Ryo Nakanishi

北海道太平洋沿岸西部は，17世紀の地震・津波の規模や波源を明らかにする上で重要な地域である．そこで歴史記録に残っている1640年の駒ヶ岳噴火にともなう山体崩壊津波の規模を推定するために，内浦湾から胆振海岸西部にかけて17世紀のイベント堆積物の分布を明らかにした．イベント堆積物の粒度・鉱物組成は海浜周辺の砂とよく類似しており，内陸に向け薄層化・細粒化・軽量化を示す．本砂層は，内浦湾から登別にかけて1640年の駒ヶ岳噴火テフラ（Ko-d）によって覆われていることから，1640年の駒ヶ岳山体崩壊にともなう津波堆積物であると判断される．現世の津波堆積物調査結果を基に各調査地点の津波堆積物分布における浸水深1mが妥当かを評価し，数値シミュレーションを用いて1.20km3を超える山体崩壊物流入量を再現し遡上高を求めたところ，内浦湾沿岸から白老周辺までは，両者の推定遡上高が調和的な結果となった．この津波規模は約Mt 7.9-8.2と見積もられる．

The tephra layers known with eruption ages play an important role in an investigation of tsunami history and archaeology in addition to volcanic history in Hokkaido, Japan. We investigated the event and tephra layers of the Late Holocene in the Pacific coast of western Hokkaido, where the stratigraphy of the Late Holocene has not been clarified. Surveys in coastal peatlands, mostly undisturbed deposits, have allowed for the discovery of thin tephra layers. The newly discovered tephra layers at t

Abstract Sediment transport modeling (STM) is a potentially effective tool for estimating the magnitude of tsunamis and earthquakes without historical records. However, the application of STM to prehistorical tsunamis is challenging because of multiple uncertainties in topography and roughness. Along the coast of Hidaka, Hokkaido, Japan, there is potential to conduct STM even in the absence of historical records because comprehensive geological data for the coastal evolution during the Holocene

By using a transparent digitizer and a personal computer, we tried a quantitative analysis of ataxia in the upper limbs. A total of 25 upper extremities of 13 patients with spino-cerebellar degeneration (SCD) and 140 upper extremities of 70 normal volunteers were tested by two types of tasks. One was the free speed trace of a circle presented on the display (free circle), and the other was the pursuit of a target moving on a circle at a fixed speed (pursuit circle). The digitizer was put on a co

Abstract With their complex cycles and rupture modes, infrequent megathrust earthquakes require a high‐resolution spatiotemporal record of tsunami inundations over thousands of years to provide more accurate long‐term forecasts. The geological record suggests that Mw > 8 earthquakes in the Kuril Trench occurred at intervals of several hundred years. However, uncertainties remain regarding the rupture zone, owing to the limited survey areas and chronological data. Therefore, we investigated th

Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Journal of Geophysical Research - Solid Earth. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing an older version [v1]Go to new versionSpatial extension of the mid to late Holocene sedimentary record of tsunamis along the Southern Kuril Trench, Hokkaido JapanAuthorsRyoNakanishiiDJuichir

Geological evidence, such as tsunami deposits, is crucial for studying the largest rupture zone of the Kuril Trench in Hokkaido, Japan, due to its poor historical record. Although 17th-century tsunami deposits are widely distributed across Hokkaido, the presence of multiple wave sources during that period, including the collapse of Mt. Komagatake, complicates the correlation with their wave sources. Understanding the regional distribution of these tsunami deposits can provide valuable data to es

Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at G-Cubed. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v2]Spatial extent of the mid- to late Holocene sedimentary record of tsunamis along the Southern Kuril Trench, Hokkaido, JapanAuthorsRyoNakanishiiDJuichiroAshiYosukeMiyairiYusukeYokoyamaiDSee all a

Abstract Ground motion prediction equations (GMPEs) in offshore regions are important not only for earthquake early warning systems and strong motion prediction but also for evaluating the durability of subsea structures and tsunami risks associated with seafloor slope failures. Since soil conditions and propagation paths differ between onshore and offshore areas, it is desirable to develop a GMPE specific to the seafloor. Previous GMPE models have some problems, such as being influenced by buri

Rising sea levels and associated coastal topography changes are expected to increase coastal vulnerability to tsunamis. Reliable records of the periodicity of the most damaging tsunamis, with recurrence intervals of several centuries, are often incomplete. To understand the likelihood of coastal disasters that would be worsened by sea-level rise, as well as their possible occurrence leading to the actual extent of inland inundation, it is useful to examine the geological record of the mid-Holoce

Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Journal of Geophysical Research - Earth Surface. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v1]Sediment Transport Modeling Based on Geological Data for Holocene Coastal Evolution: Wave Source Estimation of Sandy Layers on the Coast of Hidaka, Hokkai