Researcher Database

YOSHIZAWA Kazunori
Faculty of Science Earth and Planetary Sciences Earth and Planetary Dynamics
Associate Professor

Researcher Profile and Settings

Affiliation

  • Faculty of Science Earth and Planetary Sciences Earth and Planetary Dynamics

Job Title

    Associate Professor

Degree

  • M.Sc., Hiroshima University

URL

Research Interests

  • tomography   anisotropy   surface waves   lithosphere   asthenosphere   Physics of Earth's Interior   seismology   Earth Structure   Seismic Tomography   

Research Areas

  • Earth and planetary science / Solid earth and planetary physics / seismology

Academic & Professional Experience

  • 2007/05 - Today    Hokkaido UniversityFaculty of ScienceAssociate Professor
  • 2007/04 - 2007/04    Hokkaido UniversityFaculty of ScienceAssistant Professor
  • 2006/04 - 2007/03    Hokkaido UniversityFaculty of ScienceInstructor
  • 2002/04 - 2006/03    Hokkaido UniversityGraduate School of ScienceInstructor
  • 2018/10 - 2018/10    Tohoku UniversityGraduate School of SciencePart-time Lecturer
  • 2016/04 - Today    NIEDVisiting Researcher
  • 2015/04 - 2016/03    The University of TokyoEarthquake Research InstituteVisiting Associate Professor
  • 2015/08 - 2015/08    Kobe UniversityGraduate School of SciencePart-time Lecturer
  • 2012/04 - 2013/03    The University of TokyoEarthquake Research InstituteVisiting Associate Professor
  • 2011/06 - 2011/07    The Australian National UniversityResearch School of Earth SciencesVisiting Fellow
  • 2008/02 - 2010/02    Columbia UniversityLamont-Doherty Earth ObservatoryVisiting Scientist
  • 1998/04 - 1998/12    JSPS Research Fellow (DC1)
  • [Other Visiting Positions]

Education

  • 1999/03 - 2002/03  Australian National University  Research School of Earth Sciences (Ph.D. course)
  • 1996/04 - 1998/03  Hiroshima University  Graduate School of Science  Department of Earth and Planetary Systems Science (Master course)
  • 1993/04 - 1996/03  Hiroshima University  Faculty of Science  Department of Earth and Planetary Systems Science (Skipped)

Association Memberships

  • Seismological Society of Japan   Japan Geosciences Union   American Geophysical Union   Seismological Society of America   Society of Exploration Geophysicists   

Research Activities

Published Papers

Books etc

  • Physics of the Earth
    Honda S., Iwamori H., Utada H., Okubo S., Kurita K., Tsuchiya T., Nakai S., Hiraga T., Miyatake T. and Yoshizawa K.  (Chap 16-17)
    Asakura Publishing Co. Ltd. 2013/07 Joint Translation

Conference Activities & Talks

  • Fine-scale random heterogeneity and apparent radial anisotropy of S-waves in the lithosphere and asthenosphere   [Not invited]
    YOSHIZAWA Kazunori
    Seismological Society of Japan 2018 Fall Meeting  2018/10
  • Mapping the upper mantle beneath North American continent with joint inversion of surface-wave phase and amplitude  [Not invited]
    K. Yoshizawa and K. Hamada
    American Geophysical Union 2017 Fall Meeting  2017/12
  • Seismic Tomography and Tectonics  [Invited]
    YOSHIZAWA Kazunori
    Summer School of Seismology  2017/09
  • A seismological constraint on the asthenosphere: mapping radial anisotropy with multi-mode surface waves  [Invited]
    YOSHIZAWA Kazunori
    JpGU-AGU Joint Meeting 2017  2017/05
  • Lithosphere-asthenosphere transition, mid-lithosphere discontinuity and radial anisotropy from multi-mode surface wave tomography  [Invited]
    YOSHIZAWA Kazunori
    American Geophysical Union 2015 Fall Meeting  2015/12
  • Mapping the upper mantle with multi-mode surface waves: Lithosphere-ashtenosphere transition and radial anisotropy  [Invited]
    YOSHIZAWA Kazunori
    The 14th International Symposium on Study of the Earth's Deep Interior  2014/08  the Shonan Village Center, Kanagawa, Japan
  • The Lithosphere-Asthenosphere Transition and Radial Anisotropy Beneath Australian Continent  [Invited]
    YOSHIZAWA Kazunori
    Asia and Oceania Geoscieces Society 11th Annual Meeting  2014/07  Royton Sapporo Hotel, Japan
  • Radially anisotropic shear wave model of North America from multi- mode surface tomography using USArray  [Invited]
    YOSHIZAWA Kazunori
    JpGU Meeting 2010  2010/05

MISC

  • Junji Koyama, Motohiro Tsuzuki, Kiyoshi Yomogida, Kazunori Yoshizawa  Journal of the Hokkaido University, Faculty of Science, Series VII: Geophysics  129  -146  2013/12   [Not refereed] [Not invited]
  • Kazunori Yoshizawa  Journal of the Hokkaido University, Faculty of Science, Series VII: Geophysics  39  -48  2008/12   [Not refereed] [Not invited]  
    Seismic waves generated by a nuclear test carried out by North Korea on October 9, 2006 were observed throughout the Japanese islands. Clear arrivals of Pn waves, which traveled below the Moho discontinuity underneath the Japan Sea, were recorded by the Japanese broad-band seismic network, F-net, deployed by National Research Institute for Earth Science and Disaster Prevention (NIED). We analyzed the waveforms of the nuclear event observed at F-net stations as well as some global seismic stations in East Asia. Apparent path-average velocity of Pn waves and their maximum amplitudes are estimated from vertical component seismograms of the F-net stations. We found conspicuous regional variations of apparent path-average velocity and maximum amplitude. For example, fast apparent velocity and larger amplitude are observed in the paths across the Japan basin in the northern Japan Sea, whereas slow velocity as well as relatively smaller amplitudes are found in the path to stations in Kyushu. Such regional variability of Pn waves is likely to make it difficult to estimate source parameters for this small-scale explosive event in the Korean Peninsula, only using the Japanese seismic network. These results suggest the necessity of a precise three-dimensional seismic model of the Japan Sea to utilize Japanese seismic network data for analysis of regional seismic waves that propagate along a variety of paths in the Japan Sea.
  • Kazunori Yoshizawa  Journal of the Hokkaido University, Faculty of Science, Series VII: Geophysics  15  -21  2006/12   [Not refereed] [Not invited]  
    The great Sumatra earthquake on December 26, 2004, which devastated the coastal areas of the Indian Ocean by the subsequent tsunami, generated tremendous numbers of surface-wave trains which traveled around the globe for many times. We analyze vertical-component seismograms of the event recorded by the F-net broadband seismic network in Japan, which has been deployed and maintained by NIED (National Research Institute for Earth Science and Disaster Prevention, Japan). By applying a band-pass filter between 3 and 5 mHz, we extract the long-period Airy phase of the fundamental-mode Rayleigh wave. The long-period records display a magnificent series of multi-orbit Rayleigh wave trains that have circumnavigated the Earth for more than 6 times; i.e., we are able to observe clear signals up to R13-R14 phases. Although much later arrival phases than R14 become less visible mainly due to lateral heterogeneities in the Earth as well as dispersions of surface waves, we are still able to detect some small signals up to R18.
  • Seismology and Physics of the Earth's Interior
    Yoshizawa K., Yomogida K. and Tsuboi S.  IUGG report "Geosciences: The Future"  11  -21  2003/07   [Refereed] [Invited]  Meeting report etc.
  • Societal Impact
    Yoshizawa K.  IUGG report "Geosciences: The Future"  95  -100  2003/07   [Refereed] [Invited]  Meeting report etc.
  • K. Yoshizawa, B. L N Kennett  Geophysical Journal International  149-  118  -133  2002/05   [Not refereed] [Not invited]  
    A new technique for multimode dispersion measurement has been developed by employing fully non-linear waveform inversion for a path-specific 1-D profile using a neighbourhood algorithm (NA). One-dimensional models derived from waveform inversion are quite sensitive to the model parametrization and the reference model used to start the inversion. With different approaches to the parametrization of the shear wave speed profile, we can find models with significant differences in velocity variation with depth, which provide similar levels of fit to the observed waveforms. Although the models differ, the calculated phase dispersion for the first few modes of the surface waves are very close indeed. We therefore regard the 1-D models derived from the multimode waveform inversion as an implicit description of the path-specific dispersion for each of the modes. The inversion procedure using NA samples a substantial number of models and we select the 1-D wave speed model that achieves minimum misfit. Phase speeds for each for each mode branch are then calculated from the model parameters with the minimum misfit. Because we use the 1-D models as a summary of the average multimode dispersion along the path, we do not need to make assumptions concerning the nature of anisotropy. We can employ simple isotropic models and the method can be applied to both Rayleigh and Love waves independently. The new method is applied to sets of paths in the Australian region and provides stable measurements of multimode dispersion from a single seismogram. The multimode phase speeds measured using the NA inversion can be used to retrieve phase velocity maps as a function of frequency for higher-mode branches as well as the fundamental mode, which will be crucial constraints on 3-D Earth models.

Awards & Honors

  • 2007/05   Seismological Society of Japan   Young Investigator Award
       Prize from Japan society, conference, symposium, etc.  
    Winner: Kazunori Yoshizawa
  • 2001/12   American Geophysical Union   Outstanding Student Paper Award
       「Surface Wave Tomography: A Three-Stage Approach」   Prize from international Society, conference, symposium, etc.

Research Grants & Projects

  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(特定領域研究)
    Date (from‐to) : 2004 -2008 
    Author : Minoru KASAHARA
     
    北海道大学
  • Structure and Dynamics of Earth's Interior using Seismic Tomography
    The Other Research Programs
    Date (from‐to) : 1999 -2004
  • Effects of Finite Frequency on Seismic Wave Propagation
    The Other Research Programs
    Date (from‐to) : 1999 -2004
  • Global tomography Incorporating Surface Wave Finite Frequency Effects
    The Other Research Programs
  • Development of a simultaneous inversion technique of body and surface waves
    The Other Research Programs

Educational Activities

Teaching Experience

  • Advanced Seismology
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 理学院
    キーワード : 地震データ解析,地震波動伝播,地球内部構造
  • Special Lecture on Natural History Science I
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 理学院
    キーワード : 海洋重力波、地震波動伝搬、地震波干渉法
  • Laboratory Work in Earth and Planetary Sciences II
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 堆積物,堆積岩,堆積環境,水圏環境,古海洋,古気候,気象,天気図,統計解析,地震,地震波,震源
  • Seismology and Physical Volcanology I
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 弾性論,地震波伝播,地震,地球内部構造,震源
  • Seismology
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 弾性論,地震波伝播,地震,地球内部構造,震源

Committee Membership

  • 2006 - Today   Seismological Society of Japan   Board of Representatives
  • 2002   Seismological Society of Japan   A Local Liaison Committee   Seismological Society of Japan


Copyright c MEDIA FUSION Co.,Ltd. All rights reserved.