Results from the first VHF profiler research radar in Costa Rica, operating at a central radar frequency of 46.6 MHz, are presented. Emphasis has been on studies of scattering layers detected in the altitude r...
Four samples containing ultrafine- and fine-grained magnetite of magnetoferritins and magnetotactic bacteria cells were magnetically characterized at both room and low temperatures. Transmission electron micro...
Investigations of superchrons are the key to understanding long-term changes of the geodynamo and the mantle’s controlling role. Granitic rocks could be good recorders of deep-time geomagnetic field behavior, ...
Authors: Chie Kato, Masahiko Sato, Yuhji Yamamoto, Hideo Tsunakawa and Joseph L. Kirschvink
High-latitude, small-scale plasma density irregularities are observed by the Advanced Land Observation Satellite 2, Phase Array type L-band Synthetic Aperture Radar-2 and the European Incoherent Scatter radar ...
Authors: Hiroatsu Sato, Jun Su Kim, Norbert Jakowski and Ingemar Häggström
A pyroclastic density current (PDC) was observed with the phreatomagmatic eruption of the Kuchinoerabujima volcano, southern Japan, on May 29, 2015. The PDC flowed down in all direction from the source crater,...
A simple and rapid technique to effectively remove volcanic smoke (vapor-dominated white plume) from visible or thermal infrared images of active craters is proposed, in which multiple photographs taken in a f...
Authors: Takeshi Hashimoto, Akihiko Terada and Ryo Tanaka
The uppermost structures of incoming oceanic plates have been investigated by seismic exploration surveys, primarily based on two-dimensional profiles. However, their regional-scale lateral variations and shea...
Authors: Takashi Tonegawa, Koichiro Obana, Gou Fujie and Shuichi Kodaira
This paper examines phreatic eruptions which are driven by inputs of magma and magmatic gas. We synthesize data from several significant phreatic systems, including two in Costa Rica (Turrialba and Poás) which...
A hot and acid crater lake is located in the Nakadake crater, Aso volcano, Japan. The volume of water in the lake decreases with increasing activity, drying out prior to the magmatic eruptions. Salt-rich mater...
The first year (December 2015 to November 2016) of IR2 after Akatsuki’s successful insertion to an elongated elliptical orbit around Venus is reported with performance evaluation and results of data acquisitio...
We report on the large-scale evolution of dipolarization in the near-Earth plasma sheet during an intense (AL ~ −1000 nT) substorm on August 10, 2016, when multiple spacecraft at radial distances between 4 and...
Authors: Rumi Nakamura, Tsugunobu Nagai, Joachim Birn, Victor A. Sergeev, Olivier Le Contel, Ali Varsani, Wolfgang Baumjohann, Takuma Nakamura, Sergey Apatenkov, Anton Artemyev, Robert E. Ergun, Stephen A. Fuselier, Daniel J. Gershman, Barbara J. Giles, Yuri V. Khotyaintsev, Per-Arne Lindqvist…
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...
A laser strainmeter with a 1500-m baseline was constructed at an underground site in Kamioka, Gifu Prefecture, Japan, and has been operating since August 2016. The laser interferometer measures the change in d...
Rotations of the principal stress axes due to great subduction zone earthquakes have been used to infer low differential stress and near-complete stress drop. The spatial distribution of coseismic and postseis...
A simple and efficient finite-difference scheme is developed to calculate seismic wave propagation in a partial spherical shell model of a three-dimensionally (3-D) heterogeneous global Earth structure for mod...
Authors: Hiroshi Takenaka, Masanao Komatsu, Genti Toyokuni, Takeshi Nakamura and Taro Okamoto
This study develops a three-dimensional viscoelastic model using the finite element method to understand the postseismic deformation that followed the 2011 Tohoku-Oki earthquake. The question of understanding ...
