Abstract
Several examples of tribological research in volcanic settings are presented in conjunction with an overview of volcanic
phenomena. Friction plays a fundamental role in both the formation and erosion of volcanoes. During eruptions where lava
ascends through conduits, however, abrasion predominates over friction. Many studies of pyroclastic flow descent incorporate the
concepts of shallow and two-layer flow friction, with friction coefficients typically determined through simulation. The air content
ratio during pyroclastic flow descent is cited as a key factor in controlling this friction coefficient. Many studies examine slope
sediment collapse related to volcanic erosion processes from a geotechnical perspective. These studies use laboratory testing to
determine the internal friction angle and cohesion of collected samples. When assessing the safety of slope failures, the Coulomb
failure criterion is typically employed. Mitigation measures for volcanic hazards like pyroclastic flow or lahar should consider
their runout distance and treat them as density flows. The balance between air or water content, friction, and turbulent dissipation
associated with particle collisions (i.e., particle-fluid interaction) also influences the velocity, runout distance, and deposition
morphology of friction flows. Taking these factors into account, it is crucial to evaluate the various physical properties related to
'friction' to prepare for volcanic hazards.
