著者

後藤 和彦

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.65, no.3, pp.231-242, 2013-01-31 (Released:2013-07-19)

参考文献数

28

被引用文献数

7 9

---

The hypocenter of the 1911 great earthquake occurred around Kikai-jima, Japan is thought to be 28.0°N, 130.0°E (about 30km southward from Kikai-jima) and 100km depth in general. This implies that the 1911 event occurred within the subducting slab at the Ryukyu trench. However, it is not clearly known what kind of seismic data were used to determine the epicenter and how the depth of hypocenter was estimated quantitatively. In the present study, we determine hypocenter of this event by using selected S-P time data not only reported ones but also re-measured ones from smoked-paper seismograms. The hypocenter is revealed to be 28.7°N, 130.6°E and 60km in depth, about 60km northeastward from Kikai-jima. The focal depth is, however, considered to be about 10km instead of 60km by referring to the present hypocenter distribution because of the low reliability of focal depth in the relocation. Recent epicenter distribution shows the low seismic activity area on the plate boundary northeast off Kikai-jima which extends about 70km length parallel to the Ryukyu trench axis. The 1911 great earthquake seems to be occurred at the shallower rim of this low seismic activity area. If the low seismic activity is the result of strong coupling on plate boundary, this area might be the asperity of the 1911 great earthquake. Tsunami heights accompanied with this event are reported recently to be more than 5m at Kikai-jima and Amami-oshima, which supports the present study that the 1911 great earthquake is the interplate event rather than the intraslab one.

著者

浜口 博之 後藤 和彦

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.34, no.1, pp.145-147, 1981-03-25 (Released:2010-03-11)

参考文献数

10

被引用文献数

1

著者

角田 寿喜 後藤 和彦

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.55, no.3, pp.317-336, 2002-12-15 (Released:2010-03-09)

参考文献数

107

被引用文献数

2

---

We reviewd characteristics of seismic activities in and around Kyushu and the northern half of Nansei Shoto (Ryukyu Islands), mainly on the basis of hypocenter distributions and focal mechanisms. Interplate and intraplate earthquakes, inclusive of intermediate-depth events, considerably differ in seismicity from region to region along the arc. Most of the boundaries between the seismic regions correspond to left-lateral tectonic lines geologically inferred and/ or narrow zones of crustal earthquakes of left-lateral strike slip types across the arc. Thus we surmise that the Philippine sea plate spiitted into several segments subducts with low coupling under the Kyushu-Ryukyu arc.Not only rifting along the Okinawa trough but also southeastward spreading from the Shanshi graben with left-lateral movements is probably important for crustal earthquakes of normal and strike-slip fault types dominant in an extensional stress field in the marginal sea and inland areas.

著者

後藤 和彦

雑誌

大衆文化 = Popular culture

巻号頁・発行日

vol.4, pp.24-36, 2010-09-30

著者

中尾 茂 八木原 寛 平野 舟一郎 後藤 和彦 内田 和也 清水 洋

出版者

日本地球惑星科学連合

雑誌

日本地球惑星科学連合2016年大会

巻号頁・発行日

2016-03-10

---

The earthquake (JMA Magnitude 7.1) occurred on November 14, 2015 in the area of west off Satsuma peninsula. The epicenter is located in Okinawa Trough where is in about 160 km west from Makurazaki City in Kagoshima Prefecture. This earthquake is one of the largest earthquakes in this area. Seismicity in this area is low in last twenty years. Two continuous GNSS sites are operated by Kagoshima University, one is UJIS site in Uji island which is 84 km to east from the epicenter and the other is MESM site in Meshima island which is 121 km north from the epicenter. At UJIS seismic observation is also operated by Kagoshima University and it is operated by Kyushu University at MESM. We went to those sites in order to get GNSS and seismic data because GNSS and seismic data are not telemetered at those sites. In this research, co-seismic crustal deformation and activity of aftershocks are reported.We relocated the main shock and aftershock until 10:00 on November 16. Length of aftershock area is about 60 km. Its Strike is the same of Okinawa Trough. The epicenter of the main shock is located at the south-west end of the aftershock area and maximum aftershock, which is occurred on November 15, is at north-east end. Activity of aftershock in northern part of aftershock area is high. However, in southern part it is low except aftermath of occurrence of the main shock.GNSS data analysis is by Bernese GNSS software Ver. 5.2 with CODE precise ephemeris. Daily site coordinates of UJIS and MESM are calculated with GEONET sites. Coseismic deformation is estimated by the difference between two days averages before and after the main shock. Displacement at UJIS and MESM is 0.82 cm and 0.65 cm, respectively. The theoretical coseismic deformation is estimated by a strike slip fault model (Okada, 1992). Fault length, strike, dip angle and fault position are estimated by the length of aftershock area. Fault width is assumed a half of the fault length. Amount of fault slip is estimated by the relationship between earthquake magnitude and moment (Sato, 1979). JMA moment magnitude 6.7 is used (JMA, 2015). Theoretical displacement at UJIS and MESM is 1.3 cm and 1.1 cm. Direction of observed displacement is coincident with that of theoretical displacement. However, amount of observed displacement is smaller than theoretical one.

著者

八木原 寛 角田 寿喜 後藤 和彦 清水 洋

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.47, no.1, pp.53-61, 1994-06-14 (Released:2010-03-11)

参考文献数

30

---

On January 30, 1992, a shallow earthquake of magnitude 4.9 followed by about 300 aftershocks occurred in a northern area of the Koshiki channel, north-western Kagoshima Prefecture. We located seismic events observed at two stations of NOEV (Nansei-toko Observatory for Earthquakes and Volcanoes) and four stations of SEVO (Shimabara Earthquake and Volcano Observatory), using Joint hypocenter determination (JHD). Hypocenters of the mainshock and its aftershocks were nearly vertically distributed at depths from 5km to 13km in a small area.Initial motions at the seismic stations of NOEV, SEVO and FMO (Fukuoka Meteorological Observatory) suggest a focal mechanism of strike slip fault type with a T-axis of NNW-SSE direction: the mechanism is very similar to those reported for the earthquakes in and around the area. The nodal plane striking in NE-SW agrees with trends of the fault system in the channel and the other WNW-ESE plane is parallel to the earthquake alignment along Amakusanada-Izumi-Kakuto areas. Hypocenters of the event and aftershocks nearly vertically distributing are, however, not consistent with any of the planes.In March of 1991, about 10 months before the M 4.9 event, an earthquake swarm (Mmax 2.9) occurred at depths around 5km almost within the same epicentral area. Namely, two different types of earthquake sequence occurred at different depths in the same area: the swarm occupied a shallower zone than the focal zone of the M 4.9 event. Although some volcanic process may be inferred from hypocenters vertically aligning, it is probably difficult to explain the fact that the earthquake swarm at shallow depths occurred about 10 months before the M 4.9 event at a deeper depth without accompanying any notable foreshocks.

著者

岡 真一郎 池田 拓郎 吉田 誠也 近藤 遥奈 筒井 友美 田中 晴菜 後藤 和彦 光武 翼 後藤 純信

出版者

日本神経眼科学会

雑誌

神経眼科 (ISSN:02897024)

巻号頁・発行日

vol.36, no.1, pp.36-43, 2019-03-25 (Released:2019-04-23)

参考文献数

20

---

バーチャルリアリティ(VR)を用いたニューロリハビリテーションの基盤研究として,2つの実験を行った.実験1では,右頭頂葉と視運動性眼振(OKN)および立位姿勢制御の関連機構について検討した.右頭頂葉の一過性機能抑制には,経頭蓋直流電流刺激の陰極刺激を使用し,OKNと身体動揺を計測した.その結果,右頭頂葉の感覚情報処理は視運動性眼振および開眼時立位姿勢制御と関連していることが示された.実験2として,完全没入型のスマートフォン用ヘッドマウントディスプレイ(S-HMD)を使用し,視運動刺激(OKS)がバランス能力に与える影響について検討した.その結果,OKS後は静止立位および左右片脚立位の開閉眼条件での姿勢制御機能が向上した.運動先行型の脳機能を賦活するニューロリハビリテーションは,リハビリテーションの効果を高める可能性を有することが示された.民生用HMDは,VRによるニューロリハビリテーションを臨床現場へ広く普及させるためのデバイスとしてのポテンシャルを秘めている.今後,HMDを用いたニューロリハビリテーションの推進を期待する.

著者

緒方 誠 岩田 訓 後藤 和彦

出版者

日本地球惑星科学連合

雑誌

日本地球惑星科学連合2016年大会

巻号頁・発行日

2016-03-10

---

桜島の大正大噴火の際、1914年(大正3年)1月12日18時28分頃に発生した地震については、当時の震度分布や被害等から鹿児島湾に震源があり、その規模はM7.1というのが現在の通説となっている(Omori(1922)、宇津(1982:気象庁カタログ採用)や、阿部(1981))。今般、大正噴火から100年が経過し、次の大正級噴火が近づく中、現存する地震記象紙や原簿・文献等を再点検し、現在気象庁で使用している速度構造(JMA2001)を用いて震源位置の再評価を試みることにした。この地震については、当時、鹿児島測候所に設置されていたグレー・ミルン・ユーイング式地震計の地震記象紙が現存しており、強震動の初動部分のみ記録し、その後は記録針が振り切れて記録は途絶えている。今回の調査では波形をデジタイズし、初動部分の解析を行った。その結果、初動から期待される震央の方向は、鹿児島測候所(鹿児島市坂元町)から見て南東象限であることが明らかとなった。次に、文献や原簿等に記載された日本国内(一部当時の統治領含む)のS-P時間(初期微動継続時間とされているもの)について収集・整理を行った。この際、地震記象紙が現存しているものについては、可能な限りP相、S相の読み取りを行った。そして、収集したS-P時間データを用いて震源決定を行った。S-P時間を収集した観測点数は20数点となったが、原簿や文献、読み取り値により同一観測点で複数の値が存在し、その値が大きく異なる場合もあるため、後藤(2013)が1911年喜界島近海の巨大地震の震源再評価で用いた手法を参考に震源計算に使用する観測点やS-P時間の選別を行った。最終的には、9観測点のS-P時間データで震源計算を行い、鹿児島市付近に震源が求められた。なお、震源計算には、気象庁カタログ(過去部分)の改訂作業に使用しているツール(走時表は、気象庁が現行の震源計算に用いているJMA2001準拠であるが、観測点の距離による重みは観測網を考慮しJMA2001前に使用していたもの)を使用している。本調査には、気象官署が保管している地震記象紙を地震調査研究推進本部が(公財)地震予知研究振興会に委託して行っている強震波形収集事業で高解像度スキャンしたファイルのほか、国立国会図書館、東京大学地震研究所所有の資料を使用しました。

著者

角田 寿喜 後藤 和彦 宮町 宏樹 平野 舟一郎 清水 力 岩切 一宏 中辻 剛 立山 清二

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.106, no.4, pp.476-485, 1997-08-25 (Released:2009-11-12)

参考文献数

26

被引用文献数

1

---

A shallow earthquake of MJMA 6.7 on October 18, 1995, at about 50km southeast off Kikai-jima in the Ryukyu Islands caused slope landslides, subsidence of concrete slabs at fishing ports and collapses of walls piled up with coral ragged stones. Several fishing boats moored to wharves were damaged by tsunami; four boats were turned over at ports in Amami-Oshima.From May 19 to 30, 1995, earthquakes of MJMA≤4.1 had occurred in the focal area after a long seismic quiescence since the 1911 Kikai-jima Earthquake of M=8.0. Some of them were felt in JMA intensity 1 or 2 at Kikai-jima. Numerous felt shocks also struck the island immediately after the main shock; 62 and 125 shocks on October 18 and 19, respectively. Numbers of aftershocks decreased rapidly, though they lasted through the end of 1996.The damage distribution of the 1911 event being compared with that of the 1995 event, their focal areas were considered to overlap with each other. It was, however, possibly an interplate earthquake of a thrust fault type in contrast with the 1995 event of a normal fault type in the subducting plate, because the first motions of P wave at Naze and of tsunami wave at Kikai-jima were reversed between the two events.

著者

八木原 寛 角田 寿喜 宮町 宏樹 後藤 和彦 平野 舟一郎 日野 亮太 金澤 敏彦 海宝 由佳 塩原 肇 渡邊 智毅 望月 将志 根本 泰雄 島村 英紀

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.49, no.2, pp.227-239, 1996-08-23 (Released:2010-03-11)

参考文献数

23

被引用文献数

1 1

---

We investigated seismic activity around Tokara Channel north off Amami Oshima, Nansei Syoto (Ryukyu) Islands of western Japan, using 12 ocean-bottom seismographs (OBS), as well as two temporal stations at Yaku Shima and Amami Oshima islands, operated from April 16 to May 10, 1992. One-dimensional velocity structure and station corrections were inverted from P and S times of 51 events provisionally well-located in the OBS network. We then relocated precisely 239 events in the studied region, using the inverted velocity structure and station corrections.Seismicity was highest in an area of about 10km×10km near the trench axis northeast off the OBS network: the largest event of MJMA 5.6 and other 40 events (probably aftershocks) were located at shallow depths. A mechanism solution of normal fault type with a T-axis of NW direction for the largest event was concordant with bending process of the Philippine sea plate. On the other hand, 18 events at depths of about 30km in a small area north of the OBS network were presumably due to interplate thrusting, because a composite mechanism solution for three events was of reverse fault type with a P-axis of ESE direction. A cluster of 17 events at depths from 10km to 25km was found in a southwest area of the network. These shallow events were probably crustal earthquakes within the Eurasian plate.We found an area of very low seismicity in the southeast of the network during the period studied. It is also identified at the nearly same location in the epicenter distribution from 1984 through 1991 obtained by Japanese Meteorological Agency (JMA) and possibly corresponds to the aftershock area of the 1911 Kikaijima Earthquake (M 8.0).Although we could not confirm any discernible alignments of shallow earthquakes along the Tokara Channel which is a notable tectonic line, the dipping angle of the intermediate-deep seismic zone changes discontinuously from about 65° on the north of the channel to about 40° on the south.

著者

向吉 秀樹 林 広樹 内田 嗣人 吉崎 那都 武田 哲也 後藤 和彦 関根 秀太郎 笠原 敬司

出版者

一般社団法人 日本地質学会

雑誌

地質学雑誌 (ISSN:00167630)

巻号頁・発行日

vol.124, no.5, pp.361-366, 2018-05-15 (Released:2018-06-30)

参考文献数

15

被引用文献数

2

---

In 1997, two strong earthquakes occurred on March 26 (Mj6.6) and May 13 (Mj6.4) in the northwestern part of Kagoshima Prefecture, Japan (termed the 1997 Northwestern Kagoshima Earthquakes). However no seismogenic faults associated with these earthquakes had previously been recognized at the surface. In this study, we report structural observations from newly recognized fault outcrops located 1.5 and 2 km southwest of the epicenter of the Mj6.6 earthquake. One outcrop consists of the Miocene Shibi-san Granodiorite, which is unconformably overlain by lower sandy loam, lower humic soil, upper sandy loam, and upper humic soil layers that are clearly offset by steeply dipping faults. We measured ~ 40 cm of vertical separation of the contact between the lower sandy loam and lower humic soil layers along a WNW-trending fault, above which the ground surface flexed upward by about 20 cm. The second outcrop is a streambed exposure of the Shibi-san Granodiorite that shows a 30-cm-thick layer of foliated cataclasite along a fault plane, with textural evidence of sinistral slip.

著者

白根 礼吉 小松 崎清 後藤 和彦 坂根 巌夫 末武 国弘

出版者

一般社団法人 映像情報メディア学会

雑誌

テレビジョン (ISSN:18849644)

巻号頁・発行日

vol.31, no.3, pp.270-282, 1977-03-01 (Released:2011-03-14)

著者

増井敬二三善清達後藤和彦共著

出版者

[出版者不明]

巻号頁・発行日

0000

著者

Castle Terry 後藤 和彦

出版者

青土社

雑誌

現代思想

巻号頁・発行日

vol.17, no.2, pp.p169-193, 1989-02

著者

後藤 和彦

出版者

立教大学

雑誌

基盤研究(C)

巻号頁・発行日

2009

---

本研究は、19世紀中葉における後発近代化を共有するアメリカ南部と近代日本において、「敗北の文化」に惹起され産出された公的文化言説、「ナショナル・ナラティヴ」が、その後に出現してきた私的言説としての文学にとってどのような意義をもったか、さまざまな文化テクストの実証的な分析によって歴史的に跡づけ、今後の両文学の本格的比較研究への新しい視座を切り開いた。