openquake.hazardlib.calc package¶

Hazardlib calculators¶

Disaggregation (openquake.hazardlib.calc.disagg module)¶

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 level iml at a geographical location site, given rupture scenarios classified in terms of:

rupture magnitude
Joyner-Boore 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. 501-520, 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 source-site 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 6d-array 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 pmf-extractor 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.

openquake.hazardlib.calc.disagg.mag_pmf(matrix)[source]¶

Fold full disaggregation matrix to magnitude PMF.

Returns:	1d array, a histogram representing magnitude PMF.

openquake.hazardlib.calc.disagg.trt_pmf(matrix)[source]¶

Fold full disaggregation matrix to tectonic region type PMF.

Returns:	1d array, a histogram representing tectonic region type PMF.

Filters (openquake.hazardlib.calc.filters module)¶

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:

Source-site filters. Those functions take a generator of two-item tuples, each pair consists of seismic source object (that is, an instance of a subclass of BaseSeismicSource) and a site collection (instance of SiteCollection).
Rupture-site 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 distance-based 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 R-tree 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 Joyner-Boore 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 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

affected(source)[source]¶: Returns the sites within the integration distance from the source, or None.

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)

get_rectangle(src)[source]¶

Parameters:	src – a source object
Returns:	((min_lon, min_lat), width, height), useful for plotting

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 Joyner-Boore distance, :meth:` openquake.hazardlib.geo.surface.base.BaseQuadrilateralSurface.get_joyner_boore_distance`).

Ground Motion Fields (openquake.hazardlib.calc.gmf module)¶

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
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 be None, in which case non-correlated ground motion fields are calculated. Correlation model is not used if truncation_level is zero.

compute(gsim, num_events, seed=None)[source]¶

Parameters:	gsim – a GSIM instance num_events – the number of seismic events seed – a random seed or None
Returns:	a 32 bit array of shape (num_imts, num_sites, num_events)

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 – Ground-shaking intensity model, instance of subclass of either GMPE or IPE.
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 be None, in which case non-correlated ground motion fields are calculated. Correlation model is not used if truncation_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 (openquake.hazardlib.calc.hazard_curve module)¶

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()
    sources = csm.get_sources()
    for rlzno, gsim_by_trt in enumerate(rlzs_assoc.gsim_by_trt):
        hcurves = calc_hazard_curves(sources, src_filter, oq.imtls,
                                     gsim_by_trt, oq.truncation_level,
                                     parallel.apply)
        print('rlzno=%d, hcurves=%r' % (rlzno, 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(sources, source_site_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 sources and a set of ground shaking intensity models (one per tectonic region type considered in the seismic sources).

Probability of ground motion exceedance is computed using the following formula

P(X≥x|T) = 1 - ∏ ∏ Prup_ij(X<x|T)

where P(X≥x|T) is the probability that the ground motion parameter X is exceeding level x one or more times in a time span T, and Prup_ij(X<x|T) is the probability that the j-th rupture of the i-th source is not producing any ground motion exceedance in time span T. The first product ∏ is done over sources, while the second one is done over ruptures in a source.

The above formula computes the probability of having at least one ground motion exceedance in a time span as 1 minus the probability that none of the ruptures in none of the sources is causing a ground motion exceedance in the same time span. The basic assumption is that seismic sources are independent, and ruptures in a seismic source are also independent.

Parameters:

sources – A sequence of seismic sources objects (instances of subclasses of BaseSeismicSource).
source_site_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) to GMPE or IPE objects.
truncation_level – Float, number of standard deviations for truncation of the intensity distribution.
apply – Application function, for instance parallel.apply; by default use openquake.baselib.parallel.Sequential.apply.

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.

openquake.hazardlib.calc.hazard_curve.calc_hazard_curves_ext(groups, source_site_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:

group – A sequence of groups of seismic sources objects (instances of of BaseSeismicSource).
source_site_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) to GMPE or IPE objects.
truncation_level – Float, number of standard deviations for truncation of the intensity distribution.
source_site_filter – Optional source-site filter function. See openquake.hazardlib.calc.filters.
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.

openquake.hazardlib.calc.hazard_curve.get_probability_no_exceedance(rupture, sctx, rctx, dctx, imtls, gsims, trunclevel)[source]¶

Parameters:	rupture – a Rupture instance sctx – the corresponding SiteContext instance rctx – the corresponding RuptureContext instance dctx – the corresponding DistanceContext instance imtls – a dictionary-like object providing the intensity levels gsims – the list of GSIMs to use trunclevel – the truncation level
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 for gsims, which is a list of GSIM instances.

Returns:	a ProbabilityMap instance

openquake.hazardlib.calc.hazard_curve.poe_map(src, s_sites, imtls, cmaker, trunclevel, bbs, rup_indep, ctx_mon, pne_mon, disagg_mon)[source]¶: Compute the ProbabilityMap generated by the given source. Also, store some information in the monitors and optionally in the bounding boxes.

openquake.hazardlib.calc.hazard_curve.rupture_weight_pairs(src)[source]¶: Generator yielding (rupture, weight) for each rupture in the source

openquake.hazardlib.calc.hazard_curve.zero_curves(num_sites, imtls)[source]¶

Parameters:	num_sites – the number of sites imtls – the intensity measure levels dictionary
Returns:	an array of zero curves with length num_sites

Stochastic Event Set (openquake.hazardlib.calc.stochastic module)¶

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.

openquake.hazardlib.calc package¶

Hazardlib calculators¶

Disaggregation (openquake.hazardlib.calc.disagg module)¶

Filters (openquake.hazardlib.calc.filters module)¶

Ground Motion Fields (openquake.hazardlib.calc.gmf module)¶

Hazard Curves (openquake.hazardlib.calc.hazard_curve module)¶

Stochastic Event Set (openquake.hazardlib.calc.stochastic module)¶

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