gfail.models.godt

This module contains functions that can be used to run Newmark-based mechanistic landslide models.

gfail.models.godt.godt2008(shakefile, config, uncertfile=None, saveinputs=False, displmodel=None, bounds=None, slopediv=100.0, codiv=10.0, numstd=None, trimfile=None)

This function runs the Godt and others (2008) global method for a given ShakeMap. The Factor of Safety is calculated using infinite slope analysis assumuing dry conditions. The method uses threshold newmark displacement and estimates areal coverage by doing the calculations for each slope quantile.

Parameters

• shakefile (str) – Path to shakemap xml file.

• config (ConfigObj) – ConfigObj of config file containing inputs required for running the model

• uncertfile (str) – Path to shakemap uncertainty xml file (optional).

• saveinputs (bool) – Whether or not to return the model input layers, False (default) returns only the model output (one layer).

• displmodel (str) –

  Newmark displacement regression model to use

  • 'J_PGA' (default) – PGA-based model, equation 6 from Jibson (2007).

  • 'J_PGA_M' – PGA and M-based model, equation 7 from Jibson (2007).

  • 'RS_PGA_M' – PGA and M-based model from from Rathje and Saygili (2009).

  • 'RS_PGA_PGV' – PGA and PGV-based model, equation 6 from Saygili and Rathje (2008).

• bounds (dict) – Optional dictionary with keys ‘xmin’, ‘xmax’, ‘ymin’, ‘ymax’ that defines a subset of the shakemap area to compute.

• slopediv (float) – Divide slope by this number to get slope in degrees (Verdin datasets need to be divided by 100).

• codiv (float) – Divide cohesion input layer by this number (For Godt method, need to divide by 10 because that is how it was calibrated).

• numstd (float) – Number of (+/-) standard deviations to use if uncertainty is computed (uncertfile must be supplied).

• trimfile (str) – shapefile of earth’s land masses to trim offshore areas of model

Returns

Dictionary containing output and input layers (if saveinputs=True):

{
    'grid': mapio grid2D object,
    'label': 'label for colorbar and top line of subtitle',
    'type': 'output or input to model',
    'description': {'name': 'short reference of model',
                    'longref': 'full model reference',
                    'units': 'units of output',
                    'shakemap': 'information about shakemap used',
                    'event_id': 'shakemap event id',
                    'parameters': 'dictionary of model parameters
                                   used'

    }
}

Return type

dict

Raises

NameError – when unable to parse the config correctly (probably a formatting issue in the configfile) or when unable to find the shakefile (Shakemap filepath) – these cause program to end.

gfail.models.godt.NMdisp(Ac, PGA, model='J_PGA', M=None, PGV=None)

PGA-based Newmark Displacement model

Parameters

• Ac (array) – NxM array of critical accelerations in units of g.

• PGA (array) – NxM Array of PGA values in units of g.

• model (str) –

  • 'J_PGA' – PGA only model from Jibson (2007), equation 6. Applicable for Magnitude range of dataset (5.3-7.6).

  • 'J_PGA_M' – PGA-and M- based Newmark Displacement model from Jibson(2007), equation 7. Applicable for Magnitude range of dataset (5.3-7.6).

  • 'RS_PGA_M' – PGA and M-based Newmark displacement model from Rathje and Saygili (2009).

  • 'RS_PGA_PGV' – PGA and PGV-based model from Saygili and Rathje (2008) – eq 6.

  • 'BT_PGA_M' – PGA and M-based model from Bray and Travasarou (2007) assuming natural fundamental period of sliding mass Ts = 0 (eq 6).

• M (float) – Magnitude – only needed for models with M in the name.

• PGV (float) – NxM Array of PGV values in units of cm/sec – only needed for models with PGV in the name.

Returns

(Dn, logDnstd, logtype) where:

• Dn: Newmark displacement in cm

• logDnstd: Log of standard deviation of Dn

• logtype: Type of log used in logDnstd (log10 or ln)

Return type

tuple