J. N. Hutchinson writes: The mass movement in Cortina d'Ampezzo studied by Angeli et al. (1996), with a length of about 1000 m, a thickness of around 5 m and an average width of 80m (Deganutti & Gasparetto 1992), is a typical elongate mudslide (Hutchinson 1988). Such mudslides are strongly three-dimensional and their stability analyses need to reflect this. The otherwise interesting study by Angeli et al. of the movements of this mudslide is marred by their treatment of it as a two-dimensional infinite slope. It is hoped that, in their reply, the authors will make the appropriate modifications to their calculations and conclusions.

Maceo-Giovanni Angeli replies: The authors are grateful for Professor Hutchinson's interest in their paper.

Since the Alvera mudslide is relatively wide (80 m) in comparison to its depth (5 m) the influence of side shear on the overall stability will be slight and side shear effects have been neglected in the development of the equations presented in the paper. In fact, due to the increase in shearing resistance with depth, a unit area of the base contributes much more to total shearing resistance made than a unit area of the sides. A consideration of the restraining forces acting on a 1m length of the base and sides of the mudflow shows this to be the case.

The actual cross-sectional shape of the slip surface has not been determined in detail, although survey measurements indicate that, as in the case of Hutchinson's (1970) work at Beltinge, the

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