Magnetic configuration of the corona before relaxation. Top: characteristic field lines that highlight the main magnetic topological structures and connectivity domains of the corona (see Sect. 2.4). Blue lines are open field lines, green lines are field lines closed under the pseudo-streamer dome, and red and yellow lines are trans-equatorial closed field lines. The purple lines show the spines from all three null points, which are labeled NP. Bottom: initial distribution of Q, the squashing factor, in logarithmic scale on the solar surface at initial time (see Sect. 2.4).