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  • November 13, 2017

Performance of Akatsuki/IR2 in Venus orbit: the first year

It is essential for instruments, that work in space or at or near the target bodies, to be characterized under the actual operating conditions. Establishing the procedure of data processing is important as well. IR2, which cools its sensor and optics by a cryo-cooler, is affected in particular by thermal environment in the orbit. Satoh et al. (2017) made efforts to produce the data with best possible quality by understanding… Read more

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  • November 7, 2017

Near-Earth plasma sheet boundary dynamics during substorm dipolarization

Nakamura et al. (2017) report on the evolution of the near-Earth plasma sheet boundary during an intense substorm. Based on multi-point analysis using the four-spacecraft measurements from Magnetospheric Multiscale (MMS) together with Geotail and GOES spacecraft and comparison with MHD model of the reconnection jet, spatial structure of the high-speed plasma flows and associated field-aligned current pattern are deduced. It is shown that the dynamics in the boundary region of the near-Earth plasma sheet are controlled both by the Earthward flow braking process and by the accumulated magnetic flux due to near-Earth reconnection evolving tailward. Click to view the article Read more

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  • August 21, 2017

Volcanic activity on Io and its influence on the dynamics of the Jovian magnetosphere observed by EXCEED/Hisaki in 2015

Jupiter's moon Io, which orbits deep inside the magnetosphere, is the most geologically active object in the solar system. Kurdalagon Patera, a volcano on Io, erupted in 2015 and became a substantial source of Jovian magnetospheric plasma. Based on Earth-orbiting spacecraft observations, Io plasma torus (IPT) exhibited the peak intensity (nearly double) of ionic sulfur emissions roughly 2 month later, followed by a decay phase. This environmental change provides a… Read more

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  • July 11, 2017

Design and operation of a 1500-m laser strainmeter installed at an underground site in Kamioka, Japan

A laser strainmeter with a 1500 m baseline was constructed at an underground site in Kamioka, Gifu Prefecture, Japan. The interferometer using a high frequency-stabilized laser measures the change in distance between two retroreflectors in the tunnel of the KAGRA gravitational-wave telescope. Since operations began in August 2016, ground motions with various timescales have been detected. The tidal waveform agrees with the theoretical waveform after topographic corrections. The strain spectrum indicates the lowest background noise of less than 10−12 in the mHz band. The strainmeter provides a new method for observing low frequency ground motion on seismic, geodetic, and intermediate timescales. Click to view the article Read more

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  • June 26, 2017

The spatial distribution of earthquake stress rotations following large subduction zone earthquakes

Hardebeck (2017) explores the spatial distribution of stress rotations caused by great subduction zone earthquakes. These stress rotations imply that the earthquake stress drops are of similar magnitude to the background stress, consistent with low differential stress levels in subduction zones. The largest stress rotations are consistently found just above the Moho depth of the overriding plate, a depth range where large coherent slip patches are observed in great earthquakes, and where high fluid pressures have been imaged. Both of these processes could contribute to the low background stress levels. Click to view the article Read more

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  • May 10, 2017

EPS Young Researcher Award 2016

Michiyo Sawai, Takehiro Hirose, Jun Kameda (2014), Frictional properties of incoming pelagic sediments at the Japan Trench: implications for large slip at a shallow plate boundary during the 2011 Tohoku earthquake, Earth, Planets and Space, 66:65, doi: 10.1186/1880-5981-66-65 The slip at the shallow part of the megathrust triggered the destructive Tsunami associated with the Tohoku Earthquake in 2011. Thus, it is important to understand how such a large rupture can… Read more

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  • May 10, 2017

EPS Excellent Paper Award 2016

Yushiro Fujii, Kenji Satake, Shin’ichi Sakai, Masanao Shinohara, and Toshihiko Kanazawa (2011), Tsunami source of the 2011 off the Pacific coast of Tohoku Earthquake, Earth Planets Space, 63, 815–820, doi:10.5047/eps.2011.06.010 This paper compiled the Tsunami waveform data from tide gauges, GPS wave gauges, and ocean bottom pressure gauges associated with the 2011 Tohoku Earthquake. From the waveform inversion, the authors successfully explained the two-step waveforms, which were the most outstanding… Read more