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Reassessing rock mass properties and slope instability triggering conditions in Valles Marineris, Mars

Lookup NU author(s): Professor Stefano Utili

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Abstract

The rock walls of the Valles Marineris valleys (VM) in the equatorial area of Mars exhibit severalgravitational failures which resulted in a series of large landslides up to several hundred cubic kilometersin volume. Questions arise as to forces at play and rock strength in the stability of the walls of VM.In this work we address the stability analysis of the walls of VM by considering the strength of thematerials of the walls and the causes of landslides. Using finite element calculations and the limitanalysis upper bound method, we explore the range of cohesion and friction angle values associatedwith realistic failure geometries, and compare predictions with the more classical Culmann’s translationalfailure model. Our analysis is based both on synthetic, simplified slope profiles, and on the real shape ofthe walls of VM taken from the MOLA topographic data. Validation of the calibrated cohesion and frictionangle values is performed by comparing the computed unstable cross sectional areas with the observedpre- and post-failure profiles, the estimated failure surface geometry and ridge crest retreat. This offersa link between rock mass properties, slope geometry and volume of the observed failure, represented indimensionless charts. The role of groundwater flow and seismic action on the decrease of slope stabilityis also estimated. Pseudo-static seismic analyses provide another set of dimensionless charts and showthat low seismicity events induced by meteoroid impacts, consistent with the size of craters, could be acause for some of the observed landslides, if poor rock properties for VM are assumed. Analyses suggestthat rock mass properties are more similar to their earth equivalents with respect to what has beenpreviously supposed.

Publication metadata

Author(s): Crosta GB, Utili S, De Blasio FV, Castellanza R

Publication type: Article

Publication status: Published

Journal: Earth and Planetary Science Letters

Year: 2014

Volume: 388

Pages: 329-342

Print publication date: 15/02/2014

Online publication date: 04/01/2014

Acceptance date: 23/11/2013

ISSN (print): 0012-821X

ISSN (electronic): 1385-013X

Publisher: Elsevier BV

URL: https://doi.org/10.1016/j.epsl.2013.11.053

DOI: 10.1016/j.epsl.2013.11.053

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