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Guo Biao of Institute of Geology went to Japan to attend Japan Geoscience Union (JpGU)-American Geophysical Union (AGU) Joint Meeting (2017)

2017/10/18 15:04:14

1. General information of the meeting


JpGU-AGU Joint Meeting (2017) is the first large international academic conference that is jointly held by Japan Geoscience Union (JpGU)-American Geophysical Union (AGU). This meeting, covering fields of Space and Planetary Sciences, Atmospheric and Hydrospheric Sciences, Human Geosciences, Solid Earth Sciences, Biogeosciences, General (Education and Outreach), and Multidisciplinary and Interdisciplinary, is one of the large-scale conferences on geosciences with the most attendance in the history in Japan. Besides native scientific researchers, more than half of the attendee is from the other countries around the world, including a lot of researchers from universities and institutes of China like University of Science and Technology of China, Peking University, University of Chinese Academy of Sciences, as well as institutes of China Earthquake Administration and Chinese Academy of Sciences.

2. Characteristics of sessions participated


Sessions that Guo Biao participated are as follows:


Session "New perspectives on East Asia geodynamics from the crust to the mantle" (S-IT29 in Science of the Earth's Interior & Tectonophysics, Solid Earth Sciences)  focused on the structure of continental crust-upper mantle and characteristic of tectonic deformation in East Asia under the joint influence from the subduction of the Pacific plate and the northward compaction of the India subcontinent. This session contained a lot of research reports in different disciplines like chronology, geology, and geophysics, including many interdisciplinary results.


Session "Structure and dynamics of earth and planetary mantles" (S-IT23 in Science of the Earth's Interior & Tectonophysics, Solid Earth Sciences) concerned primarily about deep structure and evolution of the earth, interaction of different slabs. Generally, this session focused on earth dynamics on global or regional scales.


Session "Earthquake prediction and forecast" (S-IT14 in Science of the Earth's Interior & Tectonophysics, Solid Earth Sciences) assesses scientifically natural disasters like earthquakes and volcanoes on the basis of various kind of data observed. And several theoretical researches, data observation methods, and practical applications were presented in this session,.


Session "JpGU-AGU great debate: Geoscience and Society" in Union Session invited experts in relevant fields to discuss major issues which are debatable at present and to address these issues and their development in the future, including the role of geoscientists in the society, careers of young scientists in the future, prediction and forecast of earthquakes and volcanoes, relationships and interactions among academic organizations, public and governments.


3. Highlights of the meeting


At this JpGU-AGU joint meeting, Guo Biao primarily concerned the development of seismology, structure and dynamics of crust-upper mantle in East Asia, frontiers in geoscience, of which a lot could be highlighted.


(1) Multidisciplinary comprehensive research and studies using multiple methods have become the main currency in geoscience. And amounts of research with  integration of geology and geophysics were reported in the meeting, such as the evolution of the Pacific subduction zone, subduction process, and age distributions of subduction slabs combined with chronology and thermodynamics, and joint inversions or comprehensive research utilizing different geophysical fields like seismic noise, body waves, surface waves, and gravity.


(2) Scientists in Japan have accumulated a great amount of data in the field of earthquake prediction. In the meeting, they presented a lot of earthquake observations and macro-anomaly data for many years. Besides, they analyzed precursor information of earthquakes and volcanoes jointly by various data like GPS, remote sensing, infrasound, noise, and meteorology.


(3) With the development of technology, new observation methods have been applied in seismic observation, like new sea seismograph.


(4) Open access e-journal could be the future of scientific publishing. There are more open access e-journals than traditional scientific journals advertising in this meeting. And, in the future, open access e-journal will become the main currency of scientific publishing according to the discussion and analysis in the session "Future of scientific publishing in geoscience (U01)", because there are many advantages of open access e-journals like quickly publishing, interactive discussion with readers, and real-time modification.


(5) This meeting adopted a new way of discussion that several scientists were invited, standing on the stage, to argue with some debated issues or issues that the public concerns a lot as well as some perspective issues in geoscience, such as anticipations and possible achievements of earthquake prediction in the next 50 years, exchanges between academic conferences and the public, and communications between academic groups and governments.


4. What was presented by Guo Biao


Guo Biao spent most of his time in the session "New perspectives on East Asia geodynamics from the crust to the mantle" (S-IT29 in Science of the Earth's Interior & Tectonophysics, Solid Earth Sciences) and gave a presentation "Lithosphere rebuilding of the Alashan and Ordos by upper mantle upwelling: evidence from multiscale teleseismic tomography" in the form of poster.


In the presentation, Guo Biao reported the P wave velocity structure of the upper mantle (< 800 km deep) of the western margin of Ordos and adjacent regions derived from seismic tomography. This work was based on approximately 16000 teleseismic P wave travel time data of 9641 earthquakes recorded by 23 permanent and 678 temporary stations in the scientific array of the programme "Himalaya II", employing the sparse constrained multiscale tomographic method. The results reveal a lithospheric tectonic boundary between the Alashan block and the Ordos basin near 104°E, illustrating that the two blocks respectively belong to different tectonic units. Moreover, bounded by the latitude 38°N, there is remarkable difference in velocity of the lithosphere in the western margin of the Ordos block. The upper mantle at depth of 200-300 km in the southern Ordos has a high velocity anomaly, while the upper mantle in the northern Ordos shows a low velocity anomaly. It was further inferred that mantle upwelling, caused by the upper mantle perturbation triggered by the northeastward extrusion of the Tibetan Plateau and the Alashan block as well as the detachment of the lithosphere, resulted in the lithosphere rebuilding and thinning of the northwestern margin of the Ordos. Furthermore, such upwelling could be one of deep dynamic factors for the formation of the tectonic boundary at 104°E and 38°N.

Sketch map of the dynamics in the upper mantle

5. Recognitions and experiences

The strongest feeling about the JpGU-AGU joint meeting is that the Annual Meeting of Chinese Geoscience Union (CGU meeting) is not as internationalized as this meeting. Every year, CGU meeting invites some well known international experts to  give presentations which are generally summarized or retrospective reports rather than the latest frontier results. Sometimes, many excellent scientific results are not obtained by well known experts but young doctors who have been working on the really frontier issues.


On the other hand, there are a lot of great advantages in the field of geoscience in China. Firstly, there are comprehensive research fields in China covering almost all the directions in geoscience. Secondly, we have a great amount of young scientific researchers. And finally, China hosts numerous characteristic geological phenomena and complex and unsolved problems which attract attention of scientists all over the world, such as those in the Tibetan Plateau, Tian Shan, Dabieshan, and so on.


Through attending the JpGU-AGU joint meeting, some thoughts about geoscience and academic conferences come out that we should hold international academic conferences together with foreign academic organizations, especially those in  major countries and regions of scientific researches, strengthen presentations of multidisciplinary research results, attract young scientific researchers, set up more prospective issues, increase academic communications between humanities or social sciences and natural sciences, and enhance popularization of science to teenagers.