Tephra occurrence in Alaska: a map-based compilation of stratigraphic tephra data

The principal hazard associated with future explosive eruptions of Alaska volcanoes is the generation of volcanic ash clouds which are explosively blasted high into the atmosphere and then drift away from the volcano with the wind. The fragments in the ash cloud (tephra) vary in size and the heavier particles fall near the source while finer particles travel downwind. This transported tephra will fall out of the cloud and accumulate on surfaces and structures, contaminate water sources, and infiltrate electronics and motors. The weight of significant accumulations may collapse structures and cause other damage. Chronic exposure to ash may be a significant public health hazard. This publication presents the frequency and location of tephra fall throughout Alaska and into the Yukon Territory of Canada, resulting from eruptions of Alaska volcanoes from the Pleistocene to the present. The tephra occurrence map facilitates better visualization of areas in Alaska with past occurrences of ashfall. The map is a useful indicator of regional potential ashfall hazards. All files can be downloaded free of charge from the DGGS website (http://doi.org/10.14509/30059).