Explosive Activity of Avachinsky Volcano (Kamchatka): Tephra Dispersal, Eruption Magnitudes and Related Hazards

Understanding the frequency, dispersal areas, and volumes of tephra fall deposits is essential for assessing related hazards and estimating magma output rates. At the same time, deriving quantitative eruption parameters is often hindered by limited field data on eruptive deposits and, in island-arc settings, by the dispersal of airborne tephra over the sea, where mapping depends on the availability of sediment cores. For frequently erupting volcanoes, obtaining volume estimates are especially challenging because of difficulties in field mapping of numerous and often similar looking tephra fall deposits. In this paper, we present newly calculated conservative estimates of dispersal areas, tephra volumes, and eruption magnitudes for Avachinsky volcano (Kamchatka, NW Pacific), one of the most active and hazardous Holocene volcanoes, located close to the Petropavlovsk-Kamchatsky–Elizovo urban area. Our estimates are based on a compilation of published isopach maps and tephra occurrence sites, complemented by new data, and on a systematic approach to tephra volumes calculations. This research provides a solid basis for future efforts to define the Avachinsky magma production rate and to improve hazard modeling.