rsqsim_api.fault.splines

Spline utilities for constructing idealised slip distributions on fault patches.

Provides functions that build scipy.interpolate.UnivariateSpline objects encoding along-fault and depth-dependent slip profiles, suitable for imposing prescribed slip distributions in RSQSim or other fault models.

Functions

fault_edge_spline(max_slip, distance_width, total_width)	Build a univariate spline encoding slip as a function of along-fault distance.
fault_depth_spline(gradient_change_x, after_change_fract)	Build a univariate spline encoding normalised slip as a function of normalised depth.

Module Contents

rsqsim_api.fault.splines.fault_edge_spline(max_slip, distance_width, total_width, min_slip_fraction=0.0, line_stop_fraction=0.5, gradient_change=1.2, spline_k=3, spline_s=0.0, resolution=10.0)

Build a univariate spline encoding slip as a function of along-fault distance.

Constructs an interpolated spline that ramps from a minimum slip fraction at the fault edge up to the maximum slip, with a piecewise-linear interpolant shaped by the supplied parameters.

Parameters:

• max_slip (float) – Maximum slip value (m or m/yr) at the centre of the fault.

• distance_width (float) – Along-fault distance (m) at which max_slip is reached.

• total_width (float) – Total along-fault width (m) of the spline domain.

• min_slip_fraction (float, optional) – Fraction of max_slip at the fault edge (distance = 0). Defaults to 0.

• line_stop_fraction (float, optional) – Fraction of distance_width at which the initial ramp levels off before the gradient change. Defaults to 0.5.

• gradient_change (float, optional) – Multiplicative factor applied to the intermediate y value to create a smooth overshoot before the final ramp. Defaults to 1.2.

• spline_k (int, optional) – Degree of the smoothing spline. Defaults to 3 (cubic).

• spline_s (float, optional) – Smoothing factor passed to UnivariateSpline. Defaults to 0.0 (interpolating spline).

• resolution (float, optional) – Sample spacing (m) used when building the x-axis for interpolation. Defaults to 10.

Returns:

Spline object; call with an x array (metres from edge) to evaluate the slip profile.

Return type:

scipy.interpolate.UnivariateSpline

rsqsim_api.fault.splines.fault_depth_spline(gradient_change_x, after_change_fract, resolution=0.01, after_change_gradient=1.2, spline_k=3, spline_s=0.0)

Build a univariate spline encoding normalised slip as a function of normalised depth.

Produces a spline on [0, 1] (normalised depth fraction) that is approximately flat at 1 down to gradient_change_x, then ramps linearly to 0 at the base of the fault, with an optional gradient overshoot controlled by after_change_gradient.

Parameters:

• gradient_change_x (float) – Normalised depth (0–1) at which the gradient begins to change.

• after_change_fract (float) – Fraction of the remaining depth below gradient_change_x over which the gradient change is applied.

• resolution (float, optional) – Sample spacing in normalised depth used when building the spline. Defaults to 0.01.

• after_change_gradient (float, optional) – Multiplicative factor that controls the magnitude of the gradient overshoot. Defaults to 1.2.

• spline_k (int, optional) – Degree of the smoothing spline. Defaults to 3 (cubic).

• spline_s (float, optional) – Smoothing factor passed to UnivariateSpline. Defaults to 0.0 (interpolating spline).

Returns:

Spline object; call with a normalised-depth array to evaluate the depth-dependent slip multiplier.

Return type:

scipy.interpolate.UnivariateSpline