著者
中田 高 堤 浩之 PUNONGBAYAN Raymundo S. RIMANDO Rolly E DALIGDIG Jessie DAAG Arturo
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.99, no.5, pp.515-532, 1990
被引用文献数
5 9

The Philippine Earthquake (Ms=7.8) broke out in July 16, 1990 along the Philippine Fault in Central Luzon. The Philippine Fault is seismically very active and large earthquakes of M 7 class have occurred during this century along this fault. However large earthquakes have not taken place along the active traces of the fault in the Central Luzon during this century, while two large historical earthquakes occurred along its southern trace in 1645 and its northern trace in 1796. Therefore it is considered that the 1990 earthquake was caused by the surface faulting in the seismic (aseismic) gap along the Philippine Fault.<BR>The total length of the surface fault is over 120 km and the fault is divided into two segments by the major bend near Rizal. The surface fault is rather straight and linear and general orientation of the northern segment is N 25 W and the southern segment N40W. Left-lateral displacement is dominant along most of the fault traces and the maximum horizontal displacement is about 6 m in the 60-km-long northern segment and the maximum vertical displacement is 2.0 min the 50-km-long southern section. Sense of vertical displacement changes in places and is consistent with the sense of the displacement along the pre-existing active fault traces. Average displacement along the northern segment is 5-6 m, while 2-3 m along the southern segment.<BR>Along most of the surface fault, ruptures appear exactly along the pre-existing active fault traces. Offsets of roads, foot-pass, streams are common earthquake-induced features. Local extensional and compressional jog forms related to slight change in fault strike creates characteristic features such as depressions, trenches, mole tracks, bulges etc.<BR>The rupture propagated bilaterally northward and southward from hypocenter east of Bongabon near the major bend. The source process of the earthquake deduced from the slip distribution along the surface fault from the epicenter well coincides with that deduced seismologically from the source time function.
著者
尾留川 正平 山本 正三 佐々木 博 金藤 泰伸 朝野 洋一 高橋 伸夫 斎藤 功
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.76, no.5, pp.229-256, 1967-10-25 (Released:2009-11-12)
参考文献数
20
被引用文献数
3

Suburbanization is very phenomenal in the western suburbs of Tokyo, nevertheless a. sizable area is still devoted to agriculture and the agricultural output is quite large. The aim of this research is to survey the ecological aspects of human occupance of the land which is well characterized by the ever intensive urban as well as agricultural use and also to analyze operational structure of farm households that has strongly led the study area to such a suburbanized occupance pattern in terms of interviews of farmers and various statistical materials.Results : 1) Sale of agricultural land is quite limited because of rise of land price, resulting in the juxtaposition of built-up areas and farmlands. 2) Agriculture in these mostly built-up areas has the following characteristics : a) to increase labor productivity rather than land productivity, b) to increase household or personal income whether by specialization on arboriculture, lawn growing, specialized vegetable growing and chicken and pig raising, or by incorporating them in agricultural management so as to improve total agricultural productivity, or from other sources than farming such as management of filling stations, driving, schools, and public baths, and also as white color, c) to hold agricultural land as assets probably for a relatively long period, since the farmers here can get stable income from rent and apartment houses they have built recently, although increment of so-called socially fallow lands is to be seen frequently, and d) to ship out vegetables and eggs to nearby markets or to sell them directly at farmsteads. 3) It is urgently needed to conserve as much farmland as possible and also even to encourage farm management to a degree that the farmers are able to compete with ever-developing urban industries, otherwise the critical shortage of green open spaces in the metropolitanized regions will be further accelerated.
著者
吉川 虎雄
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.72, no.1, pp.8-24, 1963-01-30 (Released:2009-11-12)
参考文献数
10

In February, 1957, the Japanese Antarctic Research Expedition established a station, called “Syowa”, on a small island off Prince Olav Coast, East Antarctica. The station had been occupied by the wintering teams untill February, 1962, except during the period from February, 1958, to January, 1959. Various kinds of scientific observations, for example, aeronomy, meteorology, geology, geomorphology, glaciology, biology, and so on, had been carried out at the station and on its surrounding Antarctic continent. The station was temporarily closed in February, 1962, on account of logistic and financial difficulties, and the reopenning of the station for scientific activities is now being discussed by the Japanese government.In this paper, activities of the Japanese Antarctic Research.Expedition are described and some of scientific results in geography, geology, geodesy, glaciology, and so on are briefly explained.
著者
佐藤
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.21, no.12, pp.847a-848, 1909
著者
ベンター ヤコブ
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.103, no.1, pp.1-15, 1994-02-25 (Released:2010-10-13)
参考文献数
22
著者
吉井 敏尅
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.102, no.4, pp.393-398, 1993-08-25 (Released:2010-11-18)
参考文献数
18
被引用文献数
1 1
著者
菅原 正巳
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.94, no.4, pp.209-221, 1985-08-25 (Released:2010-12-22)
被引用文献数
3 2

The tank model is very simple as shown in Fig. 1. We can consider that it corresponds to the zonal structure of groundwater as shown in Fig. 2. In spite of its simple outlook, the behaviour of the tank model is not so simple. Corresponding to various types of input rainfall, it shows various types of response as shown in Fig. 5 by its nonlinear structure caused by the positions of side outlets which are set somewhat higher than the level of the bottom.The tank model shown in Fig. 1 is used to calculate the daily discharge from the daily precipitation for Japanese river basins. For the flood analysis, data of short time unit are necessary and an appropriate time unit is suggested to be given asT.U.=0.05√A, where T.U. is the time unit (hour) and A is the catchment area (km2). Table 1 shows some examples of appropriate time unit for various catchment areas. For the flood analysis the tank model with two tanks shown in Fig. 6 is applicable.In Japan, the tank model without soil moisture structure can give fairly good results because it is always very humid in Japan. However, for most river basins, the tank model with soil moisture structure shown in Fig. 7 must be applied. The assumed soil moisture structure is composed of two parts, the primary and the secondary soil moisture storages. When the primary soil moisture storage is not saturated, the water is absorbed from the lower tank and there is water transfer between the primary and the secondary soil moisture storages. These two kinds of water transfer are given as shown in Fig. 7c.In regions with long dry season, there is no tree on mountain area or trees have no leave in dry season and vegitation covering can be found on plains or along rivers. In such regions, mountain areas become dry during the dry season, because water moves to lower part of the basin by gravitation. To simulate such a basin, the basin is divided into zones each of which is simulated by the tank model. The tank model of 4X4 type shown in Fig. 8 is derived under such a consideration. During the dry season, zones become dry from mountain side and no evapotranspiration occurs in dry zones. In this model real evapotranspiration from the basin decreases with time corresponding to the dry condition of zones, i.e. areal real evapotranspiration of the basin decreases automatically.The tank model is considered as a black box model without physical meaning by most hydrologists. However, we can ask ourselves, if it is a mere black box, how can such a simple tank model successfully simulate river discharge from high flood to low base flow? There must be some physical meaning in the tank model. Very recently, we were able to find the phenomenon to prove the existence of two kinds of water storage corresponding to the top and the second tank of the tank model by analysing the record of crustal tilt meters affected by rainfall (Fig. 9). The crust is some sort of spring balance which weighs' and so measures the groundwater storage (Fig. 10).
著者
佐渡 耕一郎 亀尾 浩司 小西 健二 結城 智也 辻 喜弘
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.101, no.2, pp.127-132, 1992-04-25 (Released:2010-10-13)
参考文献数
20
被引用文献数
8 5

Three nannofossil datum planes of the Early Pleistocen e are identified in the cores from subsurface at Irabu Island, South Ryukyus. The result allows for the first time to date the initial sedimentation of the reef-related Riukiu Limestone there. It represents the age (1.2M a) turning from siliciclastics to shallow-water carbonate regime. Implication of this transition time is discussed briefly in relation with both local neotectonis m resulting in the birth of a backarc basin (Okinawa Trough) and regional to global reor ganization of paleoceanographic environments.
著者
井関 弘太郎
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.84, no.5, pp.247-264, 1975-10-25 (Released:2009-11-12)
参考文献数
52
被引用文献数
5 8

Alluvial plains in the coastal regions of Japan are considered to have developed according to the following processes : during the last glacial stage when the sea level was lowered, rivers dissected their valleys downward to that level. After then, in consequence of the postglacial rise of the sea level, these valleys were drowned and were filled up with Flandrian deposits.The bottom floors of such buried valleys are mostly found at 30-80 meters below the present sea level. These bottom floors in many cases are covered with fluvial gravel beds about 10-20 meters thick. Such gravel beds are mostly overlaid with sediments of finer materials which deposited in the shallow sea during the late and post glacial transgression. They are called “Basal Gravel Beds” of the Recent deposits by the present author. They have probably been formed when the lowering of the sea level reached the limit during the last glacial stage. The huge accumulation of gravels as the Basal Gravel Beds might have been brought on by the overloaded streams which carried much detritus as the production of the strong physical weathering under glacial or periglacial conditions during the Ice Age. The author found that some of the Japanese alluvial fans of a large scale are formed by Recent Basal Gravel Beds.The maximum accumulation of the ice during the last glacial stage should be enough to cause a lowering of the sea level of about 80-15 meters below that of the present. In order to get a acceptable figure regarding the lowering of the sea level or the lowest sea level during the last glacial stage, the author, presuming the figures-100 and-140 meters as the postulated low sea level stand, examined the depth of these floors of buried valleys, respectively.Based on the results of borings which were carried out with 21 major buried valleys in Japan, the depth from the surface of present-day alluvial plain to the upper face of Basal Gravel Bed which covered bottom floor of buried valley was measured in each alluvial plain and then the relation between the depth of the deepest bore hole and the distance from the mouth of the old valley to that bore hole site was investigated (Fig. 3 and 4). The correlation coefficient between the depth and distance was also calculated.Fig. 3 indicates the case in which the sea level was presumed to be 100 meters below that of the present and Fig. 4 in the cases of-140 meters, respectively. Is is obvious from these two charts that the depth of the deepest bore hole negatively correlates with the distance from the mouth of buried valley to that bore hole site. So far as the correlation coefficients are concerned, being-0.870 and-0.890, respectively, the presumed figure of the latter seems to be more acceptable than that of the former. Therefore, judging from the depth of buried valley floors, the author is of the opinion that the figure-140 meters as the lowest sea level during the last glacial stage should be more acceptable than that of-100 meters.
著者
岡 義記 寒川 旭
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.90, no.6, pp.393-409, 1981-12-25 (Released:2009-11-12)
参考文献数
18
被引用文献数
1 3

Geographic Outline AWaji Island lies from NE to SW, dividing the east Inland Sea. The central range running in same direction continues to the Rokko mountains which are thought to have been elevated by crustal movement in Pleistocene (Rokko Movement). In the southern part of this island is the Yuzuruha mountains of Cretaceus sedimentary rocks which are a part of the series of mountain ranges on the north of Median Tectonic Line (MTL). In the plains of this island are seen hills of Pliocene deposits (the Awaji group) elevated from below the bottom of the Inland Sea.Purpose of Study The authors intended in this study to make clear the process of the formation of the east Inland Sea and Awaji Island. In order, they carried out the investigation on following points : 1. Relation between the Miocene deposits and the age of the formation of the erosion surface on the mountains in the north.2. Sedimentary process of the Awaji group.3. Faults and deformation of the Awaji group.Result of study The results obtained are as follows : 1. The morphology of the basement rocks (granitic rocks) in the north had been already gentle and undulating before the Kobe group deposited, caused by the Miocene transgression. The thickness of it reached a few hundreds meter in the north, but after regression the Kobe group was erosed down to basement. The mountains in the north were flattened again in this age.2. In Pliocene time, the area of the east Inland Sea depressed and deposited the Awaji group of gravel, sand, lacustrine silt and clay. In early stage, the lake began to be supplied with sand, and gravel from the area to the north of the island. In last stage, rivers originated to the south of MTL carried gravel (Goshiki-hama gravel) over MTL. to the lake.3. Goshikihama gravel is supposed to be contemporaneous with the Uchihata gravel, which is the lowest of the Osaka group (Yoshiki OKA 1978). The lower part of the Awaji group is suggested to be older than the Osaka group.4. The thickness of the Awaji group reaches 800 meter in the north and 300 meter or more in the middle part of the island. It indicates the depression of the Inland sea in Pliocene time.5. The fault movement in this island took place after the sedimentation of the Awaji group. Reverse and transcurrent faults by E-W compression have been discriminative since the middle of Pleistocene age.6. The faults can be divided, by strike, into three types, as follows : Type I (N60°E) The faults of this type caused the uplift of the Yuzuruha mountains in the south.Type II (N-SNE-SW) This type of faults caused the uplift of the central range of the island.Type III (N20°W) This type of faults are active reverse faults cut through the main range of the island.
著者
池原 研
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.107, no.2, pp.234-257, 1998-04-25 (Released:2009-11-12)
参考文献数
134
被引用文献数
1 1

Marginal seas, such are located as Bering Sea, Okhotsk Sea, Japan Sea, East China Sea, South China Sea and Indonesian seas, locate along the western rim of the Pacific. They have only a small area but are regions of high biological productivity, and thus expected to play an important role on global environment. Each of them has an unique characteristics on bathymetry, water exchange between the adjacent marginal seas and/or open ocean, primary productivity and volumes of fresh water input and terrigeneous material supply. Because they connect each other and to the open ocean through the shallow straits, characteristics of water masses flowed into the marginal seas were highly influenced by global sea level fluctuations. Furthermore, climatic change affected the volume of terrigenous supply to the seas. Therefore, paleoenvironments of the marginal seas largely changed with long-term sea level changes and short-term climatic changes. Recent studies on paleoceanography of the Japan Sea and the South China Sea suggest the importance of Asian monsoon to control the oceanic environments of the marginal seas. Hemipelagic sediments with higher sedimentation rates in the marginal seas recorded paleoceanographic changes in high resolution. Multidisciplinary studies for large-diameter long piston cores from the East Asian marginal seas may provide good information for global climate changes in the late Quaternary.
著者
石川 有三
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.110, no.4, pp.592-601, 2001-08-25 (Released:2009-11-12)
参考文献数
26
被引用文献数
4 4

The shape of the Philippine Sea slab beneath southwest Japan was investigated using the hypocenter distribution and the fault plane solutions obtained by Japan Meteorological Agency. Two seismic belts were found in an equal depth section of the slab and these did not relate to the double seismic zone in the subducting slab. Then, the existence of a broken off piece of slab was proposed beneath Kii channel. This piece collided with Philippine Sea slab and created a high seismicity area at each side.Three events that were not located at a high seismic area in the slab were found. Two were considered to be the events that occurred at the near aseismic part of the slab. The other may have occurred at another broken off piece of the slab.
著者
ダビターヤ F. F.
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.76, no.3, pp.154-158, 1967

自然は絶えず変化している。自然のままの状態では気候の変化が最も速やかに行なわれ, 植生や地形の変化は何世紀, 何十万年という速度で進行する。しかしいったん人為が加わるとそれぞれ変化の速度が異なってくる。人為の影響を受けやすいのは植生で, 気候はいちばん遅れて変化が現われるようになる。気候・植生・土壌などによる地域区分の境界線が一致しないのは, それぞれ変化の速度に違いがある以上当然だといえる。<BR>今世紀になってから人間の活動はますます活発になって, 森林の減少, 草原の砂漠化, 河川の汚染, 地たりの激化などが急速に進んでいるので, このままでは大きな弊害が生ずるであろう。影響を受けるのが遅いはずの気候でさえも人間の影響を無視できなくなってきている。Budykoの計算 (1962) によると年々太陽から得ている熱量は49kca1であるのに対して, 世界中の人間が出している熱量は0.02kcal/cm<SUP>2</SUP>/yrであるが, これが毎年10%ずつ増えているとすると100年以内に太陽からの熱量に匹敵する量になる。また, 人間活動によつて大気中の炭酸ガスの量が増加して気温が上昇することも考えられる。一方, 水蒸気量や雲量や塵埃量の変化がこれらの効果を強めたり弱めたりする。量的な研究はまだ進んでいない。<BR>最近50~100年間に気温の上昇が認められている。1940~50年から再び下降の傾向を示しているが, 上昇がもう終わってしまったのか, 一時的な変動であるのかは今のところわからない。気候の温暖化と氷河の後退との関係はなかなか複雑で一義的には決まらない。気候温暖化の主因は大気大循環にあると考えられているが, 地球全体が温暖化することを説明できない。炭酸ガス説も不十分である。人工発熱量も現在までのところ問題にならないくらい小さい。<BR>そこで気候温暖化の一因に大気中の塵埃量の増大が考えられる。ここに逆説的な観測事実が二つある。一つはコーカサスと中央アジア地方の高山で過去50~70年の間に, 降水量は同じか増加し, 気温は下降の傾向を示しているのに氷河が後退していること, もう一つは融けっっある氷の表面の温度が0度以上であることである。これらは最近大気中の塵埃量が増えてきていることで説明がっきそうである。<BR>大気中の塵埃は宇宙塵, 海成の塵埃, 火岸灰による塵埃, 風成の塵埃, 工業による塵埃などであるが, 最初の三つは少量で変化も小さい。大気中の全塵埃の70~75%を占める風成の塵埃は森林の伐採, 耕地の開拓などによつて近年急速に増加した。工業による塵埃も相当量にのぼる。ソ連各地の直達日射量の観測結果からも1920年ごろから塵埃量が著しく増加したことがわかる。<BR>このような最近の自然現象の変化の方向や強さを研究するためには, 全地球的規模の計画に従つて同時観測を実施することが必要である。そしてこのような観測の計画を樹てるためには世界各地の地理学者の協力がなければならない。
著者
大場 忠道
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.115, no.5, pp.652-660, 2006-12-25 (Released:2009-11-12)
参考文献数
11
被引用文献数
4 4

Five distinct paleoenvironmental changes in the Japan Sea over the last 95 ka are revealedfrom the oxygen and carbon isotopes of foraminiferal tests in a piston core recovered from the Oki Ridge. Between 95 and 27 ka, the warm Tsushima Current did not flow into the Japan Sea.The environment at the seafloor fluctuated between anoxic to weakly oxic conditions. Between 27and 17 ka, freshwater input to the Japan Sea, probably from the surrounding land, stratified the water column, and the resulting severe anoxic conditions eliminated most benthic fauna. Between 17 and 10 ka, the cold Oyashio Current flowed into the Japan Sea through the Tsugaru Strait, reestablishing deepwater ventilation. Between 10 and 8 ka, bottom conditions changed from anoxic to oxic. At 10 ka, the warm Tsushima Current started to flow into the Japan Seathrough the Tsushima Strait, establishing the modern oceanographic regime at 8 ka.From high-resolution oxygen and carbon isotope analysis of both benthic and planktonic foraminifera from an IMAGES core collected from off Kashima, central Japan, very large (20°C) sea surface temperature (SST) fluctuations can be reconstructed for the last 150 kyr, with minimum SSTs of 3-4°C during Marine Isotope Stage (MIS) 2 and MIS 6/5e transition, and with peak SSTs of 22-23°C during early MIS 1 and MIS 5a/4, 5c/5b, and 5e/5d transitions. The SSTs varied in parallel with changing carbon isotope differences between Globorotalia inflata and Globigerina bulloides, which suggests that the SST changes were primarily caused by latitudinal displacements of the Kuroshio-Oyashio Currents. A strong correlation between the SST shifts and orbital forcing indicates that latitudinal displacements of the Kuroshio-Oyashio Currents were influenced by summer insolation at 65°N.
著者
藤井 敏嗣
出版者
Tokyo Geographical Society
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.97, no.3, pp.209-213, 1988-06-25 (Released:2009-11-12)
参考文献数
22
著者
村田 明広
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.82-93, 1995-02-25 (Released:2010-11-18)
参考文献数
24

The Paleogene Hyuga Group of the Aradani Area in East Kyushu is regarded as an accretionary complex in the Shimanto Terrane. The Group was formerly inferred to form a melange including various sized blocks of sandstones, red and green siliceous mudstones, and basaltic volcanic rocks. The siliceous mudstones are not blocks in the melange, but occur as a low-angled thrust sheet of 40m thick.The Hyuga Group of the Aradani Area consists of four tectonic units;(1) lower chaotic unit, (2) siliceous mudstone unit, (3) mudstone unit, and (4) upper chaotic unit in ascending order. Each unit except for the siliceous mudstone unit forms a duplex structure, in which strata are imbricated, dipping 30° to 50° Each duplex is formed by mono-lithologic strata. The fundamental structure of the Paleogene Shimanto Terrane in Kyushu is characterized by low-angled nappe structures with stacked duplexes, in which duplexes lie one above the other, similarly to those of the Cretaceous Uchinohae Formation in South Kyushu.Original succession of the Hyuga Group is (1) basaltic volcanic rocks, (2) red and green siliceous mudstones of Middle Eocene, (3) black mudstones of Late Eocene, (4) sandstones and alternating beds of sandstone and mudstone of Late Eocene to Early Oligocene. Chaotic beds of melange facies originate from all above-mentioned strata. The siliceous mudstones, which are considered to be hemipelagic sediments, were subducted, and then formed a thrust sheet during underplating. The siliceous mudstones were probably situated in the decollement horizon, but did not flow as a lubricant layer.