Figure 3.

(a) Normal stress changes (Δσ_n; bar, fault unclamping positive) created by the 2012 Costa Rica and 1992 Nicaragua earthquakes (finite fault models from Hayes^34,36; symbols are as those in Fig. 2); see also Fig. S2 and Supporting Information. Small yellow circles indicate different types of seafloor methane seeps (after Ranero et al.¹⁸ and Kluesner et al.²²). (b,c) Vertical cross sections of normal stress changes superposed onto the Costa Rica¹⁸ and Nicaragua³³ wedges (sedimentary wedge in gray shading). The emitted fluids are inferred to travel upward along normal faults rooted in the subduction interface, and thus stress changes are resolved on seaward-dipping normal faults (strike = 132°, dip = 60°, rake = −90°). A convenient range of stress change values (−5, 5 bar) has been arbitrarily chosen; note that in some models the calculated stresses may exceed this range. In horizontal section a stress is sampled at 5 km depth (dashed blue line in vertical cross sections b and c). This figure was generated using the Coulomb 3.4 software (https://earthquake.usgs.gov/research/software/coulomb) and Adobe Illustrator CS3 (https://www.adobe.com).