Comment 1 for bug 1046720

The extraction of hazard curves from ground motion fields (gmfs) should be an option that a user can select in the [output] section of the job configuration file. That is a user should be able to specify (as in the classical calculation mode):

intensity_measure_types_and_levels = {"PGA": [0.005, 0.007, 0.0098, 0.0137, 0.0192, 0.0269, 0.0376, 0.0527, 0.0738, 0.103, 0.145, 0.203, 0.284, 0.397, 0.556, 0.778, 1.09, 1.52, 2.13], "SA(0.025)": [0.005, 0.007, 0.0098, 0.0137, 0.0192, 0.0269, 0.0376, 0.0527, 0.0738, 0.103, 0.145, 0.203, 0.284, 0.397, 0.556, 0.778, 1.09, 1.52, 2.13]}

if intensity_measure_types_and_levels is empty than this means that hazard curves are not extracted. There must be consistency between the intensity measure types defined in intensity_measure_types_and_levels and in intensity_measure_types (in the [calculation] section). That is if gmfs are computed only for PGA, a user cannot extract the hazard curves for SA.

By default hazard curves should be computed for all the logic tree paths and also from the complete logic tree gmf set (that is the set of gmfs obtained by joining the gmfs from all logic tree paths)

The extraction of hazard curves from a set of gmf is descrived below.

Given a site, an intensity measure type (PGA or SA for instance), a list of intensity measure levels ([IML_1, IML_2, ..., IML_N]) extract all the computed ground motion values ([GMV_1, GMV_2, ..., GMV_M]) and the corresponding duration T (if the ground motion fields correspond to a logic tree path, the duration is 'ses_per_logic_tree_path * investigation_time', if the gmf set corresponds to the complete logic tree, the duration is 'ses_per_logic_tree_path * investigation_time * number_of_logic_tree_samples' if Monte Carlo sampling of logic tree is chosen or 'ses_per_logic_tree_path * investigation_time * number_of_logic_tree_paths' if Enumeration is chosen)

For each IML in [IML_1, IML_2, ..., IML_N] compute the number of values (N) in [GMV_1, GMV_2, ..., GMV_M] that are greater or equal than IML. The probability of exceeding IML can be then computed as:
P(>=IML) = 1 - exp(- (investigation_time / duration) * N )