3.1.5. Basal Heat Flow

The basal heat flow, which is the heat sourced from the mantle, transferred through the basin and constitutes the lower boundary condition in the models, is so far kept constant at 47 mW·m<sup>−</sup>2. This basal heat flow value is slightly above one heat flow unit and is typical for some continental shelves, e.g., parts of the Norwegian Continental Shelf. However, to study the influence of the basal heat flow on the temperature development in the basin, three additional values were tested: 40 mW·m<sup>−</sup>2, 60 mW·m<sup>−</sup>2, and 80 mW·m<sup>−</sup><sup>2</sup> (Table 1). Figure 13b shows the results for 40 and 80 mW·m<sup>−</sup><sup>2</sup> together with the default heat flow (47 mW·m<sup>−</sup>2). Increased heat flow leads to higher steady-state temperatures and longer time is therefore needed for the basin to regain steady state (Figure 13b). The resulting transient temperatures of basins modeled with 80 mW·m<sup>−</sup><sup>2</sup> and 40 mW·m<sup>−</sup><sup>2</sup> show thermal di fferences up to 140 ◦C (Figure 13a). For the tested values, the models regain steady state approximately between 9 and 12 Myr after the fault slip. Increasing basal heat flow gives higher temperatures in the basin, and as a consequence, a longer time is needed for the basin to arrive at steady state after fault slip.

**Figure 13.** (**a**) Thermal di fference between transient temperatures in basin with basal heat flow of 80 mW·m<sup>−</sup>2, to basin with basal heat flow of 40 mW·m<sup>−</sup><sup>2</sup> at 10 kyr after fault slip. (**b**) Results show the temperatures for the default and the two extreme values for heat flow: 47 mW·m<sup>−</sup>2, 40 mW·m<sup>−</sup>2, and 80 mW·m<sup>−</sup>2. Location of studied point is indicated in Figure 8b.
