def amplify_one(self, ampl_code, imt, poes):
"""
:param ampl_code: code for the amplification function
:param imt: an intensity measure type
:param poes: the original PoEs as an array of shape (I, G)
:returns: the amplified PoEs as an array of shape (A, G)
"""
if isinstance(poes, list): # in the tests
poes = numpy.array(poes).reshape(-1, 1)
# Manage the case of a site collection with empty ampcode
if ampl_code == b'' and len(self.ampcodes) == 1:
ampl_code = self.ampcodes[0]
ialphas = self.ialphas[ampl_code, imt]
isigmas = self.isigmas[ampl_code, imt]
A, G = len(self.amplevels), poes.shape[1]
ampl_poes = numpy.zeros((A, G))
# Amplify, for each site i.e. distance
for g in range(G):
# Compute the probability of occurrence of GM within a number of
# intervals
p_occ = -numpy.diff(poes[:, g])
for mid, p, a, s in zip(self.midlevels, p_occ, ialphas, isigmas):
#
# This computes the conditional probabilities of exceeding
# defined values of shaking on soil given a value of shaking
# on rock. 'mid' is the value of ground motion on rock to
# which we associate the probability of occurrence 'p'. 'a'
# is the median amplification factor and 's' is the standard
# deviation of the logarithm of amplification.
#
# In the case of an amplification function without uncertainty
# (i.e. sigma is zero) this will return values corresponding
# to 'p' times 1 (if the value of shaking on rock will be
# larger than the value of shaking on soil) or 0 (if the
# value of shaking on rock will be smaller than the value of
# shaking on soil)
#
logaf = numpy.log(self.amplevels / mid)
ampl_poes[:, g] += (1.0 - norm_cdf(logaf, numpy.log(a), s)) * p
return ampl_poes
def _get_poes_site(mean_std, loglevels, truncation_level, ampfun,
mag, sitecode, rrup, squeeze=False):
"""
NOTE: this works for a single site
:param mean_std:
See :function:`openquake.hazardlib.gsim.base.get_poes`
:param loglevels:
Intensity measure level per intensity measure type. See
:function:`openquake.hazardlib.gsim.base.get_poes`
:param truncation_level:
The level of truncation of the normal distribution of ground-motion
on rock
:param ampl:
Site amplification function instance of
:class:openquake.hazardlib.site_amplification.AmpFunction
:param mag:
The magnitude of the earthquake
:param rrup:
The rrup distances
:param squeeze:
A boolean. Should be True when ...
"""
# Mean and std of ground motion for the IMTs considered in this analysis
# N - Number of sites
# L - Number of intensity measure levels
# G - Number of GMMs
mean, stddev = mean_std # shape (N, M, G)
N, L, G = len(mean), len(loglevels.array), mean.shape[-1]
assert N == 1, N
M = len(loglevels)
L1 = L // M
# This is the array where we store the output results i.e. poes on soil
out_s = numpy.zeros((N, L) if squeeze else (N, L, G))
# `nsamp` is the number of IMLs per IMT used to compute the hazard on rock
# while 'L' is total number of ground-motion values
nsamp = 40
# Compute the probability of exceedance for each in intensity
# measure type IMT
sigma = ampfun.get_max_sigma()
for m, imt in enumerate(loglevels):
# Get the values of ground-motion used to compute the probability of
# exceedance on soil.
soillevels = loglevels[imt]
# Here we set automatically the IMLs that will be used to compute
# the probability of occurrence of GM on rock within discrete
# intervals
ll = numpy.linspace(min(soillevels) - sigma * 4.,
max(soillevels) + sigma * 4.,
num=nsamp)
# Calculate for each ground motion interval the probability
# of occurrence on rock for all the sites
for iml_l, iml_u in zip(ll[:-1], ll[1:]):
# Set the arguments of the truncated normal distribution
# function
if truncation_level == 0:
out_l = iml_l <= mean[:, m]
out_u = iml_u <= mean[:, m]
else:
out_l = (iml_l - mean[:, m]) / stddev[:, m]
out_u = (iml_u - mean[:, m]) / stddev[:, m]
# Probability of occurrence on rock - The shape of this array
# is: number of sites x number of IMLs x GMMs. This corresponds
# to 1 x 1 x number of GMMs
pocc_rock = (_truncnorm_sf(truncation_level, out_l) -
_truncnorm_sf(truncation_level, out_u))
# Skipping cases where the pocc on rock is negligible
if numpy.all(pocc_rock < 1e-10):
continue
# Ground-motion value in the middle of each interval
iml_mid = numpy.log((numpy.exp(iml_l) + numpy.exp(iml_u)) / 2.)
# Get mean and std of the amplification function for this
# magnitude, distance and IML
median_af, std_af = ampfun.get_mean_std(
sitecode, imt, numpy.exp(iml_mid), mag, rrup)
# Computing the probability of exceedance of the levels of
# ground-motion loglevels on soil
logaf = numpy.log(numpy.exp(soillevels) / numpy.exp(iml_mid))
tmp = 1. - norm_cdf(logaf, numpy.log(median_af), std_af)
poex_af = numpy.reshape(numpy.tile(tmp, N), (-1, len(logaf)))
# The probability of occurrence on rock has shape:
# 1 x 1 x number of GMMs
poex = poex_af.T * pocc_rock
# Updating output
out_s[:, m * L1: (m + 1) * L1, :] += poex
return out_s
def amplify_one(self, ampl_code, imt, poes):
"""
:param ampl_code: code for the amplification function
:param imt: an intensity measure type
:param poes: the original PoEs as an array of shape (I, G)
:returns: the amplified PoEs as an array of shape (A, G)
"""
if isinstance(poes, list): # in the tests
poes = numpy.array(poes).reshape(-1, 1)
# Manage the case of a site collection with empty ampcode
if ampl_code == b'' and len(self.ampcodes) == 1:
ampl_code = self.ampcodes[0]
min_gm = numpy.amin(self.imtls[imt])
max_gm = numpy.amax(self.imtls[imt])
min_ratio = numpy.amin(
numpy.array(self.amplevels[1:]) /
numpy.array(self.amplevels[:-1])) * 0.9
min_ratio = min(max(min_ratio, 1.05), 1.1)
allimls = [min_gm]
while allimls[-1] < max_gm:
allimls.append(allimls[-1] * min_ratio)
allimls = numpy.array(allimls)
A, G = len(self.amplevels), poes.shape[1]
ampl_poes = numpy.zeros((A, G))
# Amplify, for each site i.e. distance
for g in range(G):
# Compute the probability of occurrence of GM within a number of
# intervals by interpolating the hazard curve
idx = numpy.nonzero(poes[:, g].flatten() > 1e-100)
simls = allimls[allimls <= numpy.amax(self.imtls[imt][idx])]
ipoes = numpy.interp(numpy.log10(simls),
numpy.log10(self.imtls[imt][idx]),
numpy.log10(poes[:, g].flatten()[idx]))
ipoes = 10.0**ipoes
p_occ = -numpy.diff(ipoes)
# Calculate the amplification factor and sigma for the selected
# IMLs
self.levels = simls
self._set_alpha_sigma(mag=None, dst=None)
ialphas = self.ialphas[ampl_code, imt]
isigmas = self.isigmas[ampl_code, imt]
for mid, p, a, s in zip(self.midlevels, p_occ, ialphas, isigmas):
#
# This computes the conditional probabilities of exceeding
# defined values of shaking on soil given a value of shaking
# on rock. 'mid' is the value of ground motion on rock to
# which we associate the probability of occurrence 'p'. 'a'
# is the median amplification factor and 's' is the standard
# deviation of the logarithm of amplification.
#
# In the case of an amplification function without uncertainty
# (i.e. sigma is zero) this will return values corresponding
# to 'p' times 1 (if the value of shaking on rock will be
# larger than the value of shaking on soil) or 0 (if the
# value of shaking on rock will be smaller than the value of
# shaking on soil)
#
logaf = numpy.log(self.amplevels / mid)
ampl_poes[:, g] += (1.0 - norm_cdf(logaf, numpy.log(a), s)) * p
return ampl_poes