English: Schematic illustration of a so-called unequilibrium calving process of a large iceberg (here in the form of top-out calving, i.e. the top of the iceberg rotates (‘capsizes’) away from the glacier front). The force acting on the glacier front (calving-contact force, F_C) in ‘upglacier’ direction and its counterpart acting in ‘downglacier’ direction are thought to be responsible for triggering low-frequency seismic waves (‘glacial earthquakes’). (a) Undisturbed calving. The dashed blue arrow indicates the rotational direction of the iceberg; the double-arrow indicates F_C, all other forces are indicated by simple solid black arrows; x_i and y_i are the coordinates of the center of mass of the iceberg; θ is the angle of rotation. (b) Force vectors acting on the capsizing iceberg (e.g. gravity, buoyancy, fluid resistance). (c) Scenario in (a) extended by the ice mélange which floats in front of the glacier, providing a second contact force.