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Geological information is essential for a country like Japan, located at a tectonically active area, to ensure a safe and secure society. The Geological Survey of Japan gathers, compiles, and provides geological information and promotes its wider use. We also develop technologies to overcome various difficulties related to global environment protection, exploration of minerals and energy resources, and natural disaster mitigation, and coordinate international cooperation as a national representative.
Researchers at AIST, in collaboration with the University of Tokyo and University of Tsukuba, have identified a case in which strong ductile deformation near the hypocenters of large continental crustal earthquakes led to the rupture of subsurface faults. Most of the hypocenters of large continental crustal earthquakes along active faults are located at depths of around 10 km. At these depths, the high temperatures cause the rocks to deform ductilely when forces are applied. In Mie Prefecture, the Median Tectonic Line, the largest onshore fault in Japan, contains fault structures near the hypocenter of large earthquakes in the past are exposed on the ground surface. The area fraction of microcavities and the amount of strain due to ductile deformation were determined for rocks collected there. The results show that the area fraction of microcavities increases with the strength of ductile deformation and that rupture along the subsurface fault occurs when the area fraction exceeds 7.5%. The results of the present study reveal a case in which the development of microcavities due to ductile deformation along faults led to failure phenomena at locations where most large continental crustal earthquakes occur. Similarly, in metals where the development of microcavities due to ductile deformation leads to failure, failure can be predicted if the development of microcavities can be detected. Therefore, the findings obtained in this study would promote the development of short-term prediction technology.
(Left) Image of a continental crustal fault. Analysis of rocks near the hypocenter of past large earthquakes. (Right) Conceptual diagram of the process of fault rupture caused by ductile deformation. The smallest cavity size is less than a few hundred nanometers. *Figure modified from Yeo et al.(2025)
Researchers of AIST, Ritsumeikan University and University of Aizu have successfully identified areas of concentrations of ilmenite on the Moon's surface by data mining analysis using hyperspectral data acquired by the lunar exploration satellite KAGUYA (SELENE), and succeeded in identifying the highest concentrated areas of ilmenite. Detailed analysis of the identified concentrated areas using a high-spatial resolution terrain camera and a multi-band imager that can observe in multiple wavelengths of electromagnetic waves revealed that ilmenite is widely distributed in lunar pyroclastic deposits. Water, oxygen, iron, and titanium extracted from ilmenite (FeTiO3) are essential resources for human base construction and manned activities on the Moon. The results of this research are expected to contribute to the design plan for a sustainable resource extraction base on the Moon and to stimulate a new space industry market through the development of technologies for oxygen supply and manufacturing of lightweight materials on the Moon. Details of the results were published in the Journal of Geophysical Research-Planets on March 10, 2025.
Distribution map of ilmenite-rich areas on the Moon (marked in yellow) The background is a lunar brightness map (produced using multi-band data from the lunar explorer KAGUYA (SELENE)). The dark region in the figure is a region called "mare" covered with basalt, corresponding to the so-called "Moon rabbit” in Japan. *Data published in the KAGUYA (SELENE) Data Archive (https://darts.isas.jaxa.jp/app/pdap/selene/index.html.ja) (ISAS/JAXA) are processed and used.
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