Analytical models of magma chamber stability: An abridged critical review of key concepts

Key aspects that need to be taken into consideration when attempting to establish an elastic model of magma chamber stability, and the various forms in which those parameters have been introduced in analytical models of magma chamber stability are examined in critical form. These aspects include the geometry of the chamber, the relative distance and geometry of an outer boundary, the nature of the surface forces that act on each of those two physical boundaries, the role played by a body force (related to the gravitational attraction) and the fact that such force acts on any imaginary surface within the body of interest, as well as some assumptions concerning the description of the lithostatic stress and the criteria used to determine the conditions of tensile failure of the rock. The examination made here reveals that very often the analytical models include one or more sources of internal inconsistencies that are rooted on the disregard of conditions used by the original elastic models. After reviewing key aspects of elastic models the reader is expected to acquire the tools required to fully appreciate the advantages and limitations of specific chamber models, and to decide which of those models is better suited to solve the particular problem at hand.

► Reasons for internal inconsistencies of analytical models are examined.
► Importance of three dimensional shape of chambers is highlighted.
► The identity of the external boundaries is clarified.
► Assumptions concerning the lithostatic stress are reviewed.
► Criteria for fracturing chambers are also examined in detail.