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Study of seasonal variation of groundwater and atmospheric loads : Possible influence on seismicity and astrometry

Research Project

Project/Area Number 15540413
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Solid earth and planetary physics
Research InstitutionHokkaido University (2004)
National Astronomical Observatory of Japan (2003)

Principal Investigator

HEKI Kosuke  Hokkaido University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (30280564)

Co-Investigator(Kenkyū-buntansha) 田村 良明  国立天文台, 地球回転研究系, 助手 (90150002)
Project Period (FY) 2003 – 2004
Project Status Completed (Fiscal Year 2004)
Budget Amount *help
¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2004: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2003: ¥800,000 (Direct Cost: ¥800,000)
Keywordsatmospheric load / snow load / ocean load / soil moisture / crustal deformation / seismicity / GPS / astrometry / 降水荷重 / 季節変動
Research Abstract

We quantitatively evaluated various factors governing the seasonal components in the position time series of the Japanese nationwide GPS network (GEONET). We found that seasonal changes of surface loads in the Japanese Islands are responsible for seasonal changes. Among them, the snow loads are several times as large as other kinds of loads. Atmospheric loads, groundwater loads (soil moisture and empoundment in reservoirs), non-tidal ocean loads were found to be of secondary importance. We estimated the seasonal changes of these loads using meteorological data and models, and calculated expected seasonal crustal deformation, compared them with actually observed deformations. We found that, in addition to these load changes, significant contributions come from the apparent changes associatedd with seasonal scale changes of unknown origin and atmospheric delay gradients. We established empirical seasonal change models considering all these factors, and the seasonal changes predicted by these models were consistent with actual GPS data. Seasonal components have been removed by an adaptive method, i.e. by estimating annual and biannual components using least-squares method in order to isolate transient crustal deformation signals. Our investigation showed that removal of seasonal components using our model based on a priori knowledge (non-adaptive correction) gives rise to as good results as the adaptive method. Our results were published in the book "State of the Planet" (AGU Geophysical Monograph Series Vol.150). We also calculated the Coulomb Failure Stress caused by such seasonal loads and found they have some influence on the inland seismicity in Japan. It has been known that there are more earthquakes in spring/summer than in fall/winter in snow covered regions, which is consistent with our prediction. This was reported as a paper in Earth Planet.Sci.Lett., and was introduced by major scientific journal s such as Nature and New Scientist.

Report

(3 results)
  • 2004 Annual Research Report   Final Research Report Summary
  • 2003 Annual Research Report
  • Research Products

    (10 results)

All 2005 2004 2003 Other

All Journal Article (6 results) Book (2 results) Publications (2 results)

  • [Journal Article] Secular, transient and seasonal crustal movements in Japan from a dense GPS array : implication for plate dynamics in convergent boundaries2005

    • Author(s)
      Heki, K.
    • Journal Title

      The Seismogenic Zone of Subduction Thrust Faults (edited by T.Dixon and C.Moore) (Columbia University Press) (In press)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Journal Article] Space geodetic observation of deep basal subduction erosion in NEJ2004

    • Author(s)
      Heki, K.
    • Journal Title

      Earth Planet.Sci.Lett. 219

      Pages: 13-20

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Annual Research Report 2004 Final Research Report Summary
  • [Journal Article] Dense GPS Array as a New Sensor of Seasonal Changes of Surface Loads2004

    • Author(s)
      Heki, K.
    • Journal Title

      A GU Geophys.Monograph "The State of the Planet" 150

      Pages: 177-196

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Journal Article] Dense GPS Array as a New Sensor of Seasonal Changes of Surface Loads2004

    • Author(s)
      Heki, K.
    • Journal Title

      AGU Geophys.Monograph Ser.vol.150 "The State of the Planet"(edited by R.S.J.Sparks, C.J.Hawkesworth)

      Pages: 177-196

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Journal Article] Snow load and seasonal variation of earthquake occurrence in Japan2003

    • Author(s)
      Heki, K.
    • Journal Title

      Earth Planet.Sci.Lett. 207

      Pages: 159-164

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Journal Article] Secular, transient and seasonal crustal movements in Japan from a dense GPS array : implication for plate dynamics in convergent boundaries

    • Author(s)
      Heki, K.
    • Journal Title

      The Seismogenic Zone of Subduction Thrust Faults (edited by T.Dixon, C.Moore)(Columbia University Press) (in press)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Book] 朝日選書「地球が丸いって本当ですか?」2004

    • Author(s)
      大久保, 里村, 飛田, 日置
    • Total Pages
      277
    • Publisher
      朝日新聞社
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Book] Dense GPS Array as a New Sensor of Seasonal Changes of Surface2004

    • Author(s)
      Heki, K.
    • Publisher
      アメリカ地球物理連合モノグラフ,"The State of the Planet"
    • Related Report
      2004 Annual Research Report
  • [Publications] Heki, K.: "Snow load and seasonal variation of earthquake occurrence in Japan"Earth Planetary Science Letters (Elsevier出版). 207. 159-164 (2003)

    • Related Report
      2003 Annual Research Report
  • [Publications] Heki, K.: "Dence GPS Array as a New Sensor of Seasonal Changes of Surface Loads"アメリカ地球物理連合モノグラフ,"The State of the Planet"(未定). (2004)

    • Related Report
      2003 Annual Research Report

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Published: 2003-04-01   Modified: 2016-04-21  

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