"""
New Zealand National Seismic Hazard Model 2022 Revision modification of Abrahamson and Gulerce 2020 GMMs.
Backarc term added.
Bradley, B. A., S. Bora, R. L. Lee, E. F. Manea, M. C. Gerstenberger, P.
J. Stafford, G. M. Atkinson, G. Weatherill, J. Hutchinson, C. A. de
la Torre, et al. (2022). Summary of the ground-motion character-
isation model for the 2022 New Zealand National Seismic Hazard
Model, GNS Science Rept. 2022/46, GNS Science, Lower Hutt, New
Zealand, 44 pp.
Bradley, B., S. Bora, R. Lee, E. Manea, M. Gerstenberger, P. Stafford, G.
Atkinson, G. Weatherill, J. Hutchinson, C. de la Torre, et al.
(2023). Summary of the ground-motion characterisation model
for the 2022 New Zealand National Seismic Hazard Model,
Bull. Seismol. Soc. Am.
Lee, R.L., B.A. Bradley, E.F. Manea, J.A. Hutchinson, S.S.
Bora (2022). Evaluation of Empirical Ground-Motion Models for the 2022 New
Zealand National Seismic Hazard Model Revision, Bull. Seismol. Soc. Am.
Module exports :class:`NZNSHM2022_AbrahamsonGulerce2020SInter`
:class:`class NZNSHM2022_AbrahamsonGulerce2020SSlab`
"""
import numpy as np
from scipy.interpolate import interp1d
from openquake.hazardlib import const
from openquake.hazardlib.imt import PGA
from openquake.hazardlib.gsim.base import add_alias
from openquake.hazardlib.gsim.abrahamson_gulerce_2020 import (
AbrahamsonGulerce2020SInter,
get_acceleration_on_reference_rock,
get_epistemic_adjustment,
get_mean_acceleration,
get_tau_phi,
SUPPORTED_REGIONS,
)
from openquake.hazardlib.gsim.nz22.const import periods, theta7s, theta8s
[docs]def get_backarc_term(trt, imt, ctx):
"""
The backarc correction factors to be applied with the ground motion
prediction. In the NZ context, it is applied to only subduction
intraslab events. It is essentially the correction factor taken
from BC Hydro 2016. Abrahamson et al. (2016) Earthquake Spectra.
The correction is applied only for backarc sites as function of
distance.
"""
period = imt.period
w_epi_factor = 1.008
theta7_itp = interp1d(np.log(periods[1:]), theta7s[1:])
theta8_itp = interp1d(np.log(periods[1:]), theta8s[1:])
# Note that there is no correction for PGV. Hence, I make theta7
# and theta8 as 0 for periods < 0.
if period < 0:
theta7 = 0.0
theta8 = 0.0
elif period >= 0 and period < 0.02:
theta7 = 1.0988
theta8 = -1.42
else:
theta7 = theta7_itp(np.log(period))
theta8 = theta8_itp(np.log(period))
dists = ctx.rrup
if trt == const.TRT.SUBDUCTION_INTRASLAB:
min_dist = 85.0
backarc = np.bool_(ctx.backarc)
f_faba = np.zeros_like(dists)
fixed_dists = dists[backarc]
fixed_dists[fixed_dists < min_dist] = min_dist
f_faba[backarc] = theta7 + theta8 * np.log(fixed_dists / 40.0)
return f_faba * w_epi_factor
else:
f_faba = np.zeros_like(dists)
return f_faba
[docs]def get_acceleration_on_reference_rock_ba(
C, trt, region, ctx, apply_adjustment
):
return get_acceleration_on_reference_rock(
C, trt, region, ctx, apply_adjustment
) + get_backarc_term(trt, PGA(), ctx)
[docs]def get_mean_acceleration_ba(
C, trt, region, ctx, pga1000, imt, apply_adjustment
):
return get_mean_acceleration(
C, trt, region, ctx, pga1000, imt, apply_adjustment,
) + get_backarc_term(trt, imt, ctx)
[docs]class NZNSHM2022_AbrahamsonGulerce2020SInter(AbrahamsonGulerce2020SInter):
def __init__(
self,
region="GLO",
ergodic=True,
apply_usa_adjustment=False,
sigma_mu_epsilon=0.0,
):
super().__init__(
region=region,
ergodic=ergodic,
apply_usa_adjustment=apply_usa_adjustment,
sigma_mu_epsilon=sigma_mu_epsilon)
[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.
"""
trt = self.DEFINED_FOR_TECTONIC_REGION_TYPE
C_PGA = self.COEFFS[PGA()]
pga1000 = get_acceleration_on_reference_rock_ba(
C_PGA, trt, self.region, ctx, self.apply_usa_adjustment
)
pga1000 = np.exp(pga1000)
for m, imt in enumerate(imts):
C = self.COEFFS[imt]
mean[m] = get_mean_acceleration_ba(
C,
trt,
self.region,
ctx,
pga1000,
imt,
self.apply_usa_adjustment
)
if self.sigma_mu_epsilon:
# Apply an epistmic adjustment factor
mean[m] += self.sigma_mu_epsilon * get_epistemic_adjustment(
C, ctx.rrup
)
# Get the standard deviations
tau_m, phi_m = get_tau_phi(
C,
C_PGA,
self.region,
imt.period,
ctx.rrup,
ctx.vs30,
pga1000,
self.ergodic,
)
tau[m] = tau_m
phi[m] = phi_m
sig += np.sqrt(tau**2.0 + phi**2.0)
[docs]class NZNSHM2022_AbrahamsonGulerce2020SSlab(
NZNSHM2022_AbrahamsonGulerce2020SInter
):
REQUIRES_RUPTURE_PARAMETERS = {"mag", "ztor"}
REQUIRES_SITES_PARAMETERS = {"vs30", "backarc"}
#: Supported tectonic region type is subduction inslab
DEFINED_FOR_TECTONIC_REGION_TYPE = const.TRT.SUBDUCTION_INTRASLAB
REGION_ALIASES = {
"GLO": "",
"USA-AK": "Alaska",
"CAS": "Cascadia",
"CAM": "CentralAmericaMexico",
"JPN": "Japan",
"NZL": "NewZealand",
"SAM": "SouthAmerica",
"TWN": "Taiwan",
}
for region in SUPPORTED_REGIONS[1:]:
add_alias(
"NZNSHM2022_AbrahamsonGulerce2020SInter" + REGION_ALIASES[region],
NZNSHM2022_AbrahamsonGulerce2020SInter,
region=region,
)
add_alias(
"NZNSHM2022_AbrahamsonGulerce2020SSlab" + REGION_ALIASES[region],
NZNSHM2022_AbrahamsonGulerce2020SSlab,
region=region,
)
