3.1.1. Fault Displacement

The original model has a fault displacement of 1200 m with syn-rift deposits of the same thickness and about 600 m of post-rift deposits, taking place over one timestep (Figure1). These post-rift deposits are kept unchanged in all tested scenarios. Additional four fault displacement models were tested; 500 m, 1000 m, 2000 m, and 3000 m (Table 1). As expected, temperature differences across the fault zone increases with the fault displacement. With 3000 m fault slip there is a temperature difference of more than 50 ◦C across the fault zone immediately after fault slip (Figure 6a). In the footwall part, the isotherms make a gentle downward bend towards the fault zone. As time passes, a gradual heating of the sediments in the hanging wall section occurs and the bend of the isotherms from the footwall side ties with those of the hanging wall (~10 kyr after faulting) creating continuous isotherms (Figure 6b,c). There is also a slight temperature change in the footwall part due to the deposition of cold post-rift sediments over that area.

**Figure 6.** Temperature development in a basin with 3000 m fault slip: temperatures at 1 kyr (**a**), 500 kyr (**b**), and 5 Myr (**c**) after fault slip.

With increasing fault slip but within the same timeframe, the volume of deposited sediments and time needed for basin to regain steady state increases. For the modeled basin with 500 m of fault slip, large parts of the basin differ ~20 ◦C from the steady state basin 10 kyr after displacement (Figure 7a). Around 9 Myr later the basin obtains steady state. When fault displacement is 3000 m, large parts of the hanging wall section differ more than 50 ◦C from the steady state basin at 10 kyr after fault slip (Figure 7b). Steady state is achieved approximately 11 Myr after fault slip. As expected a basin with larger fault slip and higher influx of sediments requires more time to regain steady state, compared to a basin with smaller fault slip and less sediment deposits.

**Figure 7.** Temperature difference between steady state and transient temperatures for fault slip of 500 m (**a**) and 3000 m (**b**) at 10 kyr after fault slip.

### 3.1.2. Time Span of Faulting and Deposition

So far the modeling assumes the fault slip to be almost instantaneous (taking place over 10 kyr). The next set of models explores four different time spans of faulting and deposition of the same amount of sediments: 1, 5, 10, and 20 Myr. The results show that slower faulting and deposition rates, as expected, keep the basin closer to a steady-state condition compared to high rates (Figure 8a,b). Adding 10 Myr to the faulting and deposition time results in a basin with transient temperatures much closer to those of steady state throughout the whole period. For a faulting and deposition rate over 20 Myr, the basin is never in a state of thermal instability. The resulting trend show that basins with the same amount of sediment input and faulting and deposition time up to 10 Myr regains steady state approximately 10 Myr after faulting initiated (Figure 8c). This means that from time of faulting and deposition to the process is finalized, more time is required for a basin with rapid fault slip and deposition to regain steady state compared to a basin with slow fault slip and deposition. It emphasizes how crucial the time relation is for faulting and deposition and basin's thermal development after fault slip.

**Figure 8.** (**a**) Temperature difference between steady state and transient temperatures with fault slip and deposition over 10 kyr. (**b**) Temperature difference between steady state and transient temperature with fault slip and deposition over 1 Myr. Temperatures in (**<sup>a</sup>**,**b**) are from the same timestep, 10 kyr and 1.01 Myr respectively after faulting started. The red point in (**b**) indicates location of point plot in (**c**). (**c**) Resulting temperatures for four tested time spans of deposition of syn- and post-rift sediments.
