Controls on the distribution of surge-type glaciers in Svalbard

We analyzed the possible controls on the distribution of surge-type glacier s in Svalbard using multivariate logit models including 504 glaciers and a large number of glacial and geological attributes. Specifically we examined the potential effect of geological boundaries, mass-balance conditions and thermal regime on surging. It was found that long glaciers with relatively steep slopes overlying young fine-grained sedimentary lithologies with ori entations in a broad are clockwise from northwest to southeast are most lik ely to be of surge type. No relation between lithological boundaries and su rge potential could be established. Possible explanations for length being conducive to surging are transport-distance-related substrate properties, d istance-related attenuation of longitudinal stresses and the possible relat ion between thermal regime and glacier size. Analysis of glaciers with reco rded radio-echo sounding reveals that a polythermal regime, accumulation-ar ea ratios close to balance and a large elevation span increase the surge po tential. The logit models also enabled us to detect 19 new surge-type glaci ers, to reclassify six glaciers as normal and to identify unusual surge-typ e glaciers. Our model results suggest that a polythermal regime and fine-gr ained potentially deformable beds are conducive to the surge potential of S valbard glaciers.