The 2015 Gorkha earthquake in Nepal triggered a large avalanche in Langtang, covering the village with avalanche debris and causing severe damage. The analysis of this disaster was conducted using an avalanche dynamics simulation, which estimated the potential hazards to the village. Avalanche dynamics simulations were performed using the TITAN2D model to obtain the appropriate input parameters for largescale avalanche flows. Using these input parameters, we calculated the avalanche flows for various initial volumes to obtain a lower bound for the potential hazard to Langtang Village. Based on the lower bound, it was estimated that both earthquake-induced and ice avalanches could threaten villages in the future. We also attempted to create a hazard map to estimate the areas around Langtang village where avalanches may have occurred. Using the Polynomial Chaos Quadrature, we were able to account for the uncertainties in the input parameters at a low computational cost.

In the Niseko area in Hokkaido, Japan, a unique set of rules -the “Niseko Rules”- control the opening and closing of gates to allow off-course skiing according to the avalanche danger level. In recent years, the need for scientific evidence that can correctly explain the Niseko Rules and the establishment of human resource training and organizational systems to ensure their continued operation has become apparent. Therefore, in collaboration with the local government and ski resorts, this study developed a system to generate snow redistribution information, which is important for determining avalanche risks in the Niseko area. The constructed system provides wind observation data at multiple points in ski resorts, wind spatial distribution simulations based on observational data, snow redistribution simulations based on wind spatial distribution simulations, and wind spatial distribution and snow redistribution forecast information based on meteorological forecasted data. Research has continued to improve the accuracy of these simulations. Agile research and development are also underway to improve the usability of the system in ski resorts and affected municipalities.

To understand the physics, chemistry, and ecosystems of sea ice and develop technologies for sea ice observation, multidisciplinary research for sea ice and under-ice water was conducted at the Saroma-ko Lagoon, Hokkaido, Japan from end of February to beginning of March 2023. Under-ice water properties were monitored to quantify heat budgets and interactions with sea ice biogeochemical properties. Sea ice cores were collected to understand the interaction with the under-ice water affected by river water discharge. Physical and biogeochemical parameters such as temperature, salinity, oxygen isotopic ratio, sea ice structure, environmental DNA, and concentrations of gases, nutrients, chlorophyll a, and trace metals were measured. Incubation experiments with ice algae were conducted. Equipment such as a melt probe for high vertical resolution sea ice sampling and a sea ice drilling robot to install under-ice communication devices were tested to develop the technologies for future Arctic and Antarctic expeditions. Multidisciplinary research of sea ice and under-ice water provided interactions between sea ice communities, including younger generations, that will be useful for future studies of sea ice in polar oceans.

The Hijiori avalanche test site, Ohkura Village, Yamagata Prefecture, Japan, was established during the winter of 2010/11 to observe small-scale avalanches in warmer regions. The site has been monitored by meteorological observation, and slope has been monitored using a web camera and UAV aerial photography since the winter of 2018/19. The regionʼs warm climate makes it prone to glide avalanches, and webcam monitoring has confirmed 56 avalanches in 13 winters, of which 97 % are glide avalanches. In winter, the wind direction is predominantly west-northwest or northwest. It is almost directly orthogonal to the ridge of the target slope, which makes it easy for cornices to develop. Simulations were also conducted using photographic and UAV data, which are being verified. To use the Hijiori avalanche test site more effectively in the future, we will continue to publish information that contributes to avalanche research by organizing the accumulated data.

Rising temperatures and melting of snow and ice since 2000 CE may result in coastal soil regions in Greenland providing more mineral particles to the Greenland ice sheet than before. To examine seasonal variations of the concentrations and source regions of mineral particles in recent snow in inland Northeast Greenland, we analyzed the total (i.e., soluble and insoluble) concentrations of major metallic elements (Al, Ca, and Fe) and the size distributions of mineral particles in snow pit samples covering 2013-2017 at the East Greenland Ice Core Project site. The total concentrations of metallic elements showed clear seasonality with spring maxima, indicating that the mineral particle concentrations peaked in this season. Volcanic products from the 2014-2015 eruptions of Bárðarbunga, Iceland, had little effect on the metallic element concentrations. The increased Ca/Al ratio, Ca solubility, and fine particle fraction (≤5 μm) in winter–spring indicated that the relative contributions of mineral particles originating from distant arid regions increased in those seasons. In summer–autumn, the Ca/Al ratio and Ca solubility decreased, and the coarse particle fraction (>5 μm) increased, suggesting that the relative contributions from coastal soil regions in Greenland increased in those seasons.