Source code for openquake.hazardlib.gsim.abrahamson_silva_1997

# -*- coding: utf-8 -*-
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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"""
Module exports :class:`AbrahamsonSilva1997`.
"""
import numpy as np

from openquake.hazardlib.gsim.base import GMPE, CoeffsTable
from openquake.hazardlib import const
from openquake.hazardlib.imt import PGA, SA


def _compute_mean_on_rock(C, mag, rrup, F, HW):
    """
    Compute mean value on rock (that is eq.1, page 105 with S = 0)
    """
    f1 = _compute_f1(C, mag, rrup)
    f3 = _compute_f3(C, mag)
    f4 = _compute_f4(C, mag, rrup)
    return f1 + F * f3 + HW * f4


def _get_fault_type_hanging_wall(rake):
    """
    Return fault type (F) and hanging wall (HW) flags depending on rake
    angle.

    The method assumes 'reverse' (F = 1) if 45 <= rake <= 135, 'other'
    (F = 0) if otherwise. Hanging-wall flag is set to 1 if 'reverse',
    and 0 if 'other'.
    """
    F, HW = np.zeros_like(rake), np.zeros_like(rake)
    within = (45 <= rake) & (rake <= 135)
    F[within] = 1.
    HW[within] = 1.
    return F, HW


def _get_site_class(vs30):
    """
    Return site class flag (0 if vs30 > 600, that is rock, or 1 if vs30 <
    600, that is deep soil)
    """
    S = np.zeros_like(vs30)
    S[vs30 < 600] = 1
    return S


def _compute_f1(C, mag, rrup):
    """
    Compute f1 term (eq.4, page 105)
    """
    r = np.sqrt(rrup ** 2 + C['c4'] ** 2)

    f1 = (C['a1'] +
          C['a12'] * (8.5 - mag) ** C['n'] +
          (C['a3'] + C['a13'] * (mag - C['c1'])) * np.log(r))

    f1[mag <= C['c1']] += C['a2'] * (mag[mag <= C['c1']] - C['c1'])
    f1[mag > C['c1']] += C['a4'] * (mag[mag > C['c1']] - C['c1'])

    return f1


def _compute_f3(C, mag):
    """
    Compute f3 term (eq.6, page 106)

    NOTE: In the original manuscript, for the case 5.8 < mag < c1,
    the term in the numerator '(mag - 5.8)' is missing, while is
    present in the software used for creating the verification tables
    """
    f3 = C['a5'] + (C['a6'] - C['a5']) * (mag - 5.8) / (C['c1'] - 5.8)
    f3[mag <= 5.8] = C['a5']
    f3[mag >= C['c1']] = C['a6']
    return f3


def _compute_f4(C, mag, rrup):
    """
    Compute f4 term (eq. 7, 8, and 9, page 106)
    """
    fhw_m = 0
    fhw_r = np.zeros_like(rrup)

    fhw_m = np.clip(mag - 5.5, 0., 1.)

    idx = (rrup > 4) & (rrup <= 8)
    fhw_r[idx] = C['a9'] * (rrup[idx] - 4.) / 4.

    idx = (rrup > 8) & (rrup <= 18)
    fhw_r[idx] = C['a9']

    idx = (rrup > 18) & (rrup <= 24)
    fhw_r[idx] = C['a9'] * (1 - (rrup[idx] - 18.) / 7.)

    return fhw_m * fhw_r


def _compute_f5(C, pga_rock):
    """
    Compute f5 term (non-linear soil response)
    """
    return C['a10'] + C['a11'] * np.log(pga_rock + C['c5'])


[docs]class AbrahamsonSilva1997(GMPE): """ Implements GMPE developed by N. A. Abrahamson and W. J. Silva and published as "Empirical Response Spectral Attenuation Relations for Shallow Crustal Earthquakes", Seismological Research Letters, v.68, no. 1, p. 94-127, 1997. The GMPE distinguishes between rock (vs30 >= 600) and deep soil (vs30 < 600). The rake angle is also taken into account to distinguish between 'reverse' (45 <= rake < 135) and 'other'. If an earthquake rupture is classified as 'reverse', then the hanging-wall term is included in the mean calculation. """ #: Supported tectonic region type is 'active shallow crust' (see #: Introduction, page 94) DEFINED_FOR_TECTONIC_REGION_TYPE = const.TRT.ACTIVE_SHALLOW_CRUST #: Supported intensity measure types are PGA and SA. PGA is assumed to #: have same coefficients as SA(0.01) DEFINED_FOR_INTENSITY_MEASURE_TYPES = {PGA, SA} #: Supported intensity measure component is the geometric mean of two #: horizontal components (see paragraph 'Regression Model', page 105) DEFINED_FOR_INTENSITY_MEASURE_COMPONENT = const.IMC.AVERAGE_HORIZONTAL #: Supported standard deviation type is Total (see equations 13 pp. 106 #: and table 4, page 109). DEFINED_FOR_STANDARD_DEVIATION_TYPES = {const.StdDev.TOTAL} #: The only site parameter is vs30 used to distinguish between rock #: (vs30 > 600 m/s) and deep soil (see table 2, page 95) REQUIRES_SITES_PARAMETERS = {'vs30'} #: Required rupture parameters are magnitude, and rake (eq. 3, page 105). #: Rake is used to distinguish between 'reverse' (45 <= rake <= 135) and #: 'other' (i.e. strike-slip and normal). If an earthquake is classified #: as 'reverse' than the hanging-wall term is taken into account. REQUIRES_RUPTURE_PARAMETERS = {'mag', 'rake'} #: Required distance measure is RRup (eq. 3, page 105). REQUIRES_DISTANCES = {'rrup'}
[docs] def compute(self, ctx: np.recarray, imts, mean, sig, tau, phi): """ See :meth:`superclass method <.base.GroundShakingIntensityModel.compute>` for spec of input and result values. """ F, HW = _get_fault_type_hanging_wall(ctx.rake) S = _get_site_class(ctx.vs30) # compute pga on rock (used then to compute site amplification factor) C = self.COEFFS[PGA()] pga_rock = np.exp(_compute_mean_on_rock(C, ctx.mag, ctx.rrup, F, HW)) for m, imt in enumerate(imts): # compute mean for the given imt (do not repeat the calculation if # imt is PGA, just add the site amplification term) if imt == PGA(): mean[m] = np.log(pga_rock) + S * _compute_f5(C, pga_rock) else: C = self.COEFFS[imt] mean[m] = (_compute_mean_on_rock(C, ctx.mag, ctx.rrup, F, HW) + S * _compute_f5(C, pga_rock)) C_STD = self.COEFFS_STD[imt] # standard deviation as defined in eq.13 page 106. sigma = C_STD['b5'] - C_STD['b6'] * (ctx.mag - 5) sigma[ctx.mag <= 5.] = C_STD['b5'] sigma[ctx.mag >= 7.] = C_STD['b5'] - 2 * C_STD['b6'] sig[m] += sigma
#: Coefficient table (table 3, page 108) COEFFS = CoeffsTable(sa_damping=5, table="""\ imt c4 a1 a2 a3 a4 a5 a6 a9 a10 a11 a12 a13 c1 c5 n pga 5.60 1.640 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.417 -0.230 0.0000 0.17 6.4 0.03 2 0.01 5.60 1.640 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.417 -0.230 0.0000 0.17 6.4 0.03 2 0.02 5.60 1.640 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.417 -0.230 0.0000 0.17 6.4 0.03 2 0.03 5.60 1.690 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.470 -0.230 0.0143 0.17 6.4 0.03 2 0.04 5.60 1.780 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.555 -0.251 0.0245 0.17 6.4 0.03 2 0.05 5.60 1.870 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.620 -0.267 0.0280 0.17 6.4 0.03 2 0.06 5.60 1.940 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.665 -0.280 0.0300 0.17 6.4 0.03 2 0.075 5.58 2.037 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.628 -0.280 0.0300 0.17 6.4 0.03 2 0.09 5.54 2.100 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.609 -0.280 0.0300 0.17 6.4 0.03 2 0.10 5.50 2.160 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.598 -0.280 0.0280 0.17 6.4 0.03 2 0.12 5.39 2.272 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.591 -0.280 0.0180 0.17 6.4 0.03 2 0.15 5.27 2.407 0.512 -1.1450 -0.144 0.610 0.260 0.370 -0.577 -0.280 0.0050 0.17 6.4 0.03 2 0.17 5.19 2.430 0.512 -1.1350 -0.144 0.610 0.260 0.370 -0.522 -0.265 -0.0040 0.17 6.4 0.03 2 0.20 5.10 2.406 0.512 -1.1150 -0.144 0.610 0.260 0.370 -0.445 -0.245 -0.0138 0.17 6.4 0.03 2 0.24 4.97 2.293 0.512 -1.0790 -0.144 0.610 0.232 0.370 -0.350 -0.223 -0.0238 0.17 6.4 0.03 2 0.30 4.80 2.114 0.512 -1.0350 -0.144 0.610 0.198 0.370 -0.219 -0.195 -0.0360 0.17 6.4 0.03 2 0.36 4.62 1.955 0.512 -1.0052 -0.144 0.610 0.170 0.370 -0.123 -0.173 -0.0460 0.17 6.4 0.03 2 0.40 4.52 1.860 0.512 -0.9880 -0.144 0.610 0.154 0.370 -0.065 -0.160 -0.0518 0.17 6.4 0.03 2 0.46 4.38 1.717 0.512 -0.9652 -0.144 0.592 0.132 0.370 0.020 -0.136 -0.0594 0.17 6.4 0.03 2 0.50 4.30 1.615 0.512 -0.9515 -0.144 0.581 0.119 0.370 0.085 -0.121 -0.0635 0.17 6.4 0.03 2 0.60 4.12 1.428 0.512 -0.9218 -0.144 0.557 0.091 0.370 0.194 -0.089 -0.0740 0.17 6.4 0.03 2 0.75 3.90 1.160 0.512 -0.8852 -0.144 0.528 0.057 0.331 0.320 -0.050 -0.0862 0.17 6.4 0.03 2 0.85 3.81 1.020 0.512 -0.8648 -0.144 0.512 0.038 0.309 0.370 -0.028 -0.0927 0.17 6.4 0.03 2 1.00 3.70 0.828 0.512 -0.8383 -0.144 0.490 0.013 0.281 0.423 0.000 -0.1020 0.17 6.4 0.03 2 1.50 3.55 0.260 0.512 -0.7721 -0.144 0.438 -0.049 0.210 0.600 0.040 -0.1200 0.17 6.4 0.03 2 2.00 3.50 -0.150 0.512 -0.7250 -0.144 0.400 -0.094 0.160 0.610 0.040 -0.1400 0.17 6.4 0.03 2 3.00 3.50 -0.690 0.512 -0.7250 -0.144 0.400 -0.156 0.089 0.630 0.040 -0.1726 0.17 6.4 0.03 2 4.00 3.50 -1.130 0.512 -0.7250 -0.144 0.400 -0.200 0.039 0.640 0.040 -0.1956 0.17 6.4 0.03 2 5.00 3.50 -1.460 0.512 -0.7250 -0.144 0.400 -0.200 0.000 0.664 0.040 -0.2150 0.17 6.4 0.03 2 """) #: Coefficient table for standard deviation calculation (table 4, page 109) COEFFS_STD = CoeffsTable(sa_damping=5, table="""\ imt b5 b6 pga 0.70 0.135 0.01 0.70 0.135 0.02 0.70 0.135 0.03 0.70 0.135 0.04 0.71 0.135 0.05 0.71 0.135 0.06 0.72 0.135 0.075 0.73 0.135 0.09 0.74 0.135 0.10 0.74 0.135 0.12 0.75 0.135 0.15 0.75 0.135 0.17 0.76 0.135 0.20 0.77 0.135 0.24 0.77 0.135 0.30 0.78 0.135 0.36 0.79 0.135 0.40 0.79 0.135 0.46 0.80 0.132 0.50 0.80 0.130 0.60 0.81 0.127 0.75 0.81 0.123 0.85 0.82 0.121 1.00 0.83 0.118 1.50 0.84 0.110 2.00 0.85 0.105 3.00 0.87 0.097 4.00 0.88 0.092 5.00 0.89 0.087 """)