著者
楠本 成寿 福田 洋一 竹村 恵二 竹本 修三
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.1, pp.32-43, 2001
参考文献数
35
被引用文献数
1 6

In order to solve a mechanical inconsistency that the Osaka Bay basin exists between the Median Tectonic Line (MTL) and Arima-Takatsuki Tectonic Line (ATTL) (right-lateral left-stepping faults), we attempted to investigate and evaluate the basin forming mechanism at the termination of right-lateral left-stepping faults by means of the dislocation modeling.<BR>The results of the numerical simulations show that the sedimentary basin can be formed at the termination of the right-lateral left-stepping faults develop, if the secondary fault caused by the rightlateral motion is a reverse fault and its displacement is larger than 20% of the lateral motion. We applied this model to the fault distribution in the Kinki district, and found that tectonic structures around the Osaka Bay can be explained by combination of 1) the right-lateral motion of the MTL and ATTL and 2) the reverse motion of their secondary faults, <I>i.e</I>., Nara-Toh'en Fault, Ikoma Fault and Rokko-Awaji Fault Systems.
著者
齋藤 有 田村 亨 増田 富士雄
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.114, no.5, pp.687-704, 2005-12-25
被引用文献数
3 3

Hyperpycnal flow is one type of turbidity current, which is generated at a river mouth when the suspended sediment concentration of river discharge is so high that the density of the effluent exceeds the water of the receiving basin. Generations of this type of flow have become a common phenomenon recently. A lot of hyperpycnal flow deposits are expected to be preserved naturally in stratigraphic records. Hyperpycnal flow deposits (hyperpycnites) might become an innovative factor for turbidite paradigm considering the particularity of the flow, and bring facies analysis towards the next step. In this review paper, the criteria for identifying hyperpycnal flow deposits from strata are proposed by summarizing studies on hyperpycnal flow and its deposits. Typical characteristics of hyperpycnal flow include : (1) vertical succession composed of 2 parts, inversely-graded lower part and normally-graded upper part, (2) internal scour surface, (3) repetitive alternation of fine-grained and coarse-grained layers, or laminated and massive layers, (4) abrupt pinch-out of beds, and (5) inclusion of terrestrial materials such as leaves. Hyperpycnal flow gradually waxes and then wanes to terminate in response to flood conditions, resulting in (1). The internal scour surface (2) developed in accordance with the degree of waxing. Fluctuations of flow velocity and sediment concentration due to changes of river discharge and/or internal waves can occur during the flow event, and lead to repetitive alternation of (3). Because of the fresh interstitial water, the marine hyperpycnal flow might start to lift off after losing suspended sediments to the degree that the density of the flow is exceeded by ambient saline water. This results in (4) at the lifting point. Terrestrial materials referred to in (5) are the result of the fact that the hyperpycnal flow originated from terrestrial floods.<BR>A much wider variety of deposits, which form in one history of a turbidity current, than that expected from the Bouma sequence model, is shown. Exploration of the variety has just started.
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 15

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
田中 和広 石原 朋和
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.118, no.3, pp.499-510, 2009-07-07
被引用文献数
5 3

The Nabetachiyama Tunnel 9116 m long was excavated in Tokamachi City, Niigata Prefecture and encountered the serious difficulties during excavation. In particular, a 600 m long section in the Matsudai area had experienced difficulties caused by swelling mudstone in the Tertiary Sugawa Formation. A 120 m bore hole long was excavated in the neighborhood of the section and geological and geochemical examinations of sampled cores were carried out to investigate the formation mechanism of the swelling rock mass. Mudstone distributed deeper than 50 m in the bore hole can be correlated to the tunnel troubled section geologically and geochemically. The section is assumed to be composed of mud breccia with mudstone fragments and clayey matrix, which is thought to be generated by hydro-fracturing of mudstone, showing weak strength due to large quantities of clay minerals. A gas pressure of 1.6 MPa thought to be caused by degassing of methane was measured during tunnel construction, which would increase the swelling properties. Mud breccia distributed deeper than 50 m contains a lot of Na-smectite formed in highly saline pore water ascending from deep underground. The result of slaking test showed that mud breccia filled with saline groundwater is characterized by quick slaking and swelling due to the marked contraction of Na-smectite when drying. In summary, the swelling rock mass distributed in the troubled section was formed by the weak rock strength caused by hydro-fracturing and high gaseous pressure generated by degassing. Furthermore, quick slaking caused by repeated wetting and drying was another reason for swelling during excavation.
著者
大和 広明 三上 岳彦 高橋 日出男
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.120, no.2, pp.325-340, 2011-04-25
参考文献数
12
被引用文献数
3 8

We analyze the influence of sea breeze on temperature distribution in the Kanto Plain (central Japan) on a day that a sea breeze front was detected (known as sea-breeze front days) using high-resolution temperature data observed by our research team.<br> The high-temperature area on sea breeze front days moves northwest from central Tokyo, and was located at Kawagoe city (middle Kanto Plain) at 14 JST, and the northern Kanto Plain at 16 to 18 JST, respectively. This high-temperature area appears at the head of the sea breeze front to the leeward of central Tokyo, where the daily maximum temperature is highest in Kawagoe city and the northern Kanto Plain. After the sea breeze front passes, the area where the temperature is higher than that at the circumference is distributed in the shape of a wedge. This wedge-shaped area is located to the leeward of central Tokyo where the wind from Tokyo Bay and Sagami Bay forms a convergence zone. The high-temperature area around Kawagoe city, which cannot be found on days with strong winds, is formed from the hindrance of cold air advection caused by sea breeze front penetration.<br> On the other hand, high temperatures in the northern Kanto Plain may not be related to the penetration of sea breeze fronts, which do not reach the northern Kanto Plain on days when the daily maximum temperature is recorded. However, the temperature in the northern Kanto Plain is higher on sea breeze days than on strong southerly wind days, and this suggests that local circulation plays an important role in causing high temperatures in the northern Kanto.
著者
小泉 格
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.116, no.1, pp.62-78, 2007-02-25
被引用文献数
3 6

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, <I>Td</I>' = (frequency of warm-water species) - (frequency of warm-and cold-water species) <SUP>-1</SUP>?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 <I>Td</I>' values correspond to a period of climatic deterioration under which cultural changes occurred in Japan. The paleoclimatic variations and the triple events of high <SUP>14</SUP>C in the atmospheric residual <SUP>14</SUP>C record denoted by Stuiver <I>et al</I>. (1991) are recognized in the diatom variations.<BR>A similar periodicity is also recognized in North Atlantic drift ice (Bond <I>et al</I>., 2001), concentrations of sea salt and terrestrial dust in the GISP2 ice core (O'Brien <I>et al</I>., 1995), in lake deposits from the Jura in France (Magny, 1995), Tibet (Gasse et al., 1991; Ji <I>et al</I>., 2005), and Alaska (Hu <I>et al</I>., 2003), and oxygen isotope variations from stalagmites in southern China (Wang <I>et al</I>., 2005) and Oman (Neff <I>et al</I>., 2001).<BR>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 T<SUB>2</SUB> event in the T<SUB>1</SUB>-T<SUB>4</SUB> 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 T<SUB>3</SUB> 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.<BR>In the south-to-north transect of the cores from both the Pacific and Japan Sea sides of Honshu, <I>Td</I>' 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
柳井 修一 青木 一勝 赤堀 良光
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.119, no.6, pp.1079-1124, 2010-12-25
被引用文献数
8 26

Median Tectonic Line (MTL) and Fossa Magna (Itoigawa-Shizuoka Tectonic Line) had long been considered to be the most critical fault boundaries controlling development of the Japanese Islands since Naumann (1885) and Kobayashi (1941). After the appearance of plate tectonics, several new interpretations emerged, <i>e.g.</i>, sub-surface Benioff plane for the MTL. In this paper, we propose that those tectonic lines, major faults, and Tanakura Tectonic Line (TTL) were formed through a process at micro-plate boundaries during the opening of the Japan Sea in the Miocene.<br> MTL could have been formed along the consuming boundary between the PHS plate and Japan Sea microplate, which has shifted southward to the Nankai trough, accompanying large-scale tectonic erosion. Fossa Magna was formed as a gigantic transform fault with a transtension component in the Medial-Japan Sea when opening was initiated. The eastern and western boundaries of the Japan Sea must be a strike-slip fault, corresponding to TTL to the east, and a newly proposed strike-slip fault called the West Kyushu Tectonic Line, respectively. Fossa Magna, a medial region defined by two NS-trending Miocene parallel faults in central Honshu, defined by Nauman (1885) could be interpreted to be the largest transform fault in the Medial-Japan Sea to offset the spreading axis when the Japan Sea opened.<br> It should be emphasized that large-scale tectonic erosion occurred in front of consuming plate boundaries facing the PHS and PAC plates oceanward during the opening of the Japan Sea. The volume of tectonic erosion is calculated to be 17,581,500 km<sup>3</sup>, which is equivalent to 2/3 of the present-day Japan arc crust, which is sufficient to reach the depth of the megalith between the upper and lower mantle boundary, even with 10 km thickness of materials eroded and transported along the Benioff zone.<br> Although MTL, Fossa Magna, and TTL are remarkable in the geology of Japan, these young faults never affected the orogeneses of Japan back to 520 Ma, which grew the continental crust of Japan. We propose that microplate boundary processes decreased the volume of the Japan crust.
著者
新井 智一
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.114, no.5, pp.767-790, 2005-12-25
参考文献数
47
被引用文献数
2

This study examines the interaction between the politics in Fussa City and the Yokota Air Force Base, that is "the politics of place, " from a range of political, economic, and cultural processes which maintain the existence of the base.<BR>Military bases are generally established for global geopolitical purposes. However, the establishment of a military base has cultural implications for the local communities where the base is located, i.e., increased concerns about crimes committed by seavicepersons and noise by aircrafts. Although these military bases have some serious impacts, especially in Japan, geographers have not yet examined the issues regarding a particular military base and the resultant politics in the city.<BR>On the contrary, since the 1980s, Anglo-American political geographers have paid more attention to "the politics of place" This refers to the local politics that occur due to the interaction between a structural constraint and the individuality of a particular place.<BR>Therefore, this study examines "the politics of place" on the Yokota Air Base in Fussa City, Tokyo, by using resources from the local newspapers, novels, magazine articles, and council proceedings.<BR>The results are as follows : (1) Owing to the independence between the U.S. Air Force and local political and economic actors, an urban structure and local economy that depended on the Yokota Air Force Base were constructed in Fussa Town after the establishment of the base in 1945; (2) because of this structure, the local economy became to depend on Air Force personnel as consumers; (3) however, due to a shift to the floating exchanging rate and a reduction in the population of the base in the first half of the 1970s, there was a decrease in the influence that Air Force personnel had on the local economy; (4) since the 1980s, an economic agent utilized the "atmosphere" and "image" adjacent to the base to revitalize the local economy; (5) furthermore, the mass media represented Fussa City as a "base town" and conducted a review of the city in the 1960s, thus contributing to its revitalization; (6) during the economic slump in the 1970s, some local political agents were against the existence of the base. However, successive mayors of Fussa City have accepted the existence of the base, and utilized the subsidies it receives from the national government in order to construct the urban infrastructure.
著者
田近 英一
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.116, no.1, pp.79-94, 2007-02-25
参考文献数
86
被引用文献数
3

Liquid water on the surface of the Earth might have frozen entirely at least 3 times during the history of the Earth (650 Ma, 700 Ma, and 2.2 Ga). Assuming such extreme conditions, the snowball Earth hypothesis explains several unusual geological features associated with glacial deposits in the Proterozoic glaciations. Life should, however, have faced serious crises during these glaciations because liquid water is necessary for life. In particular, survival of photosynthetic algae, which are supposed to have appeared before the Neoproterozoic glaciations, might have been difficult if the surface water froze completely. There would have been refugia for life during the global glaciations. Life could have survived if the equatorial ocean was not completely frozen (soft-snowball condition), or equatorial sea ice might have been very thin (on the order of 10 meters). Even if these conditions were not achieved, life could have survived in shallow hot springs around volcanic islands. It would be much more difficult for eumetazoa to survive such severe conditions if they appeared before the Neoproterozoic glaciations as suggested by molecular clock studies. The appearance of eumetazoa after the last global glaciation (Marinoan glaciation), as suggested by the paleontological record, however, avoids this problem.
著者
Mori Jim 加納 靖之
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.118, no.3, pp.492-498, 2009-07-07
参考文献数
16
被引用文献数
1 5

2006年5月26日に発生したジョグジャカルタ地震による地震動が,250km離れたインドネシアのSidoarjo泥火山の噴出を誘発した可能性について検討した。この泥火山は2006年5月から噴出を続けている。泥火山の近傍で生じた流体圧変化と地震発生の時間的な一致から,地震波がこの地域の地下流体の状態に影響を与えたことが示唆される。別の同規模の地震のデータを用いて,地震波による応力変化の大きさを見積った。応力変化はごくわずか(0.005から0.010MPa)であったが,他の地域であればこの程度の応力変化でも微小地震を誘発した場合がある。地震の数分後に流体圧変化が生じたようであり,これは地下流体が地震動に対して応答したことを示していると考えられる。2006年ジョグジャカルタ地震は,Sidoarjo泥火山で小さな流体圧変化をひきおこした可能性があるが,これが泥火山の噴出開始に直接関係しているかどうか評価することは困難である。
著者
吉田 明夫
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.103, no.3, pp.201-206, 1994-06-25
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
藤井 理行
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.114, no.3, pp.445-459, 2005-12-25
被引用文献数
4

This paper describes past climate and environmental changes during the past 101 to 105 year time scale obtained by recent studies on ice cores from Arctic and Antarctica. Shallow ice cores from Greenland and Svalbard show clear North Atlantic Oscillation (NAO) signals and explosive volcanic activities in the Northern Hemisphere and the equatorial regions. A deep ice core drilled to 2503 m at Dome Fuji, Antarctica covers the past 320 ka, which includes 3 glacial-interglacial cycles with Milankovitch cycles of about 20, 40, and 100 ka. Major chemical compositions and microparticle flux show high concentrations in glacials and low concentrations in interglain high-middle latitudes during glacial-interglacial cycles. The Dome Fuji deep ice core contains 25 visible tephra layers. An analysis of the chemical compositions shows the possible source volcanoes in and around the Antarctica.
著者
石橋 克彦
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.108, no.4, pp.399-423, 1999-08-25
被引用文献数
4 9

A large volume of historical documents in Japan show that great subduction earthquakes have repeatedly occurred along the Suruga-Nankai trough off southwest Japan since A.D. 684 with an interval of 100-200 years. They occurred as pairs of <I>M</I>8 events, one in the eastern half (Tokai earthquake) and another in the western half (Nankai earthquake), as was the case for the 1854 Ansei earthquakes, while sometimes occurring as single giant events like the 1707 Ho'ei earthquake. Although the space-time pattern of their recurrence is the best-known in the world, we should study more past events in order to understand the tectonophysical bases of their recurrence. In this respect I review the present understanding of historic Tokai and Nankai earthquakes and discuss related problems from the viewpoint of historical seismology. In this paper, the first of the three in all, I review the events until the early half of the 14th century. The keys to identifying older events are strong ground motion and damage in Kyoto, Nara, and Osaka, those in wider area of southwest Japan, tsunamis along the Pacific coasts of southwest Japan, typical coseismic vertical crustal movements of the Kochi plain, the Muroto and Oma'ezaki points, and the Ise and Suruga Bay coasts, temporal inactivity of specific hot springs, and aftershock activities recorded in Kyoto. The 684 Hakuho earthquake was definitely a Nankai event, and possibly included a Tokai event simultaneously (possibly Ho'ei type). The 887 Nin'na earthquake was also a definite Nankai event and was probably a Tokai event as well (Ho'ei type). The 1096 Eicho earthquake was clearly a Tokai event, but the following 1099 Kowa earthquake has some discrepancies that prevent it from being regarded as a <I>M</I>8 Nankai event. It is not clear yet whether great earthquakes occurred or not in the ca. 200 year intervals of 684-887 and 887-1096. It seems probable that great Tokai and Nankai earthquakes took place in the mid-13th century, but a more detailed investigation of historical seismology is required to discover the missing event.
著者
Radvanec Martin
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.118, no.4, pp.686-699, 2009-08-25
参考文献数
30
被引用文献数
1

この研究は,1945年8月6日,午前8時15分,広島の原子爆弾爆発による熱線の強力な影響を,2片の被爆瓦片を用いて研究したもので,この瓦片は元安川に架かる元安橋下流約100mの西岸で1977~1982年にかけて発掘されたものである。爆発から1.318秒後,爆心地で破壊された建物から衝撃波によって吹き飛ばされた大変熱くて融解した多数の破片は,元安川西岸に堆積した。この瓦片はおそらく,破壊された清病院の石塀,西向寺および(もしくは)西蓮寺からのもので,川の水で急激に冷却されたものと思われる。<br> 瓦片は安山岩質の火山砕屑岩からなり,その表面は3.18mmの深さまで融解していた。そのガラス質の層は,安山岩から玄武岩質安山岩の組成をもつ。これらはクリストバル石および/もしくはリンケイ石,ピジョン輝石(X<sub>Fe</sub> = Fe/(Fe + Mg)= 0.37-0.44),角閃石(X<sub>Fe</sub> = 0.33-0.42),曹灰長石(Ab<sub>48.2-40.6</sub>An<sub>51.8-55.5</sub>Or<sub>0-3.9</sub>)およびK-長石(Ab<sub>8.2</sub>Or<sub>91.8</sub>)が融解生成したものである。融解が3.18mmの深さにまでおよんでいることと,上記鉱物質のそれぞれ異なる融点および溶融深度から,爆発後の爆心地の物体表面の温度6287℃が算出された。この表面温度は,深さ2.68~3.18mmの区間における残存鉱物と,溶融深度の関係から導き出した。回帰直線<i>T</i> = -1715.1<i>d</i> + 6287(<i>d</i>は深さ)(<i>R<sup>2</sup></i> = 0.989)を外挿して求めたものである。安山岩瓦表層部の温度勾配は1mmあたり1715℃で,深さが2.86mmから3.18mmの間では,融解ガラス質と本来の鉱物質は等量である。3.64mm以下では,火山砕屑安山岩の構造および鉱物組成は,本来の組成を有している。
著者
鈴木 康弘 堤 浩之 渡辺 満久 植木 岳雪 奥村 晃史 後藤 秀昭 STREL'TSOV Mihail I. KOZHURIN Andrei I. BULGAKOV Rustam TERENTIEF Nikolai IVASHCHENKO Alexei I.
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.109, no.2, pp.311-317, 2000-04-25
被引用文献数
1 2

We have prepared a preliminary active fault map of Sakhalin, Russia, based on an interpretation of aerial photographs and satellite images. Major active structures include 110-km-long active faults along the western margin of the Yuzhno-Sakhalinsk Lowland in southern Sakhalin and 120-km-long active faults along the western margin of the Poronaysk Lowland in central Sakhalin. These active faults are parallel to but are located as far as 10 km east of the Tym-Poronaysk fault. Geomorphic surfaces on the upthrown side of the fault are tilting westward, therefore, the faults are considered to be west-dipping low-angle reverse faults. The vertical component of slip rates of these faults are >0.3 mm/yr in southern Sakhalin and 1.0-1.5 mm/yr in central Sakhalin. The net-slip rates could be much greater because the faults are low-angle reverse faults. If these faults rupture along their entire length during individual earthquakes, the earthquakes could be as great as M7.6-7.7. In northern Sakhalin, we have identified a series of right-lateral strike-slip faults, including the 1995 Neftegorsk earthquake fault. The slip rates for these faults are estimated at 4 mm/yr. The right-lateral shear in northern Sakhalin and east-west compression in central and southern Sakhalin may reflect relative plate motion in far-east Asian region.