# The Hazard Library
# Copyright (C) 2012-2020 GEM Foundation
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
Module :mod:`openquake.hazardlib.source.simple_fault` defines
:class:`SimpleFaultSource`.
"""
import copy
import math
from openquake.baselib.python3compat import round
from openquake.hazardlib import mfd
from openquake.hazardlib.source.base import ParametricSeismicSource
from openquake.hazardlib.geo.surface.simple_fault import SimpleFaultSurface
from openquake.hazardlib.geo.nodalplane import NodalPlane
from openquake.hazardlib.source.rupture import ParametricProbabilisticRupture
[docs]class SimpleFaultSource(ParametricSeismicSource):
"""
Simple fault source typology represents seismicity occurring on a fault
surface with simple geometry.
:param upper_seismogenic_depth:
Minimum depth an earthquake rupture can reach, in km.
:param lower_seismogenic_depth:
Maximum depth an earthquake rupture can reach, in km.
:param fault_trace:
A :class:`~openquake.hazardlib.geo.line.Line` representing
the line of intersection between the fault plane and the Earth's
surface.
:param dip:
Angle between earth surface and fault plane in decimal degrees.
:param rake:
the direction of hanging wall relative to the foot wall.
:param rupture_slip_direction:
Angle describing rupture propagation direction in decimal degrees.
:param hypo_list:
Array describing the relative position of the hypocentre on the rupture
surface. Each line represents a hypocentral position defined in terms
of the relative distance along strike and dip (from the upper, left
corner of the fault surface i.e. the corner which results from the
projection at depth of the first vertex of the fault trace) and the
corresponding weight. Example 1: one single hypocentral position at the
center of the rupture will be described by the following
array[(0.5, 0.5, 1.0)]. Example 2: two possible hypocenters are
admitted for a rupture. One hypocentre is located along the strike at
1/4 of the fault length and at 1/4 of the fault width along the dip and
occurs with a weight of 0.3, the other one is at 3/4 of fault length
along strike and at 3/4 of fault width along strike with a weight of
0.7. The numpy array would be entered as numpy.array([[0.25, 0.25, 0.3],
[0.75, 0.75, 0.7]]).
:param slip_list:
Array describing the rupture slip direction, which desribes the rupture
propagation direction on the rupture surface. Each line represents a
rupture slip direction and the corresponding weight. Example 1: one
single rupture slip direction with angle 90 degree will be described
by the following array[(90, 1.0)]. Example 2: two possible rupture slip
directions are admitted for a rupture. One slip direction is at 90
degree with a weight of 0.7, the other one is at 135 degree with a
weight of 0.3. The numpy array would be entered as numpy.array(
[[90, 0.7], [135, 0.3]]).
See also :class:`openquake.hazardlib.source.base.ParametricSeismicSource`
for description of other parameters.
:raises ValueError:
If :meth:`~openquake.hazardlib.geo.surface.simple_fault.SimpleFaultSurface.check_fault_data`
fails, if rake value is invalid and if rupture mesh spacing is too high
for the lowest magnitude value.
"""
code = b'S'
MODIFICATIONS = {'set_geometry', 'adjust_dip', 'set_dip'}
def __init__(self, source_id, name, tectonic_region_type,
mfd, rupture_mesh_spacing,
magnitude_scaling_relationship, rupture_aspect_ratio,
temporal_occurrence_model,
# simple fault specific parameters
upper_seismogenic_depth, lower_seismogenic_depth,
fault_trace, dip, rake, hypo_list=(), slip_list=()):
super().__init__(
source_id, name, tectonic_region_type, mfd, rupture_mesh_spacing,
magnitude_scaling_relationship, rupture_aspect_ratio,
temporal_occurrence_model)
NodalPlane.check_rake(rake)
SimpleFaultSurface.check_fault_data(
fault_trace, upper_seismogenic_depth, lower_seismogenic_depth,
dip, rupture_mesh_spacing)
self.fault_trace = fault_trace
self.upper_seismogenic_depth = upper_seismogenic_depth
self.lower_seismogenic_depth = lower_seismogenic_depth
self.dip = dip
self.rake = rake
min_mag, max_mag = self.mfd.get_min_max_mag()
cols_rows = self._get_rupture_dimensions(float('inf'), float('inf'),
min_mag)
self.slip_list = slip_list
self.hypo_list = hypo_list
if (len(self.hypo_list) and not len(self.slip_list) or
not len(self.hypo_list) and len(self.slip_list)):
raise ValueError('hypo_list and slip_list have to be both given '
'or neither given')
if 1 in cols_rows:
raise ValueError('mesh spacing %s is too high to represent '
'ruptures of magnitude %s' %
(rupture_mesh_spacing, min_mag))
[docs] def iter_ruptures(self, **kwargs):
"""
See :meth:
`openquake.hazardlib.source.base.BaseSeismicSource.iter_ruptures`.
Generates a ruptures using the "floating" algorithm: for all the
magnitude values of assigned MFD calculates the rupture size with
respect to MSR and aspect ratio and then places ruptures of that
size on the surface of the whole fault source. The occurrence
rate of each of those ruptures is the magnitude occurrence rate
divided by the number of ruptures that can be placed in a fault.
"""
whole_fault_surface = SimpleFaultSurface.from_fault_data(
self.fault_trace, self.upper_seismogenic_depth,
self.lower_seismogenic_depth, self.dip, self.rupture_mesh_spacing)
whole_fault_mesh = whole_fault_surface.mesh
mesh_rows, mesh_cols = whole_fault_mesh.shape
fault_length = float((mesh_cols - 1) * self.rupture_mesh_spacing)
fault_width = float((mesh_rows - 1) * self.rupture_mesh_spacing)
for mag, mag_occ_rate in self.get_annual_occurrence_rates():
rup_cols, rup_rows = self._get_rupture_dimensions(
fault_length, fault_width, mag)
num_rup_along_length = mesh_cols - rup_cols + 1
num_rup_along_width = mesh_rows - rup_rows + 1
num_rup = num_rup_along_length * num_rup_along_width
occurrence_rate = mag_occ_rate / float(num_rup)
for first_row in range(num_rup_along_width):
for first_col in range(num_rup_along_length):
mesh = whole_fault_mesh[first_row: first_row + rup_rows,
first_col: first_col + rup_cols]
if not len(self.hypo_list) and not len(self.slip_list):
hypocenter = mesh.get_middle_point()
occurrence_rate_hypo = occurrence_rate
surface = SimpleFaultSurface(mesh)
yield ParametricProbabilisticRupture(
mag, self.rake, self.tectonic_region_type,
hypocenter, surface, occurrence_rate_hypo,
self.temporal_occurrence_model)
else:
for hypo in self.hypo_list:
for slip in self.slip_list:
surface = SimpleFaultSurface(mesh)
hypocenter = surface.get_hypo_location(
self.rupture_mesh_spacing, hypo[:2])
occurrence_rate_hypo = occurrence_rate * \
hypo[2] * slip[1]
rupture_slip_direction = slip[0]
yield ParametricProbabilisticRupture(
mag, self.rake, self.tectonic_region_type,
hypocenter, surface, occurrence_rate_hypo,
self.temporal_occurrence_model,
rupture_slip_direction)
[docs] def count_ruptures(self):
"""
See :meth:
`openquake.hazardlib.source.base.BaseSeismicSource.count_ruptures`.
"""
whole_fault_surface = SimpleFaultSurface.from_fault_data(
self.fault_trace, self.upper_seismogenic_depth,
self.lower_seismogenic_depth, self.dip, self.rupture_mesh_spacing)
whole_fault_mesh = whole_fault_surface.mesh
mesh_rows, mesh_cols = whole_fault_mesh.shape
fault_length = float((mesh_cols - 1) * self.rupture_mesh_spacing)
fault_width = float((mesh_rows - 1) * self.rupture_mesh_spacing)
self._nr = []
n_hypo = len(self.hypo_list) or 1
n_slip = len(self.slip_list) or 1
for (mag, mag_occ_rate) in self.get_annual_occurrence_rates():
if mag_occ_rate == 0:
continue
rup_cols, rup_rows = self._get_rupture_dimensions(
fault_length, fault_width, mag)
num_rup_along_length = mesh_cols - rup_cols + 1
num_rup_along_width = mesh_rows - rup_rows + 1
self._nr.append(num_rup_along_length * num_rup_along_width *
n_hypo * n_slip)
counts = sum(self._nr)
return counts
def _get_rupture_dimensions(self, fault_length, fault_width, mag):
"""
Calculate rupture dimensions for a given magnitude.
:param fault_length:
The length of the fault as a sum of all segments, in km.
:param fault_width:
The width of the fault, in km.
:param mag:
Magnitude value to calculate rupture geometry for.
:returns:
A tuple of two integer items, representing rupture's dimensions:
number of mesh points along length and along width respectively.
The rupture is reshaped (conserving area, if possible) if one
of dimensions exceeds fault geometry. If both do, the rupture
is considered to cover the whole fault.
"""
area = self.magnitude_scaling_relationship.get_median_area(
mag, self.rake)
rup_length = math.sqrt(area * self.rupture_aspect_ratio)
rup_width = area / rup_length
# clip rupture's length and width to fault's length and width
# if there is no way to fit the rupture otherwise
if area >= fault_length * fault_width:
rup_length = fault_length
rup_width = fault_width
# reshape rupture (conserving area) if its length or width
# exceeds fault's length or width
elif rup_width > fault_width:
rup_length = rup_length * (rup_width / fault_width)
rup_width = fault_width
elif rup_length > fault_length:
rup_width = rup_width * (rup_length / fault_length)
rup_length = fault_length
# round rupture dimensions with respect to mesh_spacing
# and compute number of points in the rupture along length
# and width (aka strike and dip)
rup_cols = int(round(rup_length / self.rupture_mesh_spacing) + 1)
rup_rows = int(round(rup_width / self.rupture_mesh_spacing) + 1)
return rup_cols, rup_rows
[docs] def modify_set_geometry(self, fault_trace, upper_seismogenic_depth,
lower_seismogenic_depth, dip, spacing):
"""
Modifies the current source geometry including trace, seismogenic
depths and dip
"""
# Check the new geometries are valid
SimpleFaultSurface.check_fault_data(
fault_trace, upper_seismogenic_depth, lower_seismogenic_depth,
dip, spacing
)
self.fault_trace = fault_trace
self.upper_seismogenic_depth = upper_seismogenic_depth
self.lower_seismogenic_depth = lower_seismogenic_depth
self.dip = dip
self.rupture_mesh_spacing = spacing
[docs] def modify_adjust_dip(self, increment):
"""
Modifies the dip by an incremental value
:param float increment:
Value by which to increase or decrease the dip (the resulting
dip must still be within 0.0 to 90.0 degrees)
"""
SimpleFaultSurface.check_fault_data(
self.fault_trace, self.upper_seismogenic_depth,
self.lower_seismogenic_depth, self.dip + increment,
self.rupture_mesh_spacing)
self.dip += increment
[docs] def modify_set_dip(self, dip):
"""
Modifies the dip to the specified value
:param float dip:
New value of dip (must still be within 0.0 to 90.0 degrees)
"""
SimpleFaultSurface.check_fault_data(
self.fault_trace, self.upper_seismogenic_depth,
self.lower_seismogenic_depth, dip, self.rupture_mesh_spacing)
self.dip = dip
def __iter__(self):
mag_rates = self.get_annual_occurrence_rates()
if len(mag_rates) == 1: # not splittable
yield self
return
for i, (mag, rate) in enumerate(mag_rates):
src = copy.copy(self)
del src._nr
src.mfd = mfd.ArbitraryMFD([mag], [rate])
src.num_ruptures = self._nr[i]
yield src
@property
def polygon(self):
"""
The underlying polygon
`"""
return SimpleFaultSurface.surface_projection_from_fault_data(
self.fault_trace, self.upper_seismogenic_depth,
self.lower_seismogenic_depth, self.dip)
[docs] def wkt(self):
"""
:returns: the geometry as a WKT string
"""
return self.polygon.wkt