Deposits of volcanic. Wet flows Identifying deposits of lahars, debris avalanches, and water floods in volcanic terrain / Вулканические отложения. Определение лахаров, сход обломочных лавин и наводнений в вулканической местности

Gravity-driven fows of material emanating from volcanoes during or following eruptions can range from fowing molten rock to fowing denser-than-air volcanic gas. But the bulk of volcanic fows involve twophase mixtures of solid rock fragments and a fuid—either liquid water or gas composed of air±volcanic gases. Deposits of the various particle–fuid fows derive their physical characteristics from mixture properties and from the particle–fuid interactions involved in both the transport and deposition of the mixtures. Interactions can differ substantially among emplacement processes. Flow types vary with the ratio of solid particles to fuid and with fuid composition. Volcanic “wet” fows involve variable mixtures of liquid water+volcanic rock particles (±ice fragments)—lahars, debris avalanches, and water foods. Their deposits exhibit properties differing only slightly from deposits emplaced by “dry” fows involving gas+volcanic rock particles and from deposits emplaced by fowing glacier ice. Until now, wetfow deposits have not been systematically described in detail. Recognition of the characteristic features of any volcanic or volcaniclastic deposit can lead to identifcation of its emplacement process, which is critical for accurate volcanic hazard assessment. <...>