reference points into the actual ones. The patterns of the absolute distortion indicated that the amount of errors increased with distance from the reference points, and that the locations in cognitive maps commonly shifted outward from the actual ones. Specifically, these displaced locations in southern or eastern part of the city indicated a counterclockwise shift, which suggested a directional bias in cognitive maps.In order to separate the systematic distortion from the relative one, each of the cognitive configurations was fitted into the actual map by Euclidean regression. Parameter estimates of the scale change averaged 0.593, which suggested that cognitive maps were enlarged about twice the size of the actual map. Mean direction of the rotated angle amounted to-22.2 degrees, which implied that cognitive maps were rotated counterclockwise about 20 degrees from the actual map so as to coordinate the cardinal directions of the cognitive map with the actual one. This tendency can be due to the displacement of two river channels as major reference lines in Kanazawa from cardinal directions.After eliminating the systematic distortions by Euclidean regression, the actual map was overlaid with all the cognitive maps. The overlaid maps indicated that the local patterns of relative distortions reflected hierarchical structure of cognitive maps (Stevens and Coupe, 1978) although the amount of them was smaller than that of the systematic distortions.

著者

小林 貞一

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.95, no.4, pp.225-240, 1986-08-25 (Released:2009-11-12)

参考文献数

30

被引用文献数

1

---

IV. Research in geology of Manchuria i.e. Northeast China was commenced with RICHTHOFEN's trip in its southern part in 1869. In 1895 AHNERT's life work on the geology of Central and North Manchuria was started, and KOCHIBE carried out a preliminary survey in South Manchuria. Since 1923 geological papers of Manchuria were published by Y. C. SUN and others in Bull. Geol. Soc. China from 1923. Geological survey founded in South Manchurian Railway Company published Geological Map of South Manchuria, 1918 and Geology and Mineral Resources of the region, 1929. There are many papers in the regional geology written by Japanese geologists and palaeontologists.Besides late Permian naiads Silurian-Permian marine fossils were discovered in Central and North Manchuria and the Manmo group was proposed for the whole sequence of the Palaeozoic rocks accumulated in the Mongolian geosyncline. It was strongly disturbed by the Permo-Triassic orogeny accompanied by the Mongolian granite with the result that the area was consolidated and united with South Manchuria. Small basins were later brought about there and the large Liao-Sungari basin was produced in the late Mesozoic age. Recent studies by Chinese geologists reveal that the Manmo group comprises Cambrian and Ordovician fossils in its lower part and that it is rich in volcanic materials of different ages. Permian plants and lower and middle Triassic non-marine animals were discovered at some places. Further it is known that sea entered into the eastern part of Heilongjiang province temporarily in the late Triassic, middle-upper Jurassic and Cretaceous ages.V. PUMPELLY's geological reconnaissance in 1863-65 was the first in China, followed by RICHTHOFEN and others including Japanese geologists. The Tokyo Geographic Society published Geological Maps of South and North China and then of Eastern Asia all in 1 by 2 mills, scale in 1920, 1922 and 1929 respectively.According to E. T. CHANG (1922) mining was started in China already in prehistoric age. Chinese classics on stone medicine and related knowledge were imported to Korea and Japan. Among Chinese geologists CHANG was first to write geology of Chekiang, 1911. The Central Geological Survey at Nanking, Department of Geology in the National University of Peking and the Geological Society of China were successively founded in 1916, 1920 and 1922. Since then her geology advanced considerably except for some years from 1966. The research activity, however, became quite explosive from about 1973. The Geological Map of China in scale of 1/4 mills. was compiled in 1976 by the Chinese Academy of Geological ScienceAn outline of Tectonic characteristics of China and the Tectonic Map of China were published by T. K. HUANG and his cooperators in 1977 and 1979 respectively.Supplementary notes are given on the Pentsao and world map (1) and the growth of Asia documented in the expansion of the non-marine facies in the continent (2).

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.39, no.4, pp.243-245, 1927-04-15 (Released:2010-12-22)

著者

齋藤 半六

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.7, pp.300-312, 1939-07-15 (Released:2010-10-13)

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.10, no.9, pp.519-520, 1898-09-15 (Released:2010-12-22)

著者

堤 浩之 Andrei I. KOZHURIN Mihail I. STREUTSOV 植木 岳雪 鈴木 康弘 渡辺 満久

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.109, no.2, pp.294-301, 2000-04-25 (Released:2010-11-18)

参考文献数

10

被引用文献数

3 6

---

We have mapped a series of north-trending faults along the northeastern coast of Sakhalin, Russia, based on aerial photograph interpretation and field observations. These faults include the Upper Pil'tun fault which ruptured during the 1995, Mw 7.0 Neftegorsk earthquake, and the Ekhabi-Pil'tun and Garomay faults east of the surface ruptures. The coseismic displacement associated with the 1995 earthquake shows that the Upper Pil'tun fault is a right-lateral strike-slip fault. Right-lateral stream offsets as much as 80m demonstrate that similar earthquakes have occurred repeatedly along the fault in the late Quaternary. The fault extends for 10 km further to the south beyond the southern termination of the 1995 surface breaks, which is consistent with the coseismic ground deformation detected by SAR interferometry. The Ekhabi-Pil'tun fault trends N10° W to N10°E with a series of fault scarps down-to-the-west across low-relief hilly terrain eroded byperiglacial processes. Right-laterally offset streams and lake shores suggest thatthe Ekhabi-Pil'tun fault is also a right-lateral strike-slip fault. A 3-m-deep trench across the fault north of the Sabo River contains geologic evidence of two episodes of pre -historic surface faulting. The most recent event occurred after 4000 yr B.P. and the penultimate earthquake occurred at about 6200 yr B.P. The interval between the events is greater than 2000 years, which is significantly longer than that obtained for the Upper Pil'tunfault by previous trench excavations.

著者

亀田 純 木村 学 O. A. MELINIKOV 早坂 康隆 橋本 善孝 坂島 隆彦 新井 孝志 芳野 極 鈴木 紀毅

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.109, no.2, pp.235-248, 2000-04-25 (Released:2010-11-18)

参考文献数

21

被引用文献数

4 7

---

The region from Sakhalin in Russia to the eastern margin of the Japan Sea has been regarded as a convergent plate boundary zone between the Eurasia and the North America Plates because large earthquakes and active crustal movements are prominent in this zone. These activities along the eastern margin of the Japan Sea to southern Sakhalin are almost consistent with the expected relative plate motion deduced from the Euler pole which is estimated from the magnetic anomaly lineations in the Atlantic Ocean, but the modern tectonic aspect in northern Sakhalin is inconsistent; e.g., 1995 Neftegorsk Earthquake is one of the typical events.As a result of a structural and tectonic study in northern Sakhalin, the NE-SW compressive tectonic feature since the Late Miocene was clarified. In the northernmost area of the Schmidt Peninsula, the early Cretaceous ophiolite thrusts upon the Late Cretaceous sedimentary rocks. The ophiolite has an overturned sequence: serpentinites, gabbros, basaltic rocks, and hemipelagic sediments in descending order. The Cretaceous sediments form a map-scale and NW vergent synclinorium. All the deformation structures in outcrop scale, such as micro-folds, minor reverse and normal faults, axial plane cleavages and bedding slips, are consistent with a large scale folding. These structural relationships suggest only one event of deformation, which appears to be linked to overthrusting of the ophiolitic rocks.A structural investigation of the southeastern part of the Schmidt Peninsula revealed that the Middle Miocene sediments composed of siltstone and sandstone are folded with wavelength of several tens to several hundred meters. Their fold axes trend in the NW direction, which indicates that deformation under the NE compression is the same as the deformation in the northernmost area. The thickness of sedimentary layers are constant everywhere in folding. This fact indicates that the timing of the deformation is after sedimentation, that is, after the Middle Miocene. This deformation event is consistent with modern activity in northern Sakhalin. Therefore, the modern tectonic framework might have started in the Late Miocene time.A plate tectonic model indicates that the modern relative motion between the Eurasia and the North America Plate started at about 11 m. y. ago. The Late Miocene onset of the modern tectonic framework in northern Sakhalin occurred at almost the same time. The most reliable model to explain the discrepancy of sense of movement from the Eurasia-North America retative motion, may be the “extrusion” of the Okhotsk Block toward the Pacific Ocean. The dextral extrusion boundary in northern Sakhalin may be traced along theeastern coast of Sakhalin to the northern edge of the Kuril Basin, where active seismicityhas been observed although a detailed study of focal mechanisms and other tectonic aspects is needed in the future.

著者

磯部 清

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.72, no.5, pp.244-256, 1963-10-30 (Released:2009-11-12)

参考文献数

17

著者

吉田 明夫 伊藤 秀美 細野 耕司

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.105, no.1, pp.77-87, 1996-02-25 (Released:2009-11-12)

参考文献数

22

被引用文献数

2 2

---

Several examples are presented which seismic quiescence appeared in a wide area around the foci of intraplate earthquakes before their occurrence. A noteworthy feature is that the quiescence area extends along tectonic zones over more than several times of the focal region of the main shock. This phenomenon suggests that stress in a wide area along tectonic zones changes before the occurrence of major intraplate earthquake. We consider that the stress change is a manifestation of a significant physical process leading to earthquake occurrence. An apparently puzzling fact which earthquake precursors are sometimes observed at distant places from the focal region in the specific direction may be explained by such stress change. Further, it is expected that the precursory seismic quiescence provides us with a promising clue to the short-term prediction of intraplate earthquake.

著者

森 慎一 藤岡 換太郎 有馬 眞

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.4, pp.585-614, 2010-08-25 (Released:2010-11-08)

参考文献数

89

被引用文献数

2 6

---

This paper describes topographic and geologic features of the northern part of the Sagami Trough and surrounding areas, off central Japan, and discusses the role of the Philippine Sea plate in the development of the trough's topography and fault systems. In the study area, the Okinoyama Bank Chain, Miura Basin Chain, and several spurs are aligned NW-SE parallel to the axis of the Sagami Trough. We examine the lithological compositions of rock and piston-core samples collected from the R/V Hyper Dolphin during Japan Agency for Marine-Earth Science and Technology dives 906 and 907, and rock samples dredged during Ocean Research Institute of the University of Tokyo cruise KT88. These samples represent mainly volcaniclastic rocks derived from the volcanoes of the Izu arc and subordinate amounts of terrigenous sediment interpreted as derived from the Sagami and Sakawa Rivers. The topographic and geologic data define five fault systems in the eastern part of the northern Sagami Trough. We interpret the Okinoyama Bank Chain as an elevated outer-ridge belt developed at the landward slope of the plate boundary, which is represented by NW-SE trending right-lateral reverse faults (F1). At the northeast side of the Okinoyama Bank Chain, NW-SE trending normal faults (F2) formed and the Miura Basin Chain developed. The cutting relationship between these fault sets suggests that the collision of the Izu arc with the Honshu arc imposed a right-lateral shear stress field on the Okinoyama Bank and Miura Basin Chains. This shear stress may have led to clockwise rotation of these tectonic blocks formation of a set of NE-SW trending left-lateral reverse faults (F3). The initiation of the Izu block collision is interpreted as a turning point after which the northward motion of the Philippine Sea plate abruptly changed to NW and the Sagami Bay area came under a NW-SE compressional stress field, which resulted in the development of E-W trending right-lateral faults (F4) in the narrow shelf off the Miura Peninsula. A number of spurs subsequently developed along these faults. Finally, NNE-SSW trending right-lateral normal faults (F5) developed under an E-W extensional stress field, which caused the formation of N-S trending topographic depressions such as Tokyo Canyon and submarine highs such as Okinoyama and Oiso Spur.

著者

本郷 宙軌

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.5, pp.860-871, 2010-10-25 (Released:2011-01-21)

参考文献数

23

被引用文献数

1 2

---

Coral reef terraces are one of the best recorders of biological response to environmental change events (e.g., sea-level changes). Kikai Island provides a rare opportunity to show biological and ecological frameworks (e.g., competition, coexistence, and succession) during a recent geological period. The island is fringed by raised Holocene raised reef terraces, which formed as a result of periodic tectonic uplifts. This study aims to characterize the spatial and temporal changes of corals at this island during the Holocene. The analysis is based on topographical and biological data obtained for the three sites (Shidooke, Kadon, and Nakugama reefs). Three raised reef terraces (Terrace II, III, and IV) grew from 7300 to 4500 years ago (during 2800 years), from 4500 to 2900 years ago (during 1600 years), and from 2900 to 1800 years ago (during 1100 years), respectively. Terrace II and III were uplifted 1-2 m around 4500 years ago and around 2900 years ago. Terrace IV was uplifted 1-2 m around 1800 years ago. The modern reef has been composed of corals for 1800 years. Sixteen coral genera and 53 species were recorded from the reef terraces. Terrace III and IV were dominated by four coral species (A. digitifera, A. robusta, G. retiformis, and F. stelligera), but Terrace II was predominantly composed of A. digitifera and A. robusta. These biological and ecological variations between the terraces represent a growth strategy responding to differences of reef growth time and/or insolation.