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Graduate School of Science and Engineering
Science of Environment and Mathematical Modeling

Earth System Science / Environmental Magnetism Laboratory

Seeking to understand the earth system and environmental changes

Staff

Akira HAYASHIDA
[Professor]
MD
Telephone : +81-774-65-6680
hayashida
Office : HS-110
Database of Researchers
Koji FUKUMA
[Associate Professor]

Office : KE-309
Database of Researchers

Research Topics

Elucidating the earth's magnetic field variation and obtaining magnetic records of climate changes

Research Contents

One of the characteristics of global environmental issues is that materials and energies generated by human activity can cause disturbances to natural systems, which might constitute threats to human existence. Carbon dioxide and CFCs, for example, while not toxic themselves, give rise to major changes in the earth systems, which in turn make people anxious and bring troublesome problems to our life. Studying nature and change of the earth system is indispensable to understanding the global environment issues.
On the basis of earth science, the Earth System Science/Environmental Magnetism Laboratory conducts research of analyzing, evaluating and modeling climate and geospheric environment changes. Rocks and sediments of seas and lakes contain magnetic minerals such as iron oxides or iron sulfides that bear ferri- or antiferromagnetism. Just as magnetic tapes and floppy disks store every sort of information, magnetic minerals in rocks and sediments can record the ancient earth's magnetic fields as natural remanent magnetization. Paleomagnetism is a branch of the earth science: to decode the record of the earth's magnetic fields, to date rocks or sediments based on the magnetic polarities, and to understand continental drift or tectonic movements. On the other hand, composition, concentration and grain size of the magnetic minerals can tell us the provenance and transport of sediments, which leads to clarifying the natural environments at the time of deposition, and hence hydrologic or climate changes; this discipline is called environmental magnetism. Global environment and tectonics research based on magnetic measurements is presently used for a wide variety of samples and is expected to contribute greatly to our understanding of the global environment and its near-future state. The sedimentary record is not only an archive of planetary and human history, but also a target of our intellectual challenges exploring the unknown world.
<1> Environmental change analysis using the magnetic properties of sediments
We obtain the magnetic properties of sediment samples from seas and lakes and interpret the data on how the magnetic properties are related to environmental and climate change. We conduct time series analysis and factor analysis on magnetic properties data, perform geographic information system analysis, and try to model the material transport and detect quantitative environmental indicators.
<2> Paleosecular variation, paleointensity change, and the history of geomagnetic polarity reversal
Geomagnetic polarity reversal is a simultaneous phenomenon occurring on a planetary scale, which constitutes a global isochronous horizon. In addition, geomagnetic secular variation and changes in geomagnetic field intensity are effective for dating and correlation of strata in higher resoluton and are used widely in studying climate change and human evolution. They also provide important clues to understand the dynamics operated in the deeper part of the earth.
<3> Formation and development of the Japanese Islands based on remanent magnetization measurements
Paleomagnetic directions are essential clues for reconstructing ancient positions of lithospheric plates, land blocks and small rocky formations, and also provide valuable information on the development of the Japanese Islands. Focusing on widespread tephra that deposited simultaneously in a short period, one can compare remanent magnetization acquired at the same time over a vast area, which allows us to detect crustal movements that took place in the Quaternary Period.

Keywords

  • Earth systems
  • Environmental magnetism
  • Rock magnetism

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