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  • April 28, 2021

[Frontier Letter] Nonlinear wave growth theory of whistler-mode chorus and hiss emissions in the magnetosphere

Whistler-mode chorus and hiss waves controls dynamics of energetic electrons in the Earth’s magnetosphere. Omura (2021) describes nonlinear processes associated with the generation of chorus and hiss waves based on the theoretical developments in the past 15 years. The inhomogeneity factor due to the frequency variation and the gradient of the magnetic field plays a critical role in the generation process of rising-tone and falling-tone wave packets and associated electron… Read more

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  • April 22, 2021

[Frontier Letter] MOWLAS: NIED observation network for earthquake, tsunami and volcano

National Research Institute for Earth Science and Disaster Resilience (NIED) integrated the land observation networks established since the 1995 Kobe earthquake with the seafloor observation networks established since the 2011 Tohoku earthquake and tsunami as MOWLAS (Monitoring of Waves on Land and Seafloor) in November 2017. The purpose of MOWLAS is to provide comprehensive, accurate, and rapid observation and monitoring of earthquake, tsunami, and volcano events throughout Japan and its… Read more

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  • April 22, 2021

[Frontier Letter] Detection of triggered shallow slips caused by large earthquakes using L-band SAR interferometry

Fujiwara et al. (2020) studied the distribution of crustal deformation caused by large earthquakes in detail using space-borne SAR interferometry and identified many displacement lineaments. Large earthquakes tend to trigger shallow slips on other surrounding pre-existing faults. Subsequently, these triggered shallow slips release accumulated strain, which in turn results in displacement lineaments. The occurrence of such passive faulting creates weak, mobile fault planes that repeatedly move at the same location.… Read more

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  • April 22, 2021

[Frontier Letter] Volcanological challenges to understanding explosive large-scale eruptions

Large-scale explosive eruptions with caldera collapse are one of the causes of the global-scale disasters that modern society has never experienced. To understand the process of caldera-forming explosive eruptions and prepare for the potential risks, we need to understand the accumulation process of voluminous magma in the Earth's crust and the triggering mechanism of sudden destabilization and eruption of magmas from the magma chamber. This requires interdisciplinary researches that integrates… Read more

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