Earth’s Cryosphere, 2017, Vol. XXI, No. 6, p. 103-111

FORMATION OF WATER FLOW IN LAHARS FROM ACTIVE GLACIER-CLAD VOLCANOES

I.B. Seynova¹, S.S. Chernomorets¹, M.D. Dokukin², D.A. Petrakov¹,
E.A. Savernyuk¹, A.A. Lukashov¹, E.A. Belousova¹

¹ Lomonosov Moscow State University, Faculty of Geography,
1, Leninskie Gory, Moscow, 119991, Russia; devdorak@gmail.com

² High-Mountain Geophysical Institute,
2, Lenina prosp., Nalchik, 360030, Kabardino-Balkaria Republic, Russia; inrush@bk.ru

Glaciers and snow cover on volcanoes are among main sources of meltwater in lahars. Review of open databases on volcanoes, modern glaciers and snow cover allowed us to identify 144 glacier-clad volcanoes as well as 226 volcanoes with and 298 volcanoes without seasonal snow cover. We have compiled a sketch map which illustrates the global distribution of volcanoes covered with ice and snow and analyzed available reports on lahars from such volcanoes. Evidence on eruptions of Redoubt (Alaska, 1989–1990) and Nevado del Ruiz (Colombia, 1985) volcanoes made basis for a plausible model explaining the transformation of volcanic (eruption) to hydrological (lahar) processes. Interaction of pyroclastic flow with snow and ice which causes their melting occurs by the mechanisms of convective mixing and rapid turbulent heat exchange, respectively. The melting rate at turbulent heat transfer is at least ten times faster than that of static melting under eruption products.

Lahar, slush flow, nival-glacial zone, paroxysmal eruption, tephra, pyroclastic flow, lava flow, thermodynamic processes, phreatic blast, volcano