The critical fracture toughness is a material parameter describing the resistance of a cracked body to further crack extension. It is an important parameter to simulate and predict the break-up behaviour of ice shelves from calving of single icebergs to the disintegration of entire ice shelves over a wide range of length scales. The fracture toughness values are calculated with equations that are derived from an elastic stress analysis. Additionally, an X-ray computer tomography (CT scanner) was used to identify the density as a function of depth. The critical fracture toughness of 91 Antarctic inland ice samples with densities between 840 to 870 kg/m**3 has been determined by applying a four-point-bending technique on single edge v-notched beam samples. The examined ice core was drilled 70m north of Kohnen Station, Dronnning Maud Land (75°00' S, 00°04' E, 2882 m).

Method of measurements of fracture toughness follows ASTM C1421-01b: Standard test methods for determination of fracture toughness of advanced ceramics at ambient temperature (http://www.astm.org/DATABASE.CART/HISTORICAL/C1421-01B.htm) and ASTM E1820-08: Standard test methods for measurement of fracture toughness (http://www.astm.org/DATABASE.CART/HISTORICAL/E1820-08.htm).

Supplement to: Christmann, Julia; Müller, Ralf; Webber, Kyle G; Isaia, Daniel; Schader, Florian H; Kipfstuhl, Sepp; Freitag, Johannes; Humbert, Angelika (2015): Measurement of the fracture toughness of polycrystalline bubbly ice from an Antarctic ice core. Earth System Science Data, 7(1), 87-92