Item: Relationship between avalanche size and frequency based on avalanche video image observation in a warm snowy region
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Title: Relationship between avalanche size and frequency based on avalanche video image observation in a warm snowy region
Proceedings: International Snow Science Workshop Proceedings 2018, Innsbruck, Austria
Authors:
- Kazuya Akiyama [ Snow Avalanche and Landslide Research Center, Public Works Research Institute, Myoko, Japan ]
- Yusuke Harada [ Snow Avalanche and Landslide Research Center, Public Works Research Institute, Myoko, Japan ]
Date: 2018-10-07
Abstract: Avalanche observation site was established on the east side slope and foot of Mt. Gongendake (1104m a.s.l.), central Japan, in a warm snowy region where air temperature often exceeds 0°C in winter to observe meteorological elements and avalanche events using a seismometer and video cameras. Over four winter seasons from 2001/02 to 2004/05, 1504 avalanche tremors and 727 avalanche video images were recorded. Video images included 640 (88%) wet avalanches, and 431 (59%) avalanches were released on a particular slope where a disastrous avalanche which broke 11 houses and caused 13 deaths occurred on January 26, 1986. The concept of avalanche size was introduced to develop a scale of avalanches to investigate relationship between avalanche size (magnitude) and frequency using 431 avalanche video images of the most avalanche-prone slope. Research using original five avalanche sizes has shown that avalanche size (S) and frequency (n) are described on the basis of power-law relationship as Log n = -αS+β excluding minimum- size avalanches, and α and β coefficients were 0.65 and 3.7, respectively. Additionally, the coefficient α differed from one winter season to another and had a correlation with snowfall thickness or maximum snow depth in regression analysis. This observation site had been measured again in winter season of 2013/14 and obtained 442 avalanche tremors and 209 avalanche video images. Video images included 166 (79%) wet avalanches, and 131 (63%) avalanches were released on slope S1. Moreover, relationship between avalanche size and frequency or relationship between the coefficient α and snow variables in winter season of 2013/14 show a similar tendency in the past four winter seasons.
Object ID: ISSW2018_P01.4.pdf
Language of Article: English
Presenter(s):
Keywords: avalanche tremor and video image observation, avalanche size, avalanche frequency.
Page Number(s): 35-39
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