Electronic Supplement to : Low friction along the high slip patch of the 2011 Mw 9 . 0 Tohoku - Oki earthquake

The objective of this Electronic Supplement is to present in a concise manner the kinematic approach of limit analysis for fluid saturated media as proposed in details by Leroy and Pons (2012). The limit analysis approach [Chandrasekharaiah and Debnath, 1994; Salençon, 2002] is based on the principle of virtual powers and the theorem of maximum rock strength [Maillot and Leroy, 2006]. The method investigates all possible collapse mechanisms as a function of the frictional properties and selects the optimal one leading to the least upper bound to the tectonic force. The method has previously been applied to retrieve frictional properties of accretionary prism faults [Cubas et al., 2008; Souloumiac et al., 2009; Pons et al., 2013; Cubas et al., subm.a] and has been validated quantitatively from comparison with analogue sandbox experiments [Cubas et al., subm.b]. In this study, the Coulomb criterion is used for the maximum rock strength. The upper bounds to the tectonic force for two of the collapse mechanisms used in the main text are presented.