# The Hazard Library
# Copyright (C) 2013-2018 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.characteristic` defines
:class:`CharacteristicFaultSource`.
"""
import numpy
from openquake.hazardlib.source.base import ParametricSeismicSource
from openquake.hazardlib.geo import mesh, NodalPlane
from openquake.hazardlib.source.rupture import ParametricProbabilisticRupture
from openquake.baselib.slots import with_slots
from openquake.hazardlib.geo.utils import angular_distance, KM_TO_DEGREES
[docs]@with_slots
class CharacteristicFaultSource(ParametricSeismicSource):
"""
Characteristic source typology represents seismicity occuring on a generic
fault surface with seismic events rupturing the entire fault surface
independently of their magnitude values.
Characteristic source typology can be used to model individual faults
or fault segments that tend to produce essentialy same size earthquakes
(see for instance: Schwartz, D. P., K. J. Coppersmith, Fault behavior and
characteristic earthquakes: Examples from the Wasatch and San Andreas fault
zones, J. Geophys. Res., 89, 5681-5698, 1984)
:param surface:
Fault surface, see :mod:`openquake.hazardlib.geo.surface`.
:param rake:
Angle describing rupture propagation direction in decimal degrees.
See also :class:`openquake.hazardlib.source.base.ParametricSeismicSource`
for description of other parameters.
Note that a ``CharacteristicFaultSource`` does not need any mesh spacing,
magnitude scaling relationship, and aspect ratio, therefore the constructor
sets these parameters to ``None``.
NB: if you want to convert a characteristic source into XML, you must set
its attribute `surface_node` to an explicit representation of the surface
as a LiteralNode object.
"""
_slots_ = ParametricSeismicSource._slots_ + 'surface rake'.split()
MODIFICATIONS = set(('set_geometry',))
def __init__(self, source_id, name, tectonic_region_type,
mfd, temporal_occurrence_model, surface, rake,
surface_node=None):
super().__init__(
source_id, name, tectonic_region_type, mfd, None, None, None,
temporal_occurrence_model)
NodalPlane.check_rake(rake)
self.surface = surface
self.rake = rake
[docs] def get_bounding_box(self, maxdist):
"""
Bounding box containing all points, enlarged by the maximum distance
"""
west, east, north, south = self.surface.get_bounding_box()
a1 = maxdist * KM_TO_DEGREES
a2 = angular_distance(maxdist, north, south)
return west - a2, south - a1, east + a2, north + a1
[docs] def iter_ruptures(self):
"""
See :meth:
`openquake.hazardlib.source.base.BaseSeismicSource.iter_ruptures`.
For each magnitude value in the given MFD, return an earthquake
rupture with a surface always equal to the given surface.
"""
hypocenter = self.surface.get_middle_point()
for mag, occurrence_rate in self.get_annual_occurrence_rates():
yield ParametricProbabilisticRupture(
mag, self.rake, self.tectonic_region_type, hypocenter,
self.surface, occurrence_rate, self.temporal_occurrence_model)
[docs] def count_ruptures(self):
"""
See :meth:
`openquake.hazardlib.source.base.BaseSeismicSource.count_ruptures`.
"""
return len(self.get_annual_occurrence_rates())
[docs] def modify_set_geometry(self, surface, surface_node=None):
"""
Modifies the current fault geometry
:param surface:
Fault surface, see :mod:`openquake.hazardlib.geo.surface`.
:param surface_node:
If needed for export, provide the surface as a LiteralNode object
"""
self.surface = surface
self.surface_node = surface_node
@property
def polygon(self):
"""
The underlying polygon, as a convex hull
"""
return self.surface.mesh.get_convex_hull()