= Solution
The offset layered sequence indicates \b[reverse slip on the west-dipping <fault>]: its western <hanging wall> moved up relative to the eastern <footwall>. With the <fault strike> perpendicular to the east–west image plane, an <Andersonian faulting regime> has $\sigma_1$ horizontal east–west, $\sigma_2$ horizontal north–south, and $\sigma_3$ vertical. Draw opposing compression arrows east–west and a smaller opposing pair vertically; the intermediate pair points into and out of the page.
For example, in east, north, up coordinates, a compression-positive <effective stress> tensor consistent with a $30^\circ$ <reverse fault> and zero <cohesion> is
$$
\boldsymbol\sigma'=\begin{pmatrix}90&0&0\\0&60&0\\0&0&30\end{pmatrix}\ \mathrm{MPa}.
$$
These magnitudes illustrate one possible <stress tensor>, rather than a measurement from the photograph. With $\mu=1/\sqrt3$, the $\sigma_1$–$\sigma_3$ <Mohr circle> is tangent to the <Mohr-Coulomb failure criterion> at a plane $30^\circ$ from horizontal. The original failure-mechanics figure above sketches these <principal stress> directions.
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