def backslip_params(azimuth, strike, dip, amplitude, locking_depth):
"""
Transforms the interseismic blockmodel parameters to fault input parameters
for the backslip model.
Parameters
----------
azimuth : float
azimuth [deg] of the block-motion towards the North
strike : float
strike-angle[deg] of the backslipping fault
dip : float
dip-angle[deg] of the back-slipping fault
amplitude : float
slip rate of the blockmodel [m/yr]
locking_depth : float
locking depth [km] of the fault
Returns
-------
dict of parameters for the back-slipping RectangularSource
"""
if dip == 0.:
raise ValueError('Dip must not be zero!')
az_vec = utility.strike_vector(azimuth)
strike_vec = utility.strike_vector(strike)
alpha = num.arccos(az_vec.dot(strike_vec))
alphad = alpha * r2d
sdip = num.sin(dip * d2r)
# assuming dip-slip is zero --> strike slip = slip
slip = num.abs(amplitude * num.cos(alpha))
opening = -amplitude * num.sin(alpha) * sdip
if alphad < 90. and alphad >= 0.:
rake = 0.
elif alphad >= 90. and alphad <= 180.:
rake = 180.
else:
raise Exception('Angle between vectors inconsistent!')
width = locking_depth * km / sdip
return dict(slip=float(slip),
opening=float(opening),
width=float(width),
depth=0.,
rake=float(rake))
def block_movement(bmask, amplitude, azimuth):
"""
Get block movements. Assumes one side of the model stable, therefore
the moving side is moving 2 times the given amplitude.
Parameters
----------
bmask : :class:`numpy.ndarray`
masked block determining stable and moving observation points
amplitude : float
slip [m] of the moving block
azimuth : float
azimuth-angle[deg] ergo direction of moving block towards North
Returns
-------
:class:`numpy.ndarray`
(n x 3) [North, East, Down] displacements [m]
"""
tmp = num.repeat(bmask * 2. * float(amplitude), 3).reshape(
(bmask.shape[0], 3))
sv = utility.strike_vector(float(azimuth), order='NEZ')
return tmp * sv