Tohoku University, Kyoto University, and the University of Tokyo have succeeded in observing slow slips that occur in the subduction zone off the eastern coast of North Island in New Zealand through international joint research.The research results were published in the American scientific journal "Science".

 Slow slip is a type of "slow earthquake" that releases strain at a fault slip speed slower than a normal earthquake.It was also observed just before the XNUMX off the Pacific coast of Tohoku Earthquake, and the slow slip area moved significantly during the mainshock, which contributed to the enormous tsunami damage.However, since most of the slow slip slip area is below the seafloor, there were many unclear points about the details.

 In the "Hikrangi subduction zone" off the eastern coast of North Island, New Zealand, the Pacific plate subducts under the Australian plate at a rate of 3 to 6 cm per year, and slow slips occur every 18 to 24 months near the plate boundary.Crustal movements due to slow slip have been observed on land in New Zealand so far, and it is known that the amount of crustal movements is about 1 to 3 cm and lasts for about a week.

 In this international joint research by Japan, the United States, and New Zealand, a seafloor pressure gauge was installed in this area in 2014 and successfully recovered in 2015.As a result of the analysis, it was found that the slow slip faults are distributed to the shallower part than the estimation on the ground.It suggests that strains that cause earthquakes may be accumulated even at the plate boundary, which was previously considered to be unable to accumulate strains.

 In the future, while continuing similar pressure observations, we plan to conduct seafloor GPS observations to investigate steady plate movements and verify the uniqueness of repeated slow slips.In this sea area, excavation by the deep-sea exploration vessel "Chikyu" is also being considered.The company aims to elucidate the entire mechanism by acquiring slow-slip tomographic materials and combining them with the findings obtained from observations on land and on the seafloor.

Tokyo University

Established in the 10th year of the Meiji era.A university with the longest history in Japan and at the forefront of Japanese knowledge

The University of Tokyo was established in 1877 (Meiji 10) by integrating the Tokyo Kaisei School and the Tokyo Medical School.Since its establishment, it has developed education and research in a unique way in the world as a leading university in Japan and an academic center for the fusion of East and West cultures.As a result, many human resources have been produced in a wide range of fields, and many research achievements […]

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Foster a free academic style based on the spirit of "self-respect for self-weight" and open up a world of creative learning.

With the motto of self-study, we will continue to maintain a free academic style that is not bound by common sense, and develop human resources who have both creativity and practical ability.We provide an inclusive learning space that allows for diverse and hierarchical choices so that students themselves can choose a solid future through valuable trial and error. […]

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Create excellent research results that will be the source of innovation, and develop talented human resources who will lead the next generation

Tohoku University has a rich culture and humanity based on the tradition of "research first principle" since its opening, the idea of ​​"opening the door" and the spirit of "respect for practical science", and is a phenomenon of human beings, society and nature. In response to this, human resources with the ability to carry out intellectual exploration with a "scientific mind", demonstrating their expertise in various fields from an international perspective and leading […]

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