A mechanism for the formation of large icebergs

Publisher Website
Google Scholar
Abstract
The calving of floating glaciers to form icebergs is a major form of ice loss from the Antarctic ice sheet. Disintegration of massive, unconfined, seaward extending ice shelves or glacier tongues gives rise to the largest type of iceberg, some of which have horizontal dimensions exceeding 100 km. Several ice tongues are known to exhibit a quasi‐cyclic pattern of calving and subsequent regrowth. A mechanism that would seem to explain this type of calving behavior is based on the vibrational characteristics of the system of a buoyant ice plate floating in shallow water. Ocean wave energy, responsible for the motion, is intercepted by the glacier, either directly from open ocean or after transmission through, and subsequent filtering by, sea ice. The glacier also acts as a wave filter, with filtering characteristics depending on the ice thickness. When a dominant frequency occurring in the incident wave spectrum coincides with one of the natural frequencies of the glacier, then a resonant motion will occur. For relatively high modes of oscillation, low level, but sustained cyclic bending stresses may lead to crack propagation and subsequent fatigue failure in the ice. The contribution of other mechanisms which induce tensile stresses in the ice are considered to be very important in an overall view of the calving problem, and some of these mechanisms are discussed in relation to the vibration mechanism. It is possible to view the proposed vibration mechanism as a trigger which raises the resultant stresses in the ice to the point where fracture will occur.

This publication has 18 references indexed in Scilit: