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  • July 6, 2018

Lateral variation of the uppermost oceanic plate in the outer-rise region of the Northwest Pacific Ocean

It has been known that Po waveforms are complicated due to high-frequency scattering within the mantle, but Tonegawa et al. (2018) attempted to retrieve Po-to-s (Pos) waves converted at crust-related interfaces by cross-correlating Po wave coda from the radial and vertical components. As a result, their results successfully showed the retrieval of Pos waves from the basement and oceanic Moho, and also demonstrated the effectiveness of this new approach by revealing lateral variations of Pos-wave emergence and layer-dependent shear wave anisotropy from the outer-rise to seaward regions. Click to view the article Read more

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  • September 25, 2018

Pyroclastic density currents associated with the 2015 phreatomagmatic eruption of the Kuchinoerabujima volcano

Though "low-temperature pyroclastic flow" is frequently observed with phreatic eruptions, there are few descriptions of its internal environment. The low-temperature pyroclastic flow of the 2015 eruption of Kuchinoerabujima volcano, southwestern Japan, provides geophysical data, video image, and geological descriptions of the deposits. The video image indicates that the velocity of flow exceeded 42 m/s. The dieback of the vegetation and deformation of some plastic materials in the flow, with absence… Read more

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  • October 1, 2018

Volcanic smoke reduction in visible and thermal infrared imagery

Photographs are not what you see. When I (TH) was a student back in 1990s, I was always frustrated with the volcano pictures that I photographed because they somehow did not look like what I thought I really saw. It was often due to white smoke in front. So I used to prefer hand-sketching in which I can build a complete compilation of my observation for several minutes as a… Read more

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  • November 29, 2018

Paleomagnetic studies on single crystals separated from the middle Cretaceous Iritono granite

Granitic rocks could be good recorders of deep-time geomagnetic field behavior, but paleomagnetic measurements on whole-rock granitic samples are often disturbed by the presence of unstable multi-domain magnetite. Kato et al. (2018) demonstrated that single plagioclase crystals separated from granitic rocks can be reliable recorders of the geomagnetic paleointensity by a series of rock-magnetic measurements and Tsunakawa-Shaw paleointensity experiments on plagioclase crystals of the middle Cretaceous Iritono granite, for which… Read more

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  • February 27, 2019

Imaging high-latitude plasma density irregularities resulting from particle precipitation: spaceborne L-band SAR and EISCAT observations

Particle precipitation represents an important source of irregular plasma density structures in the high-latitude ionosphere. Sato et al. (2018) used Synthetic Aperture Radar to image the small-scale plasma density irregularities under high levels of ionization of up to approximately 300 km over Tromsø, Norway. The irregular electron density is characterized by tens of kilometers of band-like structures aligned in the east-west direction with small patch-like structures. This study presents the… Read more