rsqsim_api.fault.slip

Hikurangi subduction zone slip-rate and coupling utilities.

Provides helper functions for computing along-trench distances, coupling coefficients, and convergence rates for the Hikurangi margin, as well as a general best-fit-plane routine.

Attributes

`transformer`
`trans_inv`
`east_cape`
`start_0_2`
`end_0_2`
`start_0_5`
`convergence_start`
`convergence_end`
`east_cape_dist`
`start_0_2_dist`
`end_0_2_dist`
`start_0_5_dist`
`convergence_start_dist`
`convergence_end_dist`

Functions

`fit_plane_to_points`(points[, eps])	Fit a best-fit plane to a set of 3-D points using SVD.
`point_dist`(point, along_overall)	Project a WGS84 point onto an NZTM direction vector.
`point_dist_nztm`(point, along_overall)	Project an NZTM point onto a direction vector.
`coupling`(dist)	Return the Hikurangi plate-interface coupling coefficient at a given along-trench distance.
`convergence`(dist)	Return the Hikurangi convergence rate at a given along-trench distance.
`convergence_dist`(dist)
`kermadec_slip_rate`(dist[, modelled_value])	Compute the Kermadec subduction zone slip rate at a given along-trench distance.

Module Contents

rsqsim_api.fault.slip.transformer[source]

rsqsim_api.fault.slip.trans_inv[source]

rsqsim_api.fault.slip.fit_plane_to_points(points, eps=1e-05)[source]

Fit a best-fit plane to a set of 3-D points using SVD.

The plane is constrained to pass through the centroid of the point cloud. The normal is extracted from the last column of the left singular matrix of the de-meaned covariance and is oriented so that its z-component is positive.

Parameters:

points (numpy.ndarray of shape (n, 3)) – Array of 3-D point coordinates.
eps (float, optional) – Threshold below which normal-vector components are set to exactly zero. Defaults to 1e-5.

Returns:

plane_normal (numpy.ndarray of shape (3,)) – Unit normal vector to the best-fit plane (A, B, C).
plane_origin (numpy.ndarray of shape (3,)) – Centroid of the input points, lying on the fitted plane.

rsqsim_api.fault.slip.east_cape[source]

rsqsim_api.fault.slip.start_0_2[source]

rsqsim_api.fault.slip.end_0_2[source]

rsqsim_api.fault.slip.start_0_5[source]

rsqsim_api.fault.slip.convergence_start[source]

rsqsim_api.fault.slip.convergence_end[source]

rsqsim_api.fault.slip.point_dist(point, along_overall)[source]

Project a WGS84 point onto an NZTM direction vector.

Transforms the point to NZTM (EPSG:2193) and computes its dot product with the supplied unit direction vector.

Parameters:

point (shapely.geometry.Point) – Point in WGS84 (longitude, latitude) coordinates.
along_overall (numpy.ndarray of shape (2,)) – 2-D unit direction vector in NZTM coordinates.

Returns:

Scalar projection of the transformed point onto along_overall.

Return type:

float

rsqsim_api.fault.slip.point_dist_nztm(point, along_overall)[source]

Project an NZTM point onto a direction vector.

Parameters:

point (shapely.geometry.Point) – Point already in NZTM (EPSG:2193) coordinates.
along_overall (numpy.ndarray of shape (2,)) – 2-D unit direction vector.

Returns:

Scalar projection of the point onto along_overall.

Return type:

float

rsqsim_api.fault.slip.east_cape_dist[source]

rsqsim_api.fault.slip.start_0_2_dist[source]

rsqsim_api.fault.slip.end_0_2_dist[source]

rsqsim_api.fault.slip.start_0_5_dist[source]

rsqsim_api.fault.slip.convergence_start_dist[source]

rsqsim_api.fault.slip.convergence_end_dist[source]

rsqsim_api.fault.slip.coupling(dist)[source]

Return the Hikurangi plate-interface coupling coefficient at a given along-trench distance.

Implements a piecewise model: 0.2 south of start_0_2, 0.5 north of start_0_5, and a linear gradient in between.

Parameters:: dist (float) – Along-trench distance (m in NZTM projection) from east cape.
Returns:: Coupling coefficient (dimensionless, 0–1).
Return type:: float
Raises:: AssertionError – If dist is south of east cape (i.e. less than east_cape_dist).

rsqsim_api.fault.slip.convergence(dist)[source]

Return the Hikurangi convergence rate at a given along-trench distance.

Linear interpolation between 49 mm/yr at the southern end (convergence_start) and 85 mm/yr at the northern end (convergence_end).

Parameters:: dist (float) – Along-trench distance (m in NZTM projection).
Returns:: Convergence rate in mm/yr.
Return type:: float

rsqsim_api.fault.slip.convergence_dist(dist)[source]

rsqsim_api.fault.slip.kermadec_slip_rate(dist, modelled_value=0.0)[source]

Compute the Kermadec subduction zone slip rate at a given along-trench distance.

Blends the modelled slip rate with the convergence-rate-based estimate using a linear fractional interpolation from east cape to the 0.2-coupling start point. If modelled_value is zero, returns the pure convergence × coupling estimate.

Parameters:

dist (float) – Along-trench distance (m in NZTM projection).
modelled_value (float, optional) – Modelled slip rate (mm/yr) from the fault model. If 0 (default), only coupling × convergence is used.

Returns:

Slip rate in mm/yr.

Return type:

float