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Hokkaido University Collection of Scholarly and Academic Papers (135.521 recursos)

HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.

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Mostrando recursos 1 - 20 de 26

  1. 目次(英語)・奥付・裏表紙


  2. 表紙・目次(日本語)


  3. 十勝岳62-Ⅱ火口周辺の3次元比抵抗構造

    山谷, 祐介; 橋本, 武志; 茂木, 透; 村上, 亮; 岡崎, 紀俊; 吉本, 充宏; 伏谷, 祐二; 橋本, 政樹; 山本, 輝明; 西村, 三治; 有田, 真; 的場, 敦史; 土屋, 遼平
    Tokachidake Volcano is an active volcano, situated at the SW end of the Daisetsu-Tokachi volcanic chain in the central Hokkaido, Japan. We performed the AMT resistivity survey around the 62 -II crater at the volcano in order to realize the hydrothermal zone, focusing on the recent activity of the crustal inflation and demagnetization beneath the crater. The measured AMT data suggested the three-dimensional structure beneath the study area. Prior to the resistivity modeling, we estimated an effect due to a steep topography in the study area. This estimation clearly showed a strong effect to the apparent resistivity, impedance phase and...

  4. 十勝岳の全磁力変化と蓄熱過程(2008 - 2009年)

    橋本, 武志; 西村, 三治; 有田, 真; 山本, 輝明; 小木曽, 仁; 重野, 伸昭; 岡崎, 紀俊; 茂木, 透
    We report the recent results of geomagnetic repeat surveys aiming for the detection of subsurface thermal changes at Tokachidake volcano, central Hokkaido, northern Japan. We conducted the first survey in October, 2008. The same pegs and marks were reoccupied in July and September, 2009. During this period a clear dipolar pattern of magnetic changes was detected around the 62-II crater, the present main vent of Tokachidake. This change is quite consistent with the pattern due to a demagnetized sphere placed at a depth of 150 m(1,600 m a.s.l.)beneath the 62-II crater. The change of magnetic moment amounts to 1 -...

  5. ウェーブレット変換の地震エコー記録への適用とその効果

    山下, 晴之; 渡邉, 朋典; 森谷, 武男; 茂木, 透
    Anomalous VHF-band radio-wave propagation beyond the line of sight prior to earthquakes has been observed since 2002 in Hokkaido area. These records of the propagation have been collected as variations of electric field, and they include not only EQ-echoes which are shown as anomalous upward rapid drifts associated with an impending earthquake but also other transient signals and high frequency noises. It is not appropriate to apply the Fourier transform to such rapid variations because transient local changes in time domain data are transformed into the overall feature in frequency domain. In contrast, the wavelet transform suppresses this influence of...

  6. 体積歪変化量から推定した伊豆東部火山群のマグマ貫入量と火山活動評価の試み

    宮村, 淳一; 上野, 寛; 横田, 崇
    Many dyke intrusion events have repeatedly occurred at Izu-Tobu Volcanoes since 1978.In order to evaluate volcanic activity of Izu-Tobu Volcanoes and to forecast the volcanic eruption,we investigate relationship between the amount of intrusive magma estimated from dyke parameters obtained by previous studies and the amount of volumetric strain change observed at Higashi-Izu.As a result,we find that there is an obvious correlation between the volume of dyke intrusions and the maximum amount of volumetric strain changes in 24 hours. In addition,we notice that large magma intrusion causes a remarkable seismic activity more than expected from the amount of volumetric strain changes....

  7. 2007年中越沖地震の地震動特性

    土方, 勝一郎
    Strong motion records of 2007 Niigata-ken Chuetsu-oki earthquake were examined in order to evaluate ground motion characteristics of the earthquake. Ground motion observed at Kashiwazaki Kariwa Nuclear Power Plant site were significantly larger than the response spectra evaluated on the basis of Noda et al(. 2002), and the level of the ground motion observed at Arahama area(unit 1 - 4 side)was approximately twice as large as that at Ominato area(unit 5 - 7 side). Observation records of the offshore events other than the eathquake were also larger than the response spectra based on Noda et al(. 2002), whereas records of...

  8. 2003年十勝沖地震の最大余震による特異な地震動特性

    前田, 宜浩; 高井, 伸雄; 笹谷, 努
    The largest aftershock(Mw 7.3)of the 2003 Tokachi-oki earthquake(Mw 8.3)generates larger peak ground acceleration(PGA)values than the main shock in the western side of the epicenters despite their magnitude difference. We study the features of strong ground motions from the largest aftershock in detail using PGA values. Spatial distribution maps of PGA ratio between the largest aftershock and adjacent earthquake shows obvious azimuth dependency compared with the other earthquake pairs occurring around Japan. Attenuation relationship of the largest aftershock shows a large azimuth-dependent scattering at distances from 200 to 300 km compared with three smaller earthquakes occurring around the largest aftershock. Because...

  9. 強震動の測定小史における機動観測

    工藤, 一嘉
    A historical sketch of mobile strong-motion observations is illustrated with a brief review of standard measurements of strong earthquake ground motion in Japan. A mobile strong-motion observation has generally been carried out for aftershocks and/or earthquake swarms as initiated by Kanai et al.(1966). Great advantages of mobile array observation by organizing plural groups were found in the aftershocks of two large Hokkaido earthquakes of 1993, Hokkaido-Nansei oki, and Kushiro oki. A significance of mobile strong-motion observation is also described. A potable strong-motion instrument is a key factor for mobile observation and recent developments by continuous recordings will give us new-findings.

  10. 2003年十勝沖地震の地震記録に見られる 地盤の非線形応答に関する研究

    三輪田, 吾郎; 高井, 伸雄; 清水, 学; 笹谷, 努; 前田, 宜浩; 山本, 明夫
    Nonlinear site response was observed at TKCH 07 in Toyokoro and HKD 109 in Urakawa during the mainshock(Mj 8.0)and the largest aftershock(Mj 7.1)of the 2003 Tokachi-oki Earthqua ke. At TKCH 07, peak ground acceleration(PGA)was smaller than PGA at the other strong motion station in Toyokoro. At HKD 109, the accelerogram shows a characteristic spiky waveform. Due to this spiky wave, large PGA was observed compared to the other stations in Urakawa, although PGA at HKD 109 was smaller than PGA at JMA Urakawa station during the main shock and smaller aftershocks.

  11. 横等方的媒質における理論地震記象への非弾性減衰の導入

    竹中, 博士; 中村, 武史
    We propose an effective scheme for incorporating anelastic attenuation in synthetic seismograms for transversely isotropic media, where the scheme uses only two kinds of quality factors Q: QP and QS instead of five kinds of Q corresponding to five independent elastic constants. It is a straightforward extension of the scheme for isotropic media in the reflectivity method. We implement our scheme in a reflectivity code for transversely isotropic media, and show some numerical examples to illustrate feasibility of the scheme.

  12. 地震計鉛直アレー記録の相分解法の改良

    吉田, 邦一
    I modify a vertical array analysis method that decomposes complex seismograms into body and surface wave time histories that have been proposed by Yoshida and Sasatani(2008). In the previous study, P, S and surface waves at the surface were decomposed by a least-squares method without any weighting. In the present study, the data are weighted by using the maximum amplitude of each spectrum of seismograms. I carried out a numerical test of this method with synthetic vertical array records consisting of vertically incident plane P and S waves and laterally incident plane Love and Rayleigh waves. P, S, Love, and...

  13. 石狩平野北西部における微動アレー探査

    吉田, 邦一; 笹谷, 努; 前田, 宜浩; 高井, 伸雄; 三輪田, 吾郎; 大畑, 大志郎; Prasad, Dhakal Yadab; 鏡味, 洋史; Fat-Helbary, Raafat El-Shafei
    S-wave velocity structures were explored in the northwestern part of Ishikari plain from microtremor array measurements. We measured microtremors using seismometer arrays at 3 sites on 4 days during May - July 2005. Phase velocities in a frequency range of 0.22 - 4.32 Hz were estimated using SPAC(SPatial AutoCorrelation)analysis of the microtremor records. The S-wave velocity structures were obtained by the inversion from the phase velocities using a genetic algorithm technique. The inverted S-wave velocity structures obtained from the microtremor array surveys in the present and previous studies indicate that the S-wave velocities of a geologic layer clearly depend on...

  14. 近年の強震動記録に基づく計測震度の距離減衰式

    森川, 信之; 神野, 達夫; 成田, 章; 藤原, 広行; 福島, 美光
    We obtain a new attenuation distance-relation of seismic intensity for Japan using the strongmotion data-base constructed by Kanno et al.(2006). We also obtain additional correction terms corresponding to the site amplification, anomalous seismic intensity and event type(plate-boundary or intra-slab). Although we used strong-motion data until the 2003 Tokachi-oki earthquake, the attenuation relation agrees to observed records during recent large earthquakes.

  15. 経験的グリーン関数法による2009年8月11日駿河湾の地震(MJMA 6.5)の震源モデルの推定と強震動シミュレーション

    浅野, 公之; 岩田, 知孝
    On August 11, 2009, an intraplate earthquake (MJMA 6.5) occurred within the subducting Philippine Sea slab beneath Suruga Bay at a depth of 23 km. The source model composed of two strong motion generation areas(SMGA)has been estimated by the broadband strong motion simulation using the empirical Green's function method in the frequency range between 0.3 Hz and 10 Hz. The stress drop of each SMGA is estimated to be 35.7 MPa and 27.5 MPa. The rupture of SMGA 1 on the southeast dipping fault plane mainly propagated southwestward, and that of SMGA 2 on the northeast dipping fault plane propagated...

  16. 強震動予測のためのスラブ内地震の特性化震源モデルの構築

    岩田, 知孝; 浅野, 公之
    We study characterized source model for the strong motion prediction of intraslab earthquakes in the same manner as crustal earthquakes (Somerville et al., 1999) and interplate earthquakes (Murotani et al., 2009). We characterized the heterogeneous slip distributions of 11 events with MW 6.6-8.3 and determined rupture area(S), total asperity area(Sa), and average slip(D)with following the procedure proposed by Somerville et al.(1999). Assuming power of 2/3 dependency of S and Sa on seismic moment and that of 1/3 for D, we got the empirical relationships as follows, S(km2 )= 6.57×10-11×M0 2/3(Nm) Sa(km2 )= 1.04×10-11×M0 2/3(Nm) D(cm)= 2.25×10-5×M0 2/3(Nm) The stress parameters...

  17. 内陸地殻内の長大断層で発生する地震に関するスケーリング則

    松島, 信一; 室谷, 智子; 吾妻, 崇; 入倉, 孝次郎; 北川, 貞之
    Since 2005, The Headquarters for Earthquake Research Promotion(HERP)has been publishing National Seismic Hazard Maps for Japan to provide useful information for disaster prevention countermeasures for the country and local public agencies, as well as promote public awareness of disaster prevention of earthquakes. In the course of making the year 2009 version of the map, which is the commemorate of the tenth anniversary of the settlement of the Comprehensive Basic Policy, the methods to evaluate magnitude of earthquakes, to predict strong ground motion, and to construct underground structure were investigated in the Earthquake Research Committee and its subcommittees. Within approximately 100...

  18. 1923年関東地震の再現をふまえた強震動研究とデータ分析に関する一考察

    諸井, 孝文; 武村, 雅之
    Datasets of structural damage and regional damage due to past earthquakes are not only useful to know the actual state of each event but also effective for strong ground motion predictions and damage mitigations of future earthquakes. In this paper, several considerations are illustrated concerning strong ground motion research and data processing analysis. Especially, the activity to make research results contribute to society is discussed based on three examples of earthquake damage data analysis. The examples shown here describe that the well known notion in general, what is called common knowledge, does not necessarily have high reliability, and that the...

  19. 強震動研究と建築構造物の入力地震動評価

    加藤, 研一
    The seismic provisions of the Building Standard Law of Japan were revised in 2000 towards a performance-based design code. This is a drastic revision since the input ground motions are defined on the outcropped engineering bedrock in terms of acceleration response spectra. In addition, the revised seismic design code for structures taller than 60 m accepts to use site-specific design ground motions due to scenario earthquakes. Recently, extremely large acceleration more than 1 g were often observed in near fault regions of crustal earthquakes. The amplitude level of those records exceeds the above-mentioned design ground motions on the outcropped engineering...

  20. 観測記録に基づいたスラブ内地震の短周期レベル

    池田, 孝
    Acceleration source spectra of three intra-slab earthquakes which occurred recently were evaluated by eliminating the effects of propagation path and site characteristics from observation records. Short-period spectral level A were evaluated from the acceleration source spectra, and stress parameters Ao were calculated from A and seismic moment M0. The relationship between Ao, focal mechanism, regionality, location, M0, and focal depth were examined. Ao of intra-slab earthquakes was not much affected by focal mechanism, regionality in the Pacific plate. The effect of location and focal depth to Ao is not clear, but Ao is not dependent on focal depth for medium...

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