openquake.hmtk.strain package

Subpackages

• openquake.hmtk.strain.regionalisation package
  • Submodules
  • openquake.hmtk.strain.regionalisation.kreemer_regionalisation module
    • KreemerRegionalisation
      • KreemerRegionalisation.define_kreemer_regionalisation()
      • KreemerRegionalisation.get_regionalisation()
  • Module contents

Submodules

openquake.hmtk.strain.geodetic_strain module

openquake.hmtk.strain.geodectic_strain.GeodeticStain is a core class for storage and implementation of a geodetic strain rate model

class openquake.hmtk.strain.geodetic_strain.GeodeticStrain

Bases: object

openquake.hmtk.strain.geodetic_strain.GeodeticStrain describes the geodetic strain model

Parameters:

• data (dict) – Strain data in the form of a dictionary where is vector of attributes is stored under the correponding dictionary key (i.e. - longitude - Longitude of point - latitude - Latitiude of point - exx - xx-component of strain tensor - eyy - yy-component of strain tensor - exy - xy-component of strain tensor

• seismicity_rate (numpy.ndarray) – Seismicity rate at each point associated with the strain model

• target_magnitudes (numpy.ndarray) – Magnitudes for the corresponding activity rates

• data_variables (list) – List of strain data attributes in the current class

get_number_observations()

Returns the number of observations in the data file

get_secondary_strain_data(strain_data=None)

Calculate the following and add to data dictionary: 1) 2nd invarient of strain 2) Dilatation rate 3) e1h and e2h 4) err

Parameters:

strain_data (dict) – Strain data dictionary (as described) - will overwrite current data if input

openquake.hmtk.strain.shift module

openquake.hmtk.strain.shift.Shift implements the Seismic Hazard Inferred from Tectonics (SHIFT) methodology (Bird & Liu, 2007; Bird et al. 2010) for calculating seismic moment rate from Geodetic Strain

class openquake.hmtk.strain.shift.Shift(minimum_magnitude, base_params=None, region_parameter_file=None)

Bases: object

openquake.hmtk.strain.shift.Shift implements the main Seismic Hazard Inferred from Tectonics (SHIFT) methodology for calculating activity rates (Bird & Liu, 2007; Bird et al. 2010)

Parameters:

• strain – Strain model as instance of :class: openquake.hmtk.strain.geodetic_strain.GeodeticStrain

• target_magnitudes (float/list/array) – Magnitude of list of target magnitudes for calculation of the activity rates

• number_magnitudes (int) – Number of magnitudes considered for activity rates

• threshold_moment (np.array) – The scalar moment corresponding to the threshold magnitudes

• regionalisation (list) – List of dictionaries containing the required region-specific attributes required for calculation

• base_rates (np.ndarray) – Minimum (background) rates for each corresponding target magnitude

calculate_activity_rate(strain_data, cumulative=False, in_seconds=False)

Main function to calculate the activity rate (for each of the magnitudes in target_magnitudes) for all of the cells specified in the input strain model file

Parameters:

• strain_data – Strain model as an instance of :class: openquake.hmtk.strain.geodetic_strain.GeodeticStrain

• cumulative (bool) – Set to true if the cumulative rate is required, False for incremental

• in_seconds (bool) – Returns the activity rate in seconds (True) or else as an annual activity rate

continuum_seismicity(threshold_moment, e1h, e2h, err, region_params)

Function to implement the continuum seismicity calculation given vectors of input rates e1h, e2h [np.ndarray] and a dictionary of the corresponding regionalisation params returns a vector of the corresponding seismicity rates Python implementation of the CONTINUUM_SEISMICITY subroutine of SHIFT_GSRM.f90

Parameters:

• threshold_moment (float) – Target moment for calculation of activity rate

• e1h (np.ndarray) – First principal strain rate

• e1h – Second principal strain rate

• err (np.ndarray) – Vertical strain rate

• region_params (dict) – Activity rate parameters specific to the tectonic region under consideration

Returns:

Cumulative seismicity rate greater than or equal to the threshold magnitude

get_rate_osr_convergent_transform(threshold_moment, id0)

Calculates seismicity rate for special case of the ridge condition with convergence and transform

Parameters:

• threshold_moment (float) – Moment required for calculating activity rate

• id0 (np.ndarray) – Logical vector indicating the cells to which this condition applies

Returns:

Activity rates for cells corresponding to the hybrid ocean convergent boundary and oceanic transform condition

get_rate_osr_normal_transform(threshold_moment, id0)

Gets seismicity rate for special case of the ridge condition with spreading and transform component

Parameters:

• threshold_moment (float) – Moment required for calculating activity rate

• id0 (np.ndarray) – Logical vector indicating the cells to which this condition applies

Returns:

Activity rates for cells corresponding to the hybrid ocean spreading ridge and oceanic transform condition

openquake.hmtk.strain.strain_utils module

Module openquake.hmtk.strain.utils holds a set of useful utility functions for the strain rate model calculations

openquake.hmtk.strain.strain_utils.calculate_taper_function(obs_threshold_moment, sel_threshold_moment, corner_moment, beta)

Calculates the tapering function of the tapered Gutenberg & Richter model: as described in Bird & Liu (2007):

taper_function = (M_0(M_T) / M_0(M_T^{CMT}))^-beta x exp((M_0(m_T^CMT) -
    M_0(m_T)) / M_0(m_c))

Parameters:

• obs_threshold_moment (numpy.ndarray) – Moment of the threshold magnitude of the observed earthquake catalogue

• sel_threshold_moment (numpy.ndarray) – Moment of the target magnitude

• corner_momnet (float) – Corner moment of the Tapered Gutenberg-Richter Function

• beta (float) – Beta value (b * ln(10.)) of the Tapered Gutenberg-Richter Function

Returns:

Relative moment rate

openquake.hmtk.strain.strain_utils.moment_function(magnitude)

Get moment (in Nm) from magnitude using Hanks & Kanamori (1979)

Parameters:

magnitude (float (or numpy.ndarray)) – Magnitude of event

Returns:

Seismic Moment in Nm

openquake.hmtk.strain.strain_utils.moment_magnitude_function(moment)

For a given moment, get the moment magnitude using the formula of Hanks & Kanamori (1979)

:param float or numpy.ndarray magnitude

Seismic moment in Nm

openquake.hmtk.strain.strain_utils.tapered_gutenberg_richter_cdf(moment, moment_threshold, beta, corner_moment)

Tapered Gutenberg Richter Cumulative Density Function

Parameters:

• moment (float or numpy.ndarray) – Moment for calculation of rate

• moment_threshold (float or numpy.ndarray) – Threshold Moment of the distribution (moment rate essentially!)

• beta (float) – Beta value (b * ln(10.)) of the Tapered Gutenberg-Richter Function

• corner_momnet (float) – Corner moment of the Tapered Gutenberg-Richter Function

Returns:

Cumulative probability of moment release > moment

openquake.hmtk.strain.strain_utils.tapered_gutenberg_richter_pdf(moment, moment_threshold, beta, corner_moment)

Tapered Gutenberg-Richter Probability Density Function

Parameters:

• moment (float or numpy.ndarray) – Moment for calculation of rate

• moment_threshold (float or numpy.ndarray) – Threshold Moment of the distribution (moment rate essentially!)

• beta (float) – Beta value (b * ln(10.)) of the Tapered Gutenberg-Richter Function

• corner_momnet (float) – Corner moment of the Tapered Gutenberg-Richter Function

Returns:

Absolute probability of moment release > moment

Module contents