AVALANCHES, DEBRIS-FLOWES AND LANDSLIDES ON THE MONERON ISLAND

• Main Author: Н.А. Казаков
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: Для почтовых отправлений: 199155 Санкт-Петербург, а/я 136, Редакция журнала «Гидросфера. Опасные процессы и явления» / For mail: 199155 St. Petersburg, PO Box 136 Editorial Board of the «Hydrosphere. Hazardous processes and phenomena». 2020
• Subjects: avalanche; avalanche catchments; avalanche geosystem; coherent debris-flow; debris-flow; debris-flow basin; debris flow process; debris-flow geosystem; landslide; Moneron Island; грязекаменный сель; лавина; лавинная геосистема; лавиносбор; остров Монерон; оползень; оползневой массив; селевой бассейн; селевая геосистема; селевой процесс; Sakhalin
• Online Access: https://hydro-sphere.ru/index.php/hydrosphere/article/view/56

On Moneron Island actively develops avalanche, debris-flow and landslide processes. Avalanches with a volume from 25 to 70 000 m3 are formed in avalanche catchments and avalanche slopes with a height of 70-300 m and a steepness of 35°-50°. Avalanches are formed that are associated with recrystallization of the snow column and the formation of weak layers inside it and at time during of snow fall and blizzard. Debris-flow are formed in the numerous streams, in the craters of denudation and landslide cirques and troughs. In small watercourses, connected debris-flows with a volume from 300 to 50 000 m3 and disconnected suspended streams with a volume of up to 1,000 m3 are formed. In large debris-flow are volume more them 50,000m3. The debris-flow period lasts from April to November. Repeatability of debris-flows of up to 3,000 m3 – 1 time in 5-7 years, debris-flows of more than 10,000 m3 – 1 time in 10-12 years. Surface landslides are formed (volume of 500-5 000 m3) with a depth of capture of rocks up to 2.5 m (mainly on the slopes facing the sea coast with a steepness of 40-50°) in low-power (1.0-2.5 m) deluvial loose deposits of fractured basalts and mudstones. Block landslides in rocks with a volume of 50000-500000m3 or more with a rock capture depth of more than 10 m are formed on the coastal slopes. Block landslides descend during earthquakes and (or) heavy prolonged rains into the sea area and can cause tsunamis that can reach the shores of Sakhalin Island, Hokkaido and the Maritime provinces. On the bodies of old landslides secondary block asequent landslides of slow displacement and landslides of viscoplastic displacement with a volume of 5000-30000m3 with a depth of rock capture up to 10 m develop. The formation of landslides and debris-flows of large volumes and mass formation of landslides and debris-flows occurs when heavy intense precipitation falls after the previous moistening of rocks caused by heavy prolonged rains. Daily precipitation can reach 89.0 mm. In 1914, 4 people was killed in an avalanche ...