A preliminary volcanic ash fall susceptibility map of Canada

This paper presents a theoretical method for estimating volcanic ash fall rate from the eruption of Sinabung Volcano on February 19, 2018 using an X-band multi-parameter radar (X-MP radar). The X-MP radar was run in a sectoral range height indicator (SRHI) scan mode for 6° angular range (azimuth of 221°–226°) and at an elevation angle of 7° to 40° angular range. The distance of the radar is approximately 8 km in the Southeastern direction of the vent of Mount Sinabung. Based on a three-dimensional (3-D) image of the radar reflectivity factor, the ash column height was established to be more than 7.7 km, and in-depth information on detectable tephra could be obtained. This paper aims to present the microphysical parameters of volcanic ash measured by X-MP radar, which are the tephra concentration and the fall-out rate. These parameters were calculated in a two-step stepwise approach microphysical model using the scaled gamma distribution. The first step was ash classification based on a set of training data on synthetic ash and its estimated reflectivity factor. Using a naïve Bayesian classification, the measured reflectivity factors from the eruption were classified into the classification model. The second step was estimating the volcanic ash concentration and the fall-out rate by power-law function. The model estimated a maximum of approximately 12.9 g·m-3of ash concentration from the coarse ash class (mean diameterDn= 0.1 mm) and a minimum of approximately 0.8 megatons of volcanic ash mass accumulation from the eruption.

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Growth and decay of palsas and peat plateaus in the Macmillan Pass–Tsichu River area, Northwest Territories, Canada

Canadian Journal of Earth Sciences ◽

10.1139/e79-122 ◽

1979 ◽

Vol 16 (7) ◽

pp. 1362-1374 ◽

Cited By ~ 35

Author(s):

G. P. Kershaw ◽

Don Gill

Keyword(s):

Northwest Territories ◽

Volcanic Ash ◽

Late Winter ◽

White River ◽

The Past ◽

Ash Fall ◽

Tall Plant ◽

Reduction Of Area ◽

Crustose Lichens ◽

Peat Plateaus

Macmillan Pass, at 1350 m asl (above sea level), is located in the Selwyn Mountains at the Yukon–Northwest Territories border (63 °15′N, 130°02′W). This area lies within the discontinuous but widespread permafrost zone. Palsa–peat plateau complexes cover 0.7% of the 235 km2 study area and are found in bog and fen depressions at elevations from 1285–1690 m. Palsa heights range from 0.15–9.75 m and diameters from 3.25–75.0 m; peat plateaus have maximum heights of 2.5 m and maximum diameters of 225 m. Both features are vegetated by Cladina-Betula glandulosa, Cladina-Polytrichum-Cetraria, and crustose lichens-Polytrichum plant communities.Palsas and peat plateaus are windswept during winter. On surfaces which support recumbent (5–15 cm tall) plant communities there was an average of only 7.5 cm of snow during late winter 1978. Snow cover was thinner by a ratio of 1:4 compared to control areas.These permafrost features have formed since the White River volcanic ash fall of 1220 BP. On palsas and peat plateaus this ash occurs at an average depth of 21 cm and has an average thickness of 11.6 cm.Shrinkage and (or) total decay of palsas and peat plateaus has occurred during the past 34 years. In one palsa field this represents a 34% reduction of area whereas in two others, 100%. The areal extent of some peat plateaus has also been reduced.

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More thoughts about Thera

Greece and Rome ◽

10.1017/s0017383500016685 ◽

1972 ◽

Vol 19 (1) ◽

pp. 37-46

Author(s):

J. V. Luce

Keyword(s):

Bronze Age ◽

Volcanic Ash ◽

South Coast ◽

Late Bronze Age ◽

Intrinsic Interest ◽

Ash Fall ◽

Magazine Articles ◽

The Village ◽

Firm Evidence ◽

Initial Exploration

In 1965 the notable paper ‘Santorini Tephra’ by D. Ninkovich and B. C. Heezen provided the first firm evidence that the Late Bronze Age eruption of the Thera volcano directly affected the eastern part of Crete through ash fall-out. In July 1967 Professor Marinatos's initial exploration of a settlement buried under volcanic ash near the village of Akrotiri on the south coast of Thera received worldwide publicity, partly for its intrinsic interest, but perhaps even more because the discovery was linked with the magic word Atlantis. The whole subject was then extensively aired in newspaper and magazine articles, and three books on the theme of Thera-cum-Atlantis appeared in 1969.

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