著者

髙橋 利昌 浅野 彰洋 大内 泰志 川崎 真治 武村 雅之 神田 克久 宇佐美 龍夫

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.60, no.3, pp.193-217, 2008-02-15 (Released:2013-08-20)

参考文献数

40

被引用文献数

1 1

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The major earthquakes of M=7 class, so-called Geiyo earthquake, have occurred in the subducted slab of the Philippine Sea plate under Aki-nada and Iyo-nada sea. The upper surface of the Philippine Sea plate is located in the depth from 40-45km in this region. Five Geiyo earthquakes can be found in 1649, 1686, 1857, 1905, and 2001 since 17th century. Magnitudes M of the older 4 events were larger than 7, while that of the last one is 6.7 in JMA (Japan Meteorological Agency) scale. Magnitudes and locations of focal regions of them were redetermined from seismic intensity data by the method of an attenuation curve fitting and of the seismic intensity inversion. Optimal magnitudes of old events were obtained between 6.7 to 6.9. This results show the old 4 events have almost the same magnitude as the 2001 event. One of the possible reasons why the former values were overestimated is that the empirical relation between magnitude and isoseismal area from inland shallow earthquakes was applied to determine the magnitude of the historical intraslab events such as Geiyo earthquakes.

著者

諸井 孝文 武村 雅之

出版者

一般社団法人日本建築学会

雑誌

学術講演梗概集. B-2, 構造II, 振動, 原子力プラント (ISSN:13414461)

巻号頁・発行日

vol.2008, pp.667-668, 2008-07-20

著者

中井 春香 武村 雅之

出版者

公益社団法人 日本地震工学会

雑誌

日本地震工学会論文集 (ISSN:18846246)

巻号頁・発行日

vol.17, no.2, pp.2_23-2_37, 2017 (Released:2017-05-30)

参考文献数

26

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1945年1月13日午前3時38分に発生した三河地震(M=6.8)の特徴としては, 全潰家屋数に対して死者数が多い地震であることがあげられる.その要因を明らかにするために, 戦時中であったこと, 地表地震断層が現れたこと, 1944年東南海地震(M=7.9)の約1か月後に発生したこと等に着目した.本稿では, それらの要因を定量化するため全潰家屋数を死者数で割ったNk値を用いて検討した.三河地震のように震動を主な被害要因とする地震では, 通常Nk値は10程度となるが三河地震はNk=3.1である.戦争の影響についてデータを元に検討した結果, その影響は少なくとも0.4程度Nk値を引き上げることが分かった.次に被害町村を死者数が多い順とNk値が低い順にそれぞれ並べた表を作成した.死者数では震度7となる岡崎平野に位置する町村が上位に並び, 地表地震断層が通った地域が必ずしも上位に並ぶわけではない.一方, Nk値が低い順に並べた場合は地表地震断層が明瞭に現れた町村が上位に多いことが分かった.そこで地表地震断層近傍の町村を一旦除き, 三河地震のNk値を算出すると, Nk値は3.9となり0.8程度Nk値を引き上げることが分かった.さらに上位に並んだ断層近傍地域を細かく見ていくと断層の上盤側の断層から約1kmの範囲で, 縦ずれの断層変位がより多い地域において被害が集中的に発生していた.特に縦ずれの断層変位が多い地域でNk値が1.1から1.2と低いことが判った.このことは, Nk値を小さくする原因として地表地震断層近傍で現れる断層変位や, 震源近傍の特有なパルス的地震動(キラーパルス)などが建物を一瞬にして全潰させて一挙に多くの死者を出したことを示唆するものである.また, 東南海地震が1か月前に発生していたことや発生時刻が真冬の夜中であり迅速な避難をより困難にしたこともその傾向を助長した可能性がある.

著者

武村 雅之

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.69, no.577, pp.153-159, 2004-03-30 (Released:2017-02-08)

参考文献数

18

被引用文献数

1

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A famous result for the damage in Tokyo Metropolis during the Kanto earthquake was that the damage rate of dozo (Japanese traditional timber storehouse coated with clay and plaster finish) is larger in the Yamanote terrace formed by diluvial deposit than that in the Shitamachi low-land by alluvial deposit, while the damage rate of wooden houses, which determined seismic intensity, was smaller in the Yamanote terrace than that in the Shitamach lowland. We re-examined the original data of dozo on the Kanto earthquake and compared with the damage data from the 1948 Fukui earthquake and the 1855 Ansei-Edo earthquake. It can be found that the original data was strongly contaminated by the damage due to fires during the Kanto earthquake, and that the result of dozo was not trusted. The damages of RC buildings and brick buildings which had almost the same natural period as dozo, were also re-examined. We could correlate weakly the damage rate of them with seismic intensity determined from the damage rate of wooden houses, which was larger on the alluvial deposit than on the diluvial deposit.

著者

武村 雅之

出版者

北海道大学大学院理学研究院自然史科学部門(地球物理学)

雑誌

北海道大学地球物理学研究報告 (ISSN:04393503)

巻号頁・発行日

no.73, pp.1-22, 2010-03

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The Great Hanshin-Awaji Earthquake Disaster in 1995 killed more than 6000 people. At that moment, the Seismological Society of Japan and the Japanese government examined themselves and fully recognized that communications beneficial for disaster prevention were not sufficiently exchanged and valuable knowledge obtained from earthquake research were not efficiently applied to the general public and disaster prevention organizations. The Seismological Society of Japan established new committees in charge of publicity and education in 1996 to provide opportunities of the communication between seismologists and general public. The Japanese government also established the Headquarters for Earthquake Research Promotion as a direct system of accountability for government policies regarding earthquakes. Since 1880, the year of the establishment of the first Seismological Society in the world, the Japanese seismological community has experienced 4 big changes such as the Great Nobi Earthquake Disaster in 1891, the Great Kanto Earthquake Disaster in 1923, the Second World War, and this earthquake disaster. These histories are reviewed from the point of view of social activities in Japanese seismology. Finally, we will discuss achievement for the sake of the mitigation of earthquake disaster on the lessons learned from the history.

著者

加藤 研一 宮腰 勝義 武村 雅之 井上 大榮 上田 圭一 壇 一男

出版者

JAPAN ASSOCIATION FOR EARTHQUAKE ENGINEERING

雑誌

日本地震工学会論文集 (ISSN:18846246)

巻号頁・発行日

vol.4, no.4, pp.46-86, 2004 (Released:2010-08-12)

参考文献数

125

被引用文献数

3 8

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内陸地殻内で発生する地震を対象として、既存の活断層図等の文献による調査、空中写真判読によるリニアメント調査、現地における地表踏査等の詳細な地質学的調査によっても、震源位置と地震規模を前もって特定できない地震を「震源を事前に特定できない地震」と定義し、その地震動レベルを震源近傍の硬質地盤上の強震記録を用いて設定した。検討対象は、日本およびカリフォルニアで発生した計41 の内陸地殻内地震である。地質学的調査による地震の分類を行い、9 地震12 地点の計15 記録 (30 水平成分) の強震記録を、震源を事前に特定できない地震の上限レベルの検討に用いた。Vs=700m/s 相当の岩盤上における水平方向の地震動の上限レベルとして、最大加速度値450 cm/s/s、加速度応答値1200cm/s/s、速度応答値100 cm/s が得られた。

著者

諸井 孝文 武村 雅之

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.52, no.1, pp.11-24, 1999-06-30 (Released:2010-03-11)

参考文献数

37

被引用文献数

1 7

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The distribution of seismic intensity I=VII (very disastrous) for the 1995 Hyogoken-Nanbu earthquake was reported by the Japan Meteorological Agency (JMA). It was the first announcement since the seismic intensity in JMA scale had been revised in 1949 to include the highest class of I=VII. Originally the seismic intensity of I=VII was defined as “strong ground motion with collapse more than 30% of wooden houses”, which was based on destructive damage at the 1948 Fukui earthquake. During the last half century, aseismic design of wooden houses has progressed especially due to the popularization of the standard building code published in 1950. Recent cities like Kobe include various kinds of buildings in seismic performance from modern earthquake-resisting structures to old and vulnerable residences. Therefore the seismic intensity of I=VII should be recognized as “with collapse more than 30% of less aseismic wooden houses such as those built before 1950”. From these points, it must be confirmed whether the increase of the seismic performance of buildings was taken into account in the reported distribution of I=VII. First we review the term of “collapse of houses”. Then relationship between the collapse rate of houses and the overturning acceleration of tombstones is investigated and analyzed using damage data obtained from the 1995 Hyogoken-Nanbu earthquake. The analysis result and its comparison to the relationships for past earthquakes show that the average of the seismic performance has increased by 40-60% from 1948 to 1995, and that the collapse rate of 10% at the Hyogoken-Nanbu earthquake corresponds to that of 30% at the Fukui earthquake for the same overturning acceleration. Comparing the reported distribution of I=VII to the area with collapse more than 10%, historical continuity of the seismic intensity in JMA scale is discussed.

著者

武村雅之 北原糸子監修

出版者

東京防災救急協会

巻号頁・発行日

2013

著者

武村 雅之 野澤 貴 池浦 友則

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.52, no.2, pp.317-333, 1999-10-20 (Released:2010-03-11)

参考文献数

30

被引用文献数

2

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Nozawa et al. (1995) proposed a source model with two big subevents of the same seismic moment for the 1923 Kanto earthquake (M=7.9), through the simulation of the records by the Imamura-type strong motion seismograph (displacementmeter) at Gifu observatory. This model was named Model I in the present study. The first subevent of Model I is located under the Odawara city, having a fault plane with the strike of N290°E and the rake angle of 162°. This fault has much strike slip component, which is consistent with the focal mechanism solution by KANAMORI (1971). However, the direction of the strike is not compatible with the trench axis of the Sagami trough. The second subevent occurring 12s after the first subevent is located under the Miura Peninsula. The fault of the second subevent, having much dip slip component, well explains the geodetic data. Recently, the seismograms by the Imamura-type strong motion seismographs at Sendai (Mukaiyama) observatory and Yamagata observatory were examined and the instrumental responses of the seismographs were revealed. Crustal structure from source to stations was estimated in the present study so as to explain the observed Love and Rayleigh waves at Sendai (JMA) and Yamagata observatories from the recent events occurring near the focal region of the 1923 Kanto earthquake. However, Model I failed to explain the records of the 1923 Kanto earthquake at Sendai (Mukaiyama) and Yamagata observatories, using the obtained crustal structure. Then, we revised Model I to explain these records, in consideration of the newly determined focal mechanism solution by Lallemant et al.. (1996) and iso-depth contour of the upper boundary of the Philippine Sea plate by Ishida (1992). The first subevent of the revised model (Model R) has a fault plane with the strike of N321°E and the rake angle of 128°, and the twice of seismic moment of the second subevent. The direction of the fault strike of the first subevent is parallel to the trench axis of the Sagami trough, while the fault plane of the second subevent is the same as Model I. Model R succeeded in explaining not only the records at Sendai (Mukaiyama) and Yamagata observatories but also those at Gifu observatory in the period range from 2 to 20s. This shows the fault model, being in agreement with the geometry of subduction zone along the Sagami trough, is better to explain the seismic records observed in Japan.

著者

武村 雅之 諸井 孝文

出版者

公益社団法人 日本地震工学会

雑誌

日本地震工学会論文集 (ISSN:18846246)

巻号頁・発行日

vol.2, no.2, pp.55-73, 2002 (Released:2010-08-12)

参考文献数

21

被引用文献数

3 3

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1923 年関東地震における埼玉県の詳細な震度分布を推定するために、当時の地質調査所の被害報告書に書かれている木造住家の全潰数、半潰数、地盤の液状化発生地点などを整理しデータベース化した。地調の報告書には、市町村単位の被害集計よりさらに細かい大字毎の集計値が記載されており、それらを市町村単位の集計値に加えて震度7に達する地域を特定することができた。震度の評価結果が地下構造に密接に関連していることが明らかになった。過去に埼玉県が実施した地震危険度評価の結果とも比較し、今後の地震危険度評価のあり方にも言及する。

著者

野澤 貴 武村 雅之 池浦 友則 山中 浩明

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.48, no.3, pp.331-340, 1995-11-25 (Released:2010-03-11)

参考文献数

30

被引用文献数

1

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Records observed at Gifu observatory by an Imamura's type strong motion seismograph are one of the most useful records in Japan to investigate a source process of the 1923 Kanto earthquake (M=7.9). It is because amplitudes of the records are not saturated in EW and UD components, instrumental response of the seismograph has been clarified, and many records due to recent events occurred near the focal region of the Kanto earthquake have been obtained by more accurate seismographs at the same site. In the present study, a source process of the 1923 Kanto earthquake is elucidated through a simulation of the records using the normal mode theory in the period range from 2 to 20s. First, a crustal structure from the source to the station is estimated so as to explain dispersive characteristics of Love waves observed at Gifu observatory for the recent events, and their records are simulated to confirm a validity of the estimated crustal structure. Secondly, the records from the Kanto earthquake are simulated using the obtained crustal structure to deduce the source process of this event. According to KANAMORI (1971), a macroscopic faulting is a reverse right-lateral fault on a plane dipping 34° towards N20°E, whose slip has much strike component. If two big subevents with the same focal mechanism obtained by KANAMORI (1971) and with a time interval of about 12s are assumed on the fault plane, the observed records can be well explained. The first subevent is located under the Odawara city and the second one under the Miura Peninsula. The focal depth of the second event is 15 to 35km being deeper than that of the first event, which is 5 to 25km in depth. The seismic moments and the rise time are assumed 2.5×1027 dyne-cm and 5s for both the events respectively. On the other hand, if the focal mechanism of the second event is dip slip type, the observed records can be also explained well, even though the focal depth of the second subevent is the same as that of the first one. This model is consistent with a slip distribution on the fault plane obtained from geodetic data.

著者

武村 雅之 諸井 孝文

出版者

公益社団法人 日本地震工学会

雑誌

日本地震工学会論文集 (ISSN:18846246)

巻号頁・発行日

vol.1, no.1, pp.1-26, 2001 (Released:2010-08-12)

参考文献数

27

被引用文献数

6

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1923年関東地震における千葉県の詳細な震度分布を推定するために、当時の地質調査所の被害報告書に書かれている木造住家の全潰数、半潰数、墓石の転倒率などを整理しデータベース化した。地調の報告書には、市町村単位の被害集計よりさらに細かい大字毎の集計値が記載されており、それらを用いて500箇所以上で震度を評価することができた。千葉県は、東京都、神奈川県とともに最も大きな被害を出した地域の1つであり、県内は大きな地震動に襲われた。ここでまとめたデータベースならびに詳細震度分布は、今後の千葉県における地震動予測に役立つことが期待される。

著者

武村 雅之 諸井 孝文

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.53, no.3, pp.285-302, 2001-03-25 (Released:2010-03-11)

参考文献数

28

被引用文献数

4

著者

武村 雅之 野澤 貴

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.3, pp.375-387, 1996-11-23 (Released:2010-03-11)

参考文献数

13

被引用文献数

3

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Seismograms from the 1923 Kanto earthquake (M=7.9) and its aftershocks at the Yamagata observatory of JMA (The Japan Meteorological Agency) in Tohoku district, Japan, are examined. They were recorded by the Imamura-type strong motion seismograph. Horizontal-component records from the main shock and the 1924 Tanzawa earthquake (M=7.3), one of the largest aftershocks, are digitized and the instrumental characteristics of the seismographs are examined. Natural period To and damping ratio v of the instrument are evaluated to be 4.5s and 1.5 for both the NS and EW components from the free oscillation records and documents for the results of testing the instrumental response. The maximum displacement in EW component of 11.2cm is obtained for the main shock in the period range from 2 to 20s, after the instrument correction.On the other hand, uncertainties of the instrumental characteristics remain for the seismograms from the 1923 Kanto earthquake observed at the Mukaiyama observatory of the Tohoku Imperial University in Sendai, [TAKEMURA et al. (1995)]. The Sendai city is located about 40km east from the Yamagata city. The epicentral distance and azimuth of the Mukaiyama observatory is not so different from those of the Yamagata observatory for the 1923 Kanto earthquake. It is found that the displacement records at Sendai and Yamagata have mostly the same amplitude for the recent moderately large earthquakes with almost the same location of epicenter as the 1923 Kanto earthquake. All the records were observed by the strong motion displacement seismographs of To=6s and v=8 both at the Yamagata observatory and at the Sendai district meteorological observatory of JMA. This fact indicates that the displacement at the Mukaiyama observatory in Sendai ought to show almost the same amplitude as one at the Yamagata observatory during the 1923 Kanto earthquake. Then, we redetermined To of the instrument at Mukaiyama observatory so that the amplitude of the displacement after the instrument correction is the same as that at the Yamagata observatory. Redetermined To is 5s in EW component, being meaningfully longer than the results estimated by TAKEMURA et al. (1995).

著者

野澤 貴 武村 雅之

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.50, no.1, pp.11-20, 1997-05-28 (Released:2010-03-11)

参考文献数

12

被引用文献数

1

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Records observed at the Takada observatory by an Imamura's type strong motion seismograph are useful in Japan to investigate a source process of the 1923 Kanto earthquake (M=7.9). Ground motion in the vertical component is completely recorded to the end. Those in horizontal components are also recorded to the end, though the amplitudes of them are saturated in the midst of the records. The instrumental response of the seismograph has been already clarified by TAKEMURA and NOZAWA (1996), and many records from the recent earthquakes occurring near the focal region of the Kanto earthquake are also obtained at the same site with modern instruments. First, a crustal structure model from the source to the station is established so as to explain the dispersion characteristics of Love-waves observed for the recent earthquakes, and their records are simulated by the normal mode theory using the obtained structure to confirm its validity. Secondly, the records from the Kanto earthquake are reproduced using the same structure model. NOZAWA et al. (1995) proposed the two possible source models for the Kanto earthquake through the simulation of the records at the Gifu observatory. Two big subevents with a time interval of about 12s are assumed on the fault plane in both the models, while the focal mechanism and the focal depth of the second subevent are different between these models. It is found that these models similarly explain the records at the Takada observatory from the Kanto earthquake. The maximum displacements of the reproduced horizontal ground motions are estimated about 20cm in NS component. and about 10cm in EW component. These results are consistent with the fact that the amplitudes of the records in NS component are strongly saturated compared with those in EW component.

著者

小山 順二 武村 雅之

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.36, no.2, pp.255-257, 1983-06-25 (Released:2010-03-11)

参考文献数

10

著者

小山 順二 武村 雅之 鈴木 次郎

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.33, no.2, pp.187-198, 1980-06-25 (Released:2010-03-11)

参考文献数

21

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A simple method is developed to determine seismic moments of earthquakes by using tabulated data in usual seismological bulletins. The method is qualified through the criteria such as simplicity of calculations, coverage of wide magnitude range, and insensitivity of the instrumental response: At first, characteristic period Tc of each earthquake is defined as the average value of apparent periods of wavelets which give maximum amplitudes of ground displacement at epicentral distances between 200 and 700km. Secondly, amplitude information is taken into consideration, making a product of maximum amplitude, its period and epicentral distance. Seismic-moment factor Me for a given earthquake is defined at the characteristic period Tc as the average value of those products evaluated from horizontal components at stations within epicentral distance range from 200 to 400km. The narrow range of epicentral distance in evaluating Me is taken so as to reduce the uncertainty due to seismic-energy attenuation into a permissible range and to be able to obtain equal number of observations for small earthquakes to that for large ones. The relation between the seismic-moment factors and characteristic periods for 163 intraplate earthquakes in Japan from 1926 to 1977 clearly demonstrates that Me is proportional to the cube of Tc. A scaling model of earthquakes that satisfies the empirical relations among surface-wave magnitude, JMA magnitude, and body-wave magnitude facilitates the estimate of static seismic-moments from calculated Me's. The seismic moments of 16 earthquakes determined by conventional analyses from near- and/or far-field observations are consistent with static seismic-moments thus estimated. This shows the potential in practice of the present method especially in routine processing of seismic data.

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.2012, no.37, pp.39-44, 2012-09-30 (Released:2016-03-16)

著者

中井 春香 武村 雅之

出版者

公益社団法人 日本地震工学会

雑誌

日本地震工学会論文集 (ISSN:18846246)

巻号頁・発行日

vol.15, no.7, pp.7_220-7_229, 2015 (Released:2015-12-25)

参考文献数

14

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1945年1月13日に発生した三河地震の特徴としては、東南海地震の約1か月後に発生した地震であること、戦時中であったこと、そして家屋喪失数に対して死者数が多い地震であることがあげられる。飯田(1985)のデータにおける三河地震の被害として一般的に用いられている数値は調査データの最大値の総括であり、市町村単位とする内訳に戻れないことが判明した。このため、1945年1月14日の愛知県警備課による統一的なデータも用いながら、各市町村のデータを算出し震度分布図をGISを用いて作成した。その結果、沖積低地である岡崎平野や矢作川流域では被害が大きく、幡豆山地などの丘陵地に属する地域は被害が小さかった。また、地盤による震度や被害の影響は、東南海地震と類似していたことがわかった。一方、断層のごく近傍では、全潰家屋の割に死者数が特に多く発生している傾向もみられ、断層近傍特有の被害にも注目する必要があるものと考えられた。

著者

武村 雅之

出版者

一般社団法人 日本物理学会

雑誌

日本物理学会誌 (ISSN:00290181)

巻号頁・発行日

vol.50, no.9, pp.730-735, 1995-09-05 (Released:2008-04-14)

参考文献数

18

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兵庫県南部地震は阪神地域を中心に大きな被害をもたらした.阪神地域での被害調査結果を分析すると,被害は地域的に集中しており,被害の大きい地域とそうでない地域とがはっきりと別れている.このような被害分布の特徴をまとめるとともに,密接に関連する地震動強さの地域性について検討する.検討は被害集中域と震源断層との関係,および地盤構造との関係の二つの側面から行う.その結果,阪神地域の被害分布は震源断層だけでは説明できず,地盤構造の地域性を考慮する必要があることが分かった.