出版者

[富士マイクロサービスセンター]

巻号頁・発行日

1942

出版者

大分合同新聞社

巻号頁・発行日

0000

出版者

朝日新聞社

巻号頁・発行日

0000

著者

岡村行信 [著]

巻号頁・発行日

1991

著者

荒井 晃作 岡村 行信 井上 卓彦 池原 研 佐々木 智之

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.2011, pp.222, 2011

著者

岡村 行信 井上 卓彦 阿部 信太郎

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.2014, 2014

著者

木村 治夫 岡村 行信

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.2009, pp.217, 2009

著者

廣田 明成 蒲生 俊敬 角皆 潤 竹内 章 張 勁 山越 祐子 岡村 行信

出版者

一般社団法人日本地球化学会

雑誌

日本地球化学会年会要旨集

巻号頁・発行日

vol.49, pp.35, 2002

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日本海東縁部の冷湧水活動にともなうバクテリアマット域で「よこすか/しんかい6500」YK01-06航海において海底直上水および間隙水のサンプリングを行い化学成分の分析とデータ解析を行った。その結果として湧水から高濃度で炭素同位体比の軽い微生物起源のメタンが検出された。また間隙水中のメタンは堆積物中の微生物による酸化が進行していることが分かった。

著者

岡村 行信

出版者

国立研究開発法人 産業技術総合研究所

雑誌

Synthesiology (ISSN:18826229)

巻号頁・発行日

vol.5, no.4, pp.234-242, 2012

被引用文献数

7

---

歴史文書に記録されている西暦869年貞観地震を解明するため、地層に残された津波堆積物を詳細に調査し、津波の数値計算を組み合わせて津波規模を推定した。2011年東北地方太平洋沖地震は、その推定よりかなり大きかったが、津波堆積物が過去の巨大津波の証拠であり、巨大津波の警告であることを証明した。この貞観地震に関する研究成果は地震調査研究推進本部に提出され、2011年3月にはおよそ評価が終わっていたが、社会に周知する直前に地震が発生してしまった。このようなことを繰り返さないためにも、巨大地震に関する研究成果はできるだけ早く社会へ伝える必要がある。同時に、信頼できる研究を進めることも重要である。

著者

岡村 行信

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.71, pp.185-199, 2019

被引用文献数

5

---

<p>An active fault map of Japan Sea was compiled based mainly on bathymetric data and seismic profiles that cover shelves to slopes between 4 to 150 km from the coasts of Japan Islands. The seismic profiles using air guns as seismic sources revealed active faults that have slipped during the last 104 to 106 years. In addition, high-resolution seismic profiles using a boomer as the seismic source were obtained along seaward extensions of onshore active faults in shallow sea areas less than 150 m below sea-level, and activity of the faults during the last 104 years was identified. In northeastern Japan Sea, to the northeast of the Noto Peninsula, many reverse faults accompanying large hanging wall anticlines (>750 m uplift) are concentrated in two N-S trending fault zones along the Okushiri and Sado ridges. Earthquakes larger than M 7.5 in 1940, 1964, 1983 and 1993 occurred in these fault belts. Three NE-SW trending fault zones cross the N-S trending fault zones and disrupt the structure of the N-S fault zones. In the offshore area from the Noto Peninsula to the Tango Peninsula, active reverse faults accompanying smaller hanging anticlines (<375 m uplift) are identified in a zone trending subparallel to the coasts. In addition, NW-SE to N-S trending strike-slip and reverse faults extend from onshore to offshore. In the offshore area to the west of the Tango Peninsula, E-W and NW-SE trending active strike-slip faults are identified. The former faults developed in about 40 km wide zones sub-parallel to the coast, and the later faults are located landward of the E-W trending fault zones. Some of the later faults are extensions of onshore active faults. Unknown active faults may exist in shallow sea area along coasts where have not been thoroughly investigated. Displacements of the faults during the last 106 years are large in northeastern Japan Sea and decrease to the southwest, while slip rates of these faults during the last 104 years are inferred to have smaller differences. These faults have the potential of future earthquakes, while there is not enough data to evaluate the activities of these faults.</p>

著者

荒井 晃作 岡村 行信 倉本 真一

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.1998, 1998

著者

岡村 行信

出版者

石油技術協会

雑誌

石油技術協会誌 (ISSN:03709868)

巻号頁・発行日

vol.65, no.1, pp.40-47, 2000

被引用文献数

11

---

The eastern margin of the Japan Sea has rifted in the early Miocene. Then it hascompressed during the late Pliocene through the Quaternary. This change of stress caused basininversion along the margin, but the inversion structures vary mainly due to difference of therifting structures. In this paper, three types of basin inversion were defined. Type A basininversion is characterized by simple inversion of half grabens. Miocene normal faults reactivatedas reverse faults and the whole grabens have been uplifted. Many basin inversions of this typehave been widely formed in the Sado Ridge and Mogami Trough in the southern part of theeastern margin of the Japan Sea, to the west of the Tohoku Arc. Type B basin inversion isdefined by anticlinoriums in the major rift basins along the coastal zone of the Tohoku arc. Therifts have been partly uplifted by reverse faults and asymmetric anticlines, suggesting that partsof the extensional faults in the rifts have reactivated. Type C basin inversion forms the OkushiriRidge which continues in the N-S direction along the eastern margin of the Japan Basin to thewest of Hokkaido. It is not clear that the ridge has overprinted on the preexisting extensionalfaults. Reverse faults in the three types of basin inversion are accompanied by asymmetricanticlines or anticlinoriums. The profiles of the anticlines suggest that hinges of the anticlineshave been fixed during the growth of the anticlines. These structure and growth pattern of theanticlines can be explained by listric reverse faults and detachments at 10-20km in depth. Thegeologic structure related with extensional tectonics are generally obscure due to the lack ofpre-rift sedimentary sequences and extensive activity of volcanism in the rifting stage.Consequentry, it is difficult to clarify the relationship of the major fault systems between theextensional and compressional stages.

著者

岡村 行信

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.1998, 1998

著者

伊藤 弘志 植木 俊明 岡村 行信

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.28, no.1, pp.p1-1-P1-6, 2016

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To estimate the scale and feature of earthquake, the location and geometry of faults are important information. Japan Coast Guard conducted the seismic reflection survey in the focal area of the 1964 Niigata Earthquake in order to extract the location and geometry of faults in 2004, but tectonic geomorphological implications were not considered then. In this study the parameters of the multibeam echo sounder were estimated and the location and geometry of faults were extrapolated from the geographic map. They almost corresponded with the distribution of faults evaluated on the seismic reflection profile. More certain structural map was compiled from both results.

著者

岡村 行信

出版者

Japanese Society for Active Fault Studies

雑誌

活断層研究 (ISSN:09181024)

巻号頁・発行日

vol.2008, no.28, pp.31-39, 2008

---

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.

著者

佐藤 瑠美 張 勁 山腰 裕子 佐竹 洋 竹内 章 岡村 行信

出版者

一般社団法人日本地球化学会

雑誌

日本地球化学会年会要旨集

巻号頁・発行日

vol.51, pp.182, 2004

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2001年、北海道茂津多岬沖海底で、1km2弱の豹紋状巨大バクテリアマットが発見された。本研究は、この巨大バクテリアマットの生成メカニズム、海底冷湧水とテクトニクスの関連性を明らかにすることを目的とした。1999-2003年計10回の潜航調査により採取された柱状試料で、バクテリアマット下0-4cmbsfで、急激な硫酸濃度減少が見られ、硫酸還元菌も確認された。硫酸還元は、メタン又は有機物と反応するが、間隙水中のΔSO4とΔCa+ΔMgのモル比が1:1であることより、メタン起源であることが分かった。また、塩素濃度減少と、δ18O/δDの値から、メタンの起源がメタンハイドレートである可能性が大きいと推測され、堆積物中の有機炭素量にも支持された。さらに、斜面崩壊の痕跡と共にバクテリアマット下5-37cmbsfで強い硫化水素臭の砂利層が確認され、地殻熱流量の実測値と合わせた結果、砂利層を通って、メタン源からメタンが広域に供給されることが考えられる。

著者

小松原 純子 宍倉 正展 岡村 行信

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.2007, pp.367, 2007

著者

岡村 行信

出版者

一般社団法人 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.33, pp.15-25, 2010

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Geologic structure around the source area of the 2007 Chuetsu-oki earthquake and the Sado Basin was examined based on seismic profiles. The earthquake occurred in the fold belt of the Niigata basin, one of the largest Miocene rift basins in Japan. High-resolution multi-channel seismic profiles in and around the source area showed that there are active folds and inactive folds. One of the NE-SW trending active folds has been related to the SE dipping source fault of the 2007 earthquake, which continues from the shelf to the basin. The fold is parallel to the strike of the source fault of the 2007 earthquake, but is located about 5 km northwest of the source area. Other folds above and around the source area of the 2007 Chuetsu-oki earthquake are inactive. The active anticline accompanies 5 m vertical offset on the erosional surface during the last glacial age and the surface sediments covering the Sado Basin. The active anticline does not continue to the north of 37°38′N. The slope of the SE side of the Sado Basin is underlain by nearly horizontal sediments and the slope has been developed by progradation of shelf slope during glacial ages. These observations on seismic profiles indicated that the active fault and anticline related to the 2007 Chuetsu-oki earthquake does not extend to the northeast along the southeastern slope of the Sado Basin except in the southern most part.

著者

岡村 行信 柳沢 幸夫

出版者

実業公報社

雑誌

地質ニュース (ISSN:00094854)

巻号頁・発行日

no.607, pp.13-17, 2005-03

被引用文献数

3

著者

佐々木 智之 辻野 匠 川村 喜一郎 荒井 晃作 佐竹 健治 岡村 行信 三輪 哲也 玉木 賢策

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.2008, pp.388, 2008