Fig. 5
Strength profile models of present-day Mars. Strength in the brittle deformation region was calculated by using Byerlee’s law (Byerlee 1978). The dashed line labeled SAF shows the frictional strength of the San Andreas Fault, for which µ = 0.15 (Lockner et al. 2011). The Peierls mechanism, power-law creep, and diffusion creep (grain boundary diffusion) were applied to calculate the strength of minerals at each depth in the region of ductile deformation. The flow law of plagioclase (Shelton 1981; Rybacki and Dresen 2000; Azuma et al. 2014) was used for the crust, and the flow law of olivine (Evans and Goetze 1979; Karato and Wu 1993; Karato and Jung 2003; Hirth and Kohlstedt 2003; Katayama and Karato 2008) was applied for the mantle. The strain rates were assumed to be 10−14 s−1 (solid line) and 10−16 s−1 (dashed line) for the North Pole (Laskar et al. 2004), and strain rates of 10−16 (solid line) and 10−19 s−1 (dashed line) were adopted for Solis Planum (McGovern et al. 2004; Ruiz et al. 2006). The parameters used are summarized in Table 3; the rheological structure for both dry and wet rheologies is shown. a Strength profile models for the Martian lowlands (North Pole). The Moho depth was assumed to be 35 km (Phillips et al. 2008). b Strength profile models of the Martian highlands (Solis Planum). The Moho depth was assumed to be 65 km (Neumann et al. 2004)