9 0 0 0 OA 中部日本内陸に起きた被害地震(M≧6.4)の時空分布に認められる規則性
5 0 0 0 OA 日本列島のインバージョンテクトニクス
4 0 0 0 OA 活断層研究の進展―『日本の活断層』出版前後
- 著者
- 松田 時彦
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.2010, no.32, pp.87-92, 2010-03-31 (Released:2015-07-31)
- 参考文献数
- 23
3 0 0 0 OA 強震動予測に期待される活断層研究
- 著者
- 武村 雅之
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.2008, no.28, pp.53-63, 2008-03-31 (Released:2012-11-13)
- 参考文献数
- 37
Severe damage from the 1995 Hyogoken-Nanbu earthquake gave us a lesson that a cooperation of research of active fault and strong ground motion is very important for the prediction of strong ground motion from inland shallow earthquake. That is an ace of the scientific world for the mitigation of earthquake damage. In this paper we take up two subjects which are important to put the strong motion prediction to the practical use. One is to estimate the magnitude of a future big earthquake from the active fault data and the other is to estimate the upper level of strong ground motions caused by blind faults. Expectations for active fault research to realize a useful strong motion prediction are described.
2 0 0 0 OA 六ヶ所断層周辺における海成段丘面の変形と地形発達
- 著者
- 渡辺 満久
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.2016, no.44, pp.1-8, 2016-03-31 (Released:2016-10-21)
- 参考文献数
- 18
There are several marine terrace surfaces in the southeastern part of Shimokita peninsula, northeast Japan. They are classified into H1, H2, M1, M2 and M3 surfaces in descending order. The M1 and M2 surfaces are correlated with those formed in MIS 5e and in MIS 5a, respectively. The Rokkasho fault merging into the extensive submarine fault along shelf edge in the north has successively deformed these terrace surfaces, resulting in a 1-2 km wide flexural scarp tilting to the east on the M1 and M2 surfaces. Vertical offset of the M1 surface is over 30 m in the north and less than 20 m in the south. The flexural scarp extends at least 15 km to the south of the Takahoko Lake. The Detoseiho fault is a subsidiary branch fault of the Rokkasho fault developed in the Rokkasho flexural scarp. Because the M1 surface is bending toward the east (toward the coast), the sand layer composing of the M2 surface abutted on the monocline slope. Following movements of the Rokkasho fault have deformed the M2 surface in the same direction as the M1 surface, and consequently the M1 and M2 surfaces converged upon in the flexural scarp. This makes it very difficult to distinguish one from the other. Such geomorphic development should be strongly controlled by the activity of active fault differentiating tectonic relief and the width of flexural scarp reflecting the depth of tip of fault plane. Further examinations on active faults extending parallel to the coast lines are required to solve the problems.
2 0 0 0 OA 海域における活断層調査-現状と課題-
- 著者
- 岡村 行信
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.2008, no.28, pp.31-39, 2008-03-31 (Released:2012-11-13)
- 参考文献数
- 36
Method and result of offshore active fault survey were reviewed. Acoustic and seismic waves are widely used for offshore topographic and geologic surveys. Higher frequency acoustic waves have high-resolution but attenuate rapidly in water or sediments, thus they are mainly used for seafloor topographic survey or shallow high-resolution seismic profiling survey. Multi-narrow beam sounding provided evolutionary detailed seafloor topographic maps that clearly show fault traces. Lower frequency seismic waves are widely used for survey of deep sea and deep subsurface geology, but their resolution is generally too low to evaluate the activity of faults in late Pleistocene or Holocene time. Multi-channel seismic profiling survey and digital signal processing technology tremendously improved quality of seismic profiles. Offshore active fault maps around Japan were published in 1980's and 1990's based mainly on analyses of single channel seismic profiles. The events of active fault have been identified only in shallow bay areas using high-resolution seismic profiles and sediment cores. In contrast, it is generally difficult to determine events in open sea areas, because of low quality of seismic profiles. Multi-channel seismic profiling system using a high-frequency sound source made it possible to obtain high quality seismic profiles in the open shallow sea area and showed an active fault in the source area of the 2007 Noto-Hanto earthquake. In the deep sea, low-frequency seismic profiling system generally show clear geologic structure including active faults, but it is difficult to determine their activity in the late Pleistocene and Holocene period. Analyses of turbidites and dive surveys using submersibles have been conducted to determine the ancient events of fault activity in the deep-sea area. There is no enough data of offshore active faults, especially in very shallow marine area along coast.
2 0 0 0 OA 濃尾地震断層系根尾谷断層
- 著者
- 岡田 篤正
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.1987, no.4, pp.71-90, 1987-08-20 (Released:2012-11-13)
- 参考文献数
- 84
- 著者
- 鈴木 康弘 岡田 篤正 竹村 恵二 慶 在福 金 幸隆 廣内 大助 伊藤 愛 大石 超 中村 洋介 成瀬 敏郎 北川 浩之 渡辺 満久
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.2005, no.25, pp.147-152, 2005
The Ulsan fault extends for 50 km along the NNW-SSE direction in the southeastern part of the Korean Peninsula; this is one of the most important active faults in Korea. Its paleoseismicity has recently attracted considerable attention. With the support of KOSEF (Korean Science and Engineering Foundation), excavation studies of this fault were conducted in 1999 as a part of the Korea-Japan cooperative research at Kalgok-ri in Kyongju city. The results obtained are summarized as follows. (1) The Ulsan fault plane has an eastward dip of approximately 30 degrees and exhibits typical reverse faulting. (2) It was reactivated three times in the past 30,000 years, in particular, twice after the age of AT tephra (approximately 25,000 years BP). (3) A vertical displacement of approximately 0.8 m occurred during the fault event, and the amount of net slip along the fault plane is calculated to be 1.6 m.
2 0 0 0 OA 活断層に関する2~3の問題
- 著者
- 浅田 敏
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.1991, no.9, pp.1-3, 1991-10-31 (Released:2012-11-13)
2 0 0 0 OA 反射法による立川断層の地下構造
- 著者
- 山口 和雄 加野 直巳 横倉 隆伸 木口 努 田中 明子 佐藤 比呂志
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.1998, no.17, pp.54-64, 1998-12-29 (Released:2012-11-13)
- 参考文献数
- 32
A seismic survey was conducted across the Tachikawa active fault in the western suburbs of Tokyo metropolitan area. The deep structure and movement of the fault are discussed based on the CMP stacked seismic section together with the geological data published previously. The results are as follows:(1) A flexure, about 150 meters in width, underlies the flexure scarp of the fault and continues vertically down to 1000 meters in depth.(2) The displacement of the fa u lt is about 100 meters upthrow of the northeast side between 300meters and 600 meters in depth, while the displacement at basement depth is about 100 meters downthrow of the northeast side.(3) The northeast side o f the fault had subsided relatively to the southwest side in the past. The fault movement was stopped for a while. Then the fault movement was reversed and the northeast side has been upheaved up to now. This is an inversion tectonics of the fault movement.
2 0 0 0 OA 立川断層の最新活動について
- 著者
- 東郷 正美 佐藤 比呂志 池田 安隆 松多 信尚 増淵 和夫 高野 繁昭
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.1996, no.15, pp.1-8, 1996-11-29 (Released:2012-11-13)
- 参考文献数
- 16
By excavation of the Ochikawa-Ichinomiya remain located on the flood plain along Tama River near the boundary between Tama City and Hino City, Tokyo metropolitan area, a fault was found in young alluvium. This fault is regarded as the continuation of Tachikawa fault, a major active fault existing in the left bank area of Tama River, because it is located on the southeastern extension of Tachikawa fault line, and its strike is almost parallel to the Tachikawa fault.Detailed investigation of the fault outcrop made it clear that the last faulting event on the Tachikawa fault had occurred after A. D.1020-1158, the mid-Heian period. At this place, the last faulting event was dominantly strike slip with horizontal shortening of about 0.6 m.
2 0 0 0 OA 淡路島中部,先山断層の最新活動とその意義
- 著者
- 吉岡 敏和 水野 清秀 榊原 信夫
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.1997, no.16, pp.87-94, 1997-08-30 (Released:2012-11-13)
- 参考文献数
- 9
The Senzan fault is an active reverse fault directing N-S to NNE-SSW in the central Awaji Island. During the 1995 Hyogoken-nanbu earthquake, a characteristic surface break appeared along the Nojima fault located at the western side of the Awaji Island, however, no surface break had occurred along the Senzan fault. We excavated an exploratory trench on the Senzan fault to detect the age of the faulting events, and we confirmed a reverse fault making a contact between slope deposits and a granitic rock. The youngest age of the hurried soil deformed by the fault is 1161±67 AD. This means that the last faulting event of the Senzan fault occurred after the 12th Century. This event may correspond to the historical Keicho Fushimi earthquake in 1596 AD.
1 0 0 0 OA 1943年鳥取地震の地表地震断層
- 著者
- 金田 平太郎 岡田 篤正
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.2002, no.21, pp.73-91, 2002-06-30 (Released:2012-11-13)
- 参考文献数
- 35
Surface rupture with maximum right-lateral displacement of 150cm and length of about 1 lkm was observed during the 1943 Tottori earthquake of Mw: 7.0, which struck the eastern Tottori prefecture, southwest Japan. We compiled all the previous reports and papers regarding the surface rupture associated with the earthquake as precise location maps (Appendix 1) and a data table (Appendix 2). We also showed the slip distribution along the surface rupture (Fig.3).The trace of the 1943 surface rupture exhibited the large step and quite sinuous geometry compared with other strike-slip surface breaks. This observation probably means that the causative fault for Tottori earthquake is at the infant stage on its way of evolution based on the Wesnousky's fault evolution model (Wesnousky,1988). Most of the surface rupture during the earthquake occurred along the geomorphologically detectable active fault (Shikano-Yoshioka active fault system). Thus, we can recognize the possible surface faulting event around the epicentral area based on recent understanding of tectonic geomorpholgy. However, the length of the subsurface seismogenic fault is underestimated by the presently proposed method (Odagiri and Shimazaki,2000) and this sh ould lead to crucial underestimation of the seismic moment and also strong ground motions. The method to estimate the lengt h Df the seismogenic fault must be reestablished.
1 0 0 0 糸魚川-静岡構造線活断層系神城断層における地中レーダー探査
- 著者
- 木村 治夫 中西 利典 丸山 正 安藤 亮輔 堀川 晴央
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.2013, no.38, pp.1-16, 2013
The Itoigawa-Shizuoka tectonic line (ISTL), which is located between the NE and SW Japan arcs, is one of the most major tectonic lines in Japan. The N-S trending Kamishiro fault located in the northern part of the ISTL active fault system is an east dipping reverse fault. Near the southern part of the fault, the alluvial fan formed by a river flowing toward the southeast is tilted to the west by faulting. To reveal shallow subsurface deformation structure above a depth of 5 m, we carried out ground penetrating radar (GPR) profiling along two survey lines, whose lengths are 50 m and 130 m, respectively, across the fault. The GPR data was collected by common-offset modes using the control unit SIR-3000 (Geophysical Survey System Inc.) and the 200 MHz antenna Model-5106(Geophysical Survey System Inc.), and the station spacing was 0.01 m. The depth converted GPR sections after careful data processing are very concordant with the geological section based on drilling and trenching surveys conducted near the GPR survey. The GPR sections show deformation structure of the fan deposits in detail. The vertical displacement of the top of the fan gravel deformed by the Kamishiro fault is over 3.0 m during the last faulting event.
1 0 0 0 活断層GISデータを用いた地殻の歪速度の推定
The horizontal strain rate caused by fault activity for the past several hundred thousand years was calculated using the latest active fault database. Features of fault activity at the scale of the Japanese Islands were estimated, and the results were compared with the strain rates that the pre-existing literature showed.<BR>The strain rate required using the latest active fault database resembles the strain rate requ ired using the pre-existing data on active faults in the Quaternary period (Kaizuka and Imaizumi,1984). The distribution of the strain rate required from active fault data resembles the distribution of the strain rate required from the GPS observations (Sagiya<I>et al</I>.,1999) in many regions, with the exception of the Pacific coast region. However the value of strain rate required from active faults data (10<SUP>-8</SUP>/year) is smaller than the value of strain rate required from the GPS data (10<SUP>-7</SUP>/year). In the region along the Ou Mountains, Northeast Japan, the value of strain rate required from the latest active fault data was nearly equal to the strain rate required from the geological section (Sato,1989).
The Mw 7.1 (GNS Science) earthquake (Darfield earthquake) occurred near Christchurch, New Zealand on 4 September 2010. The earthquake happened in the area where active faults had not recognized previously, produced the ground surface rupture (Greendale fault). We surveyed the mode of occurrences of the Greendale fault on 8 days after the Darfield earthquake. Measured dextral and vertical displacements along the fault are ~ 4.2 and ~ 1.5 m (predominantly southern parts up), respectively. The both slip components are distributed roughly symmetrically along the west fault segment. However, the maximum displacement points are perhaps different between dextral and vertical sense based on the survey results. The fault is roughly E–W strike, characterized by many Riedel fractures that show shapes of mole tracks accompanying main dextral displacements. Few active faults had recognized previously on Canterbury plain near Christchurch, whereas distribution of active faults and folds had cleared in the Pegasus Bay area where locates in the eastern part of the Christchurch. Moreover, there are records of a few paleoearthquakes (M>5) near Christchurch and in Pegasus Bay. These data would have been clues to forecast existence of blind active faults on Canterbury plain.
1 0 0 0 OA 活断層の地中レーダ法によるイメージング:その現状と展望
- 著者
- 笠井 弘幸 阿部 信太郎 鈴木 浩一
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.1996, no.15, pp.73-86, 1996-11-29 (Released:2013-03-22)
- 参考文献数
- 5
Ground penetrating radar uses reflected electromagnetic waves to image the subsurface. Its investigation depth is 2-3m and its resolution is 20-30cm in soil. Because of its very shallow investigation depth, ground penetrating rbdar has been used for finding underground gas pipes, electric cables and buried remains.Ground penetrating ra d ar method has an advantage over the seismic reflection method in tenns of the spread density of sources and sensors. It is necessary in the seismic reflection method to spread sources and sensors in consideration of surface waves because the generation of surface waves makes it very difficult to distinguish reflected waves. However, in ground penetrating radar method, sources and sensors can be spread conveniently with high density for its high resolution because surface waves are not generated in the electromagnetic field.We have devised a new radar system to ap p l y the ground penetrating radar method to geological surveying. In the ordinary radar system, impulsive waves are used as transmission signals, but in the new radar system, sine waves are used with the frequency varied as a step function of the sweeping period of transmission signals. We can obtain the impulsive reception signals such as the ordinary radar system after the convolution integrals between sine-shaped transmission and reception signals. We call the new radar system the Step Continuous Wave Radar(SCWR) systen after the characteristics of its transmission signals. Its investigation depth is 10-15m in soil and 20-30m in rock with resolution of 50-60cm.The SCWR system will provide useful information because it can be carried out speedily and non-destructively on the ground around active faults, before trenching, down to about 10m in depth.In this paper, we will show the imaging of active faults with the SCWR system throu g h the results of the investigation around the Nojima faults which appeared in the Awaji Island with the 1995 Southern hyogo Prefecture Earthquake, and then we will pick up some current problems in the imaging, for example the effective arrangement of sources and sensors for the shorter period of field work and for the three-dimensional imaging with ground penetrating radar, and finally show a conception for the solutions of these problems.
1 0 0 0 OA アメリカ合衆国の活断層データベースとその応用
- 著者
- 奥村 晃史
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.2003, no.23, pp.5-12, 2003-06-30 (Released:2012-11-13)
- 参考文献数
- 21
Geologists and seismologists in the United States have been compiling and publicizing databases on possible sources of earthquakes including active faults since early 1970s. The ideas about the database and risk assessment have evolved in close response to public demands raised by such unforeseen earthquake hazards in 1 989 Loma Prieta earthquake and 1994 Northridge earthquake. Though the forecasts of future earthquakes failed repeatedly, the scientific communities always analyzed the failure and improved the knowledge and technology. The faultrupture hazard zone mapping under the Alquist-Priolo act was supplemented by the seismic hazard mapping of liquefaction and landslides. Probabilistic earthquake hazard mapping of Southern California and entire United States clearly demonstrated the advantages of regional ground shaking assessment to the evaluation of fault activity.
1 0 0 0 OA 活断層研究の歴史と課題
- 著者
- 松田 時彦
- 出版者
- 日本活断層学会
- 雑誌
- 活断層研究 (ISSN:09181024)
- 巻号頁・発行日
- vol.2008, no.28, pp.15-22, 2008-03-31 (Released:2012-11-13)
- 参考文献数
- 95
That faults are the origin of earthquakes was not an accepted theory in Japan for several decades prior to 1960, although the progressive accumulation of fault displacement in the Quaternary Time had been demonstrated in seismic areas. The Earthquake Prediction Program proposed by seismologists in 1962 stimulated geologists and geomorphologists to start active fault studies.During the 1960-1970's, the following results were made clear: 1) the distribution of active faults in onshore Japan, shown in 123 sheet maps of 1: 200,000 scale with detailed inventories by the Research Group for the Active Faults of Japan; 2) the extensive occurrence of strike-slip type active faults, almost none of which was known on the Japanese Islands at that time; 3) the existence of Quaternary crustal stress field with east-west compression in most of the Japanese Islands, recognized from the conjugate fault system of the central Japan; 4) the quantitative relation between earthquake magnitude and length of the surface trace of co-seismic fault for the onland Japanese earthquakes, which has been used in Japan to estimate magnitudes of future earthquakes; 5) the very long recurrence intervals of activity of a fault, generally longer than the order of 1000 years.In 1980-1990's, especially after the 1995-Kobe earthquake, excavation studies were performed extensively in more than one hundred active faults in onshore Japan. The active fault data obtained so far made it possible to prepare seismic hazard maps with probabilities of the occurrence of strong seismic motion in a specified period.