# Source code for openquake.hmtk.seismicity.declusterer.distance_time_windows

```
# -*- coding: utf-8 -*-
# vim: tabstop=4 shiftwidth=4 softtabstop=4
#
# LICENSE
#
# Copyright (C) 2010-2023 GEM Foundation, G. Weatherill, M. Pagani,
# D. Monelli.
#
# The Hazard Modeller's Toolkit 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.
#
# You should have received a copy of the GNU Affero General Public License
# along with OpenQuake. If not, see <http://www.gnu.org/licenses/>
#
# DISCLAIMER
#
# The software Hazard Modeller's Toolkit (openquake.hmtk) provided herein
# is released as a prototype implementation on behalf of
# scientists and engineers working within the GEM Foundation (Global
# Earthquake Model).
#
# It is distributed for the purpose of open collaboration and in the
# hope that it will be useful to the scientific, engineering, disaster
# risk and software design communities.
#
# The software is NOT distributed as part of GEM’s OpenQuake suite
# (https://www.globalquakemodel.org/tools-products) and must be considered as a
# separate entity. The software provided herein is designed and implemented
# by scientific staff. It is not developed to the design standards, nor
# subject to same level of critical review by professional software
# developers, as GEM’s OpenQuake software suite.
#
# Feedback and contribution to the software is welcome, and can be
# directed to the hazard scientific staff of the GEM Model Facility
# (hazard@globalquakemodel.org).
#
# The Hazard Modeller's Toolkit (openquake.hmtk) is therefore distributed WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
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# The GEM Foundation, and the authors of the software, assume no
# liability for use of the software.
"""
"""
import abc
import numpy as np
from openquake.baselib.general import CallableDict
TIME_DISTANCE_WINDOW_FUNCTIONS = CallableDict()
DAYS = 364.75
[docs]def time_window_cutoff(sw_time, time_cutoff):
"""
Allows for cutting the declustering time window at a specific time, outside
of which an event of any magnitude is no longer identified as a cluster
"""
sw_time = np.array(
[
(time_cutoff / DAYS) if x > (time_cutoff / DAYS) else x
for x in sw_time
]
)
return sw_time
[docs]class BaseDistanceTimeWindow(object):
"""
Defines the space and time windows, within which an event is identified
as a cluster.
"""
[docs] @abc.abstractmethod
def calc(self, magnitude, time_cutoff=None):
"""
Allows to calculate distance and time windows (sw_space, sw_time)
see reference: `Van Stiphout et al (2011)`.
:param magnitude: magnitude
:type magnitude: numpy.ndarray
:param time_cutoff: time window cutoff in days (optional)
:type time_cutoff: int
:returns: distance and time windows
:rtype: numpy.ndarray
"""
return
[docs]@TIME_DISTANCE_WINDOW_FUNCTIONS.add("GardnerKnopoff")
class GardnerKnopoffWindow(BaseDistanceTimeWindow):
"""
Gardner Knopoff method for calculating distance and time windows
"""
[docs] def calc(self, magnitude, time_cutoff=None):
sw_space = np.power(10.0, 0.1238 * magnitude + 0.983)
sw_time = np.power(10.0, 0.032 * magnitude + 2.7389) / DAYS
sw_time[magnitude < 6.5] = (
np.power(10.0, 0.5409 * magnitude[magnitude < 6.5] - 0.547) / DAYS
)
if time_cutoff:
sw_time = time_window_cutoff(sw_time, time_cutoff)
return sw_space, sw_time
[docs]@TIME_DISTANCE_WINDOW_FUNCTIONS.add("Gruenthal")
class GruenthalWindow(BaseDistanceTimeWindow):
"""
Gruenthal method for calculating distance and time windows
"""
[docs] def calc(self, magnitude, time_cutoff=None):
sw_space = np.exp(1.77 + np.sqrt(0.037 + 1.02 * magnitude))
sw_time = np.abs(
(np.exp(-3.95 + np.sqrt(0.62 + 17.32 * magnitude))) / DAYS
)
sw_time[magnitude >= 6.5] = (
np.power(10, 2.8 + 0.024 * magnitude[magnitude >= 6.5]) / DAYS
)
if time_cutoff:
sw_time = time_window_cutoff(sw_time, time_cutoff)
return sw_space, sw_time
[docs]@TIME_DISTANCE_WINDOW_FUNCTIONS.add("UrhammerWindow")
class UhrhammerWindow(BaseDistanceTimeWindow):
"""
Uhrhammer method for calculating distance and time windows
"""
[docs] def calc(self, magnitude, time_cutoff=None):
sw_space = np.exp(-1.024 + 0.804 * magnitude)
sw_time = np.exp(-2.87 + 1.235 * magnitude) / DAYS
if time_cutoff:
sw_time = time_window_cutoff(sw_time, time_cutoff)
return sw_space, sw_time
```