About the specifics of gasglaciodynamics phenomena

Abstract

A large number of paroxysmal catastrophic glacial pulsations of a huge scale and directional explosion-like nature in their epicentral zones are already known. Such pulsations under any suppositions and assumptions do not fit into the framework of traditional concepts of dynamic glaciology (and, in general, classical geography) and can neither be explained nor predicted within the framework of these ideas, on their basis. These phenomena, taking into account their pronounced features (a huge intensity air-blast, extremely high speeds of subhorizontal movement of the glacial-stone material, lightning speed of manifestation, quite different, including an exceptionally high degree of crushing of material, the formation of giant piles of ice-rock material at a multi-kilometer distance from its primary location, etc.) are most accurately identified as sudden gas-dynamic surge of glaciers. According to the historical data of the Kolka glacier catastrophic collapses since 1752 five cases of multi-scale surges were recorded, the nature of which was considered to be glaciodynamic on the basis of the impact on the main glacier of ice masses breaking from above and a sharp change in its mass balance. Analysis of the preparation process, the behaviour of catastrophic surges and continuing post-catastrophic phenomena at the site of the former glacier (fumaroles, “sand cone”, gas release) suggests that glaciodynamics itself, due to changes in mass balance or mechanical effects of breaking ice masses under the conditions of the Kazbek volcanic center, does not define critical conditions for a catastrophic glacier surge. Such situations can occur under certain geodynamic conditions, including seismic, tectonic, geothermal (due to postvolcanic processes or magmatic intrusions) factors.