openquake.hazardlib.calc package¶
Hazardlib calculators¶
Disaggregation (disagg)¶
openquake.hazardlib.calc.disagg
contains
disaggregation()
as well as several aggregation functions for
extracting a specific PMF from the result of disaggregation()
.

class
openquake.hazardlib.calc.disagg.
BinData
(mags, dists, lons, lats, trts, pnes)¶ Bases:
tuple

dists
¶ Alias for field number 1

lats
¶ Alias for field number 3

lons
¶ Alias for field number 2

mags
¶ Alias for field number 0

pnes
¶ Alias for field number 5

trts
¶ Alias for field number 4


openquake.hazardlib.calc.disagg.
disaggregation
(sources, site, imt, iml, gsims, truncation_level, n_epsilons, mag_bin_width, dist_bin_width, coord_bin_width, source_site_filter=<openquake.hazardlib.calc.filters.SourceFilter object>)[source]¶ Compute “Disaggregation” matrix representing conditional probability of an intensity mesaure type
imt
exceeding, at least once, an intensity measure leveliml
at a geographical locationsite
, given rupture scenarios classified in terms of: rupture magnitude
 JoynerBoore distance from rupture surface to site
 longitude and latitude of the surface projection of a rupture’s point
closest to
site
 epsilon: number of standard deviations by which an intensity measure level deviates from the median value predicted by a GSIM, given the rupture parameters
 rupture tectonic region type
In other words, the disaggregation matrix allows to compute the probability of each scenario with the specified properties (e.g., magnitude, or the magnitude and distance) to cause one or more exceedences of a given hazard level.
For more detailed information about the disaggregation, see for instance “Disaggregation of Seismic Hazard”, Paolo Bazzurro, C. Allin Cornell, Bulletin of the Seismological Society of America, Vol. 89, pp. 501520, April 1999.
Parameters:  sources – Seismic source model, as for
PSHA
calculator it should be an iterator of seismic sources.  site –
Site
of interest to calculate disaggregation matrix for.  imt – Instance of
intensity measure type
class.  iml – Intensity measure level. A float value in units of
imt
.  gsims – Tectonic region type to GSIM objects mapping.
 truncation_level – Float, number of standard deviations for truncation of the intensity distribution.
 n_epsilons – Integer number of epsilon histogram bins in the result matrix.
 mag_bin_width – Magnitude discretization step, width of one magnitude histogram bin.
 dist_bin_width – Distance histogram discretization step, in km.
 coord_bin_width – Longitude and latitude histograms discretization step, in decimal degrees.
 source_site_filter – Optional sourcesite filter function. See
openquake.hazardlib.calc.filters
.
Returns: A tuple of two items. First is itself a tuple of bin edges information for (in specified order) magnitude, distance, longitude, latitude, epsilon and tectonic region types.
Second item is 6darray representing the full disaggregation matrix. Dimensions are in the same order as bin edges in the first item of the result tuple. The matrix can be used directly by pmfextractor functions.

openquake.hazardlib.calc.disagg.
dist_pmf
(matrix)[source]¶ Fold full disaggregation matrix to distance PMF.
Returns: 1d array, a histogram representing distance PMF.

openquake.hazardlib.calc.disagg.
lon_lat_pmf
(matrix)[source]¶ Fold full disaggregation matrix to longitude / latitude PMF.
Returns: 2d array. First dimension represents longitude histogram bins, second one – latitude histogram bins.

openquake.hazardlib.calc.disagg.
lon_lat_trt_pmf
(matrix)[source]¶ Fold full disaggregation matrix to longitude / latitude / tectonic region type PMF.
Returns: 3d array. Dimension represent longitude, latitude and tectonic region type histogram bins respectively.

openquake.hazardlib.calc.disagg.
mag_dist_eps_pmf
(matrix)[source]¶ Fold full disaggregation matrix to magnitude / distance / epsilon PMF.
Returns: 3d array. First dimension represents magnitude histogram bins, second one – distance histogram bins, third one – epsilon histogram bins.

openquake.hazardlib.calc.disagg.
mag_dist_pmf
(matrix)[source]¶ Fold full disaggregation matrix to magnitude / distance PMF.
Returns: 2d array. First dimension represents magnitude histogram bins, second one – distance histogram bins.

openquake.hazardlib.calc.disagg.
mag_lon_lat_pmf
(matrix)[source]¶ Fold full disaggregation matrix to magnitude / longitude / latitude PMF.
Returns: 3d array. First dimension represents magnitude histogram bins, second one – longitude histogram bins, third one – latitude histogram bins.
Filters (filters)¶
Module filters
contain filter functions for
calculators.
Filters are functions (or other callable objects) that should take generators and return generators. There are two different kinds of filter functions:
 Sourcesite filters. Those functions take a generator of twoitem tuples,
each pair consists of seismic source object (that is, an instance of
a subclass of
BaseSeismicSource
) and a site collection (instance ofSiteCollection
).  Rupturesite filters. Those also take a generator of pairs, but in this
case the first item in the pair is a rupture object (instance of
Rupture
). The second element in generator items is still site collection.
The purpose of both kinds of filters is to limit the amount of calculation
to be done based on some criteria, like the distance between the source
and the site. So common design feature of all the filters is the loop over
pairs of the provided generator, filtering the sites collection, and if
there are no items left in it, skipping the pair and continuing to the next
one. If some sites need to be considered together with that source / rupture,
the pair gets generated out, with a (possibly) limited
site collection.
Consistency of filters’ input and output stream format allows several filters (obviously, of the same kind) to be chained together.
Filter functions should not make assumptions about the ordering of items in the original generator or draw more than one pair at once. Ideally, they should also perform reasonably fast (filtering stage that takes longer than the actual calculation on unfiltered collection only decreases performance).
Module openquake.hazardlib.calc.filters
exports one distancebased
filter function (see filter_sites_by_distance_to_rupture()
) as well as
a “no operation” filter (source_site_noop_filter). There is
a class SourceFilter to determine the sites
affected by a given source: the second one uses an Rtree index and it is
faster if there are a lot of sources, i.e. if the initial time to prepare
the index can be compensed. Finally, there is a function
filter_sites_by_distance_to_rupture based on the JoynerBoore distance.

class
openquake.hazardlib.calc.filters.
SourceFilter
(sitecol, integration_distance, use_rtree=True)[source]¶ Bases:
object
The SourceFilter uses the rtree library if available. The index is generated at instantiation time and kept in memory. The filter should be instantiated only once per calculation, after the site collection is known. It should be used as follows:
ss_filter = SourceFilter(sitecol, integration_distance) for src, sites in ss_filter(sources): do_something(...)
As a side effect, sets the .nsites attribute of the source, i.e. the number of sites within the integration distance. Notice that SourceFilter instances can be pickled, but when unpickled the use_rtree flag is set to false and the index is lost: the reason is that libspatialindex indices cannot be properly pickled (https://github.com/Toblerity/rtree/issues/65).
Parameters:  sitecol –
openquake.hazardlib.site.SiteCollection
instance (or None)  integration_distance – Threshold distance in km, this value gets passed straight to
openquake.hazardlib.source.base.BaseSeismicSource.filter_sites_by_distance_to_source()
which is what is actually used for filtering.  use_rtree – by default True, i.e. try to use the rtree module if available

get_affected_box
(src)[source]¶ Get the enlarged bounding box of a source.
Parameters: src – a source object Returns: a bounding box (min_lon, min_lat, max_lon, max_lat)
 sitecol –

openquake.hazardlib.calc.filters.
context
(*args, **kwds)[source]¶ Used to add the source_id to the error message. To be used as
 with context(src):
 operation_with(src)
Typically the operation is filtering a source, that can fail for tricky geometries.

openquake.hazardlib.calc.filters.
filter_sites_by_distance_to_rupture
(rupture, integration_distance, sites)[source]¶ Filter out sites from the collection that are further from the rupture than some arbitrary threshold.
Parameters:  rupture – Instance of
Rupture
that was generated by :meth: openquake.hazardlib.source.base.BaseSeismicSource.iter_ruptures of an instance of this class.  integration_distance – Threshold distance in km.
 sites – Instance of
openquake.hazardlib.site.SiteCollection
to filter.
Returns: Filtered
SiteCollection
.This function is similar to
openquake.hazardlib.source.base.BaseSeismicSource.filter_sites_by_distance_to_source()
. The same notes about filtering criteria apply. Site should not be filtered out if it is not further than the integration distance from the rupture’s surface projection along the great circle arc (this is known as JoynerBoore distance, :meth:` openquake.hazardlib.geo.surface.base.BaseQuadrilateralSurface.get_joyner_boore_distance`). rupture – Instance of
Ground Motion Fields (gmf)¶
Module gmf
exports
ground_motion_fields()
.

exception
openquake.hazardlib.calc.gmf.
CorrelationButNoInterIntraStdDevs
(corr, gsim)[source]¶ Bases:
exceptions.Exception

class
openquake.hazardlib.calc.gmf.
GmfComputer
(rupture, sites, imts, gsims, truncation_level=None, correlation_model=None, samples=0)[source]¶ Bases:
object
Given an earthquake rupture, the ground motion field computer computes ground shaking over a set of sites, by randomly sampling a ground shaking intensity model.
Parameters: rupture – Rupture to calculate ground motion fields radiated from.  :param
openquake.hazardlib.site.SiteCollection
sites:  Sites of interest to calculate GMFs.
Parameters:  imts – a sorted list of Intensity Measure Type strings
 gsims – a set of GSIM instances
 truncation_level – Float, number of standard deviations for truncation of the intensity
distribution, or
None
.  correlation_model – Instance of correlation model object. See
openquake.hazardlib.correlation
. Can beNone
, in which case noncorrelated ground motion fields are calculated. Correlation model is not used iftruncation_level
is zero.
 :param

openquake.hazardlib.calc.gmf.
ground_motion_fields
(rupture, sites, imts, gsim, truncation_level, realizations, correlation_model=None, seed=None)[source]¶ Given an earthquake rupture, the ground motion field calculator computes ground shaking over a set of sites, by randomly sampling a ground shaking intensity model. A ground motion field represents a possible ‘realization’ of the ground shaking due to an earthquake rupture.
Note
This calculator is using random numbers. In order to reproduce the same results numpy random numbers generator needs to be seeded, see http://docs.scipy.org/doc/numpy/reference/generated/numpy.random.seed.html
Parameters:  rupture (openquake.hazardlib.source.rupture.Rupture) – Rupture to calculate ground motion fields radiated from.
 sites (openquake.hazardlib.site.SiteCollection) – Sites of interest to calculate GMFs.
 imts – List of intensity measure type objects (see
openquake.hazardlib.imt
).  gsim – Groundshaking intensity model, instance of subclass of either
GMPE
orIPE
.  truncation_level – Float, number of standard deviations for truncation of the intensity
distribution, or
None
.  realizations – Integer number of GMF realizations to compute.
 correlation_model – Instance of correlation model object. See
openquake.hazardlib.correlation
. Can beNone
, in which case noncorrelated ground motion fields are calculated. Correlation model is not used iftruncation_level
is zero.  seed (int) – The seed used in the numpy random number generator
Returns: Dictionary mapping intensity measure type objects (same as in parameter
imts
) to 2d numpy arrays of floats, representing different realizations of ground shaking intensity for all sites in the collection. First dimension represents sites and second one is for realizations.
Hazard Curves (hazard_curve)¶
openquake.hazardlib.calc.hazard_curve
implements
calc_hazard_curves()
. Here is an example of a classical PSHA
parallel calculator computing the hazard curves per each realization in less
than 20 lines of code:
import sys
import logging
from openquake.baselib import parallel
from openquake.hazardlib.calc.filters import SourceFilter
from openquake.hazardlib.calc.hazard_curve import calc_hazard_curves
from openquake.commonlib import readinput
def main(job_ini):
logging.basicConfig(level=logging.INFO)
oq = readinput.get_oqparam(job_ini)
sitecol = readinput.get_site_collection(oq)
src_filter = SourceFilter(sitecol, oq.maximum_distance)
csm = readinput.get_composite_source_model(oq).filter(src_filter)
rlzs_assoc = csm.info.get_rlzs_assoc()
for i, sm in enumerate(csm.source_models):
for rlz in rlzs_assoc.rlzs_by_smodel[i]:
gsim_by_trt = rlzs_assoc.gsim_by_trt[rlz.ordinal]
hcurves = calc_hazard_curves(
sm.src_groups, src_filter, oq.imtls,
gsim_by_trt, oq.truncation_level,
parallel.Starmap.apply)
print('rlz=%s, hcurves=%s' % (rlz, hcurves))
if __name__ == '__main__':
main(sys.argv[1]) # path to a job.ini file
NB: the implementation in the engine is smarter and more efficient. Here we start a parallel computation per each realization, the engine manages all the realizations at once.

openquake.hazardlib.calc.hazard_curve.
calc_hazard_curves
(groups, ss_filter, imtls, gsim_by_trt, truncation_level=None, apply=<bound method type.apply of <class 'openquake.baselib.parallel.Sequential'>>)[source]¶ Compute hazard curves on a list of sites, given a set of seismic source groups and a dictionary of ground shaking intensity models (one per tectonic region type).
Probability of ground motion exceedance is computed in different ways depending if the sources are independent or mutually exclusive.
Parameters:  groups – A sequence of groups of seismic sources objects (instances of
of
BaseSeismicSource
).  ss_filter – A source filter over the site collection or the site collection itself
 imtls – Dictionary mapping intensity measure type strings to lists of intensity measure levels.
 gsim_by_trt – Dictionary mapping tectonic region types (members
of
openquake.hazardlib.const.TRT
) toGMPE
orIPE
objects.  truncation_level – Float, number of standard deviations for truncation of the intensity distribution.
 maximum_distance – The integration distance, if any
Returns: An array of size N, where N is the number of sites, which elements are records with fields given by the intensity measure types; the size of each field is given by the number of levels in
imtls
. groups – A sequence of groups of seismic sources objects (instances of
of

openquake.hazardlib.calc.hazard_curve.
get_probability_no_exceedance
(rupture, sctx, rctx, dctx, imtls, gsims, trunclevel, pne_mons)[source]¶ Parameters:  rupture – a Rupture instance
 sctx – the corresponding SiteContext instance
 rctx – the corresponding RuptureContext instance
 dctx – the corresponding DistanceContext instance
 imtls – a dictionarylike object providing the intensity levels
 gsims – the list of GSIMs to use
 trunclevel – the truncation level
 pne_mons – monitors for the probability of no exceedance
Returns: an array of shape (num_sites, num_levels, num_gsims)

openquake.hazardlib.calc.hazard_curve.
pmap_from_grp
(sources, source_site_filter, imtls, gsims, truncation_level=None, bbs=(), monitor=<Monitor dummy>)[source]¶ Compute the hazard curves for a set of sources belonging to the same tectonic region type for all the GSIMs associated to that TRT. The arguments are the same as in
calc_hazard_curves()
, except forgsims
, which is a list of GSIM instances.Returns: a ProbabilityMap instance

openquake.hazardlib.calc.hazard_curve.
poe_map
(src, s_sites, imtls, cmaker, trunclevel, ctx_mon, pne_mons, bbs=(), rup_indep=True, disagg_mon=None)[source]¶ Compute the ProbabilityMap generated by the given source. Also, store some information in the monitors and optionally in the bounding boxes.
Stochastic Event Set (stochastic)¶
openquake.hazardlib.calc.stochastic
contains
stochastic_event_set()
.

openquake.hazardlib.calc.stochastic.
stochastic_event_set
(sources, sites=None, source_site_filter=<openquake.hazardlib.calc.filters.SourceFilter object>)[source]¶ Generates a ‘Stochastic Event Set’ (that is a collection of earthquake ruptures) representing a possible realization of the seismicity as described by a source model.
The calculator loops over sources. For each source, it loops over ruptures. For each rupture, the number of occurrence is randomly sampled by calling
openquake.hazardlib.source.rupture.BaseProbabilisticRupture.sample_number_of_occurrences()
Note
This calculator is using random numbers. In order to reproduce the same results numpy random numbers generator needs to be seeded, see http://docs.scipy.org/doc/numpy/reference/generated/numpy.random.seed.html
Parameters:  sources – An iterator of seismic sources objects (instances of subclasses
of
BaseSeismicSource
).  sites – A list of sites to consider (or None)
 source_site_filter – The source filter to use (only meaningful is sites is not None)
 source_site_filter – The rupture filter to use (only meaningful is sites is not None)
Returns: Generator of
Rupture
objects that are contained in an event set. Some ruptures can be missing from it, others can appear one or more times in a row. sources – An iterator of seismic sources objects (instances of subclasses
of