Update src/seismic_hazard_forecasting.py

src/seismic_hazard_forecasting.py

@@ -1,10 +1,189 @@
 # -*- coding: utf-8 -*-
+import numpy as np
+from scipy.stats import t, norm
+from scipy.optimize import root_scalar
+from timeit import default_timer as timer
+
+from openquake.hazardlib.geo import Point #This class represents a geographical point in terms of longitude, latitude, and depth (with respect to the Earth surface).
+from openquake.hazardlib.geo.surface.planar import PlanarSurface
+from openquake.hazardlib.source.characteristic import CharacteristicFaultSource
+from openquake.hazardlib.mfd import ArbitraryMFD
+from openquake.hazardlib.tom import PoissonTOM
+from openquake.hazardlib.scalerel import WC1994 #Wells and Coppersmith magnitude – rupture area relationships
+from openquake.hazardlib.site import Site, SiteCollection
+from openquake.hazardlib.contexts import ContextMaker
+from openquake.hazardlib.valid import gsim
+from openquake.hazardlib.imt import PGA
+
+
 def my_trivial_task(x):
     """
     A function that does a trivial task
     """
     return x * x
 
+def compute_IMT_exceedance(rx_lat, rx_lon, r, fr, p, lambdas, D, percentages_D, magnitudes, magnitude_pdf, magnitude_cdf, model, imt='PGA', IMT_min=0.01, IMT_max=2.0, rx_label=None, rtol=0.1, use_cython=False, **kwargs):
+    
+    n_events = len(r)
+        
+    try:
+        gmpes = [gsim(model)]
+    except:
+        msg = f"{model} was not found in the openquake gsim directory" 
+        logger.error(msg)
+        raise Exception(msg) 
+    
+    if model == 'Lasocki2013': #this model requires the number of earthquake records
+    
+        if imt=='PGA': #extract number of records for PGA
+            num_ground_motion_records = gmpes[0].COEFFS.non_sa_coeffs[PGA()]['N']
+        else: #extract number of records for SA()
+            freq = float(imt[imt.find('(')+1:imt.find(')')]) # get the desired frequency of SA
+            first_index = np.where(gmpes[0].COEFFS.get_coeffs('N')[0]==freq)[0][0]
+            num_ground_motion_records = gmpes[0].COEFFS.get_coeffs('N')[1][first_index][0]
+    else:
+        num_ground_motion_records = 0
+                               
+    #placeholder values that do not have any effect
+    Mag = 5.0 #placeholder mag, must be valid for that context; will be overwritten in loop
+    rupture_aratio = 1.5
+    Strike = 0
+    Dip = 90
+    Rake = 0
+    
+    Hypocenter = Point(rx_lon, rx_lat, 0.0) #does not matter in our case; just set eq location to be same as receiver
+    #according to the magnitude and MSR calculate planar surface
+    planar_surface = PlanarSurface.from_hypocenter(
+            hypoc=Hypocenter,
+            msr=WC1994(),
+            mag=Mag,
+            aratio=rupture_aratio,
+            strike=Strike,
+            dip=Dip,
+            rake=Rake,
+            )
+
+    # site for which we compute (receiver location)    
+    site_collection = SiteCollection([Site(location=Point(rx_lon, rx_lat, 0))])
+
+    imtls = {s: [0] for s in [imt]} #required for context maker, M = 2 IMTs
+
+    context_maker = ContextMaker('Induced', gmpes, {'imtls': imtls, 'mags': [Mag]}) #necessary contexts builder
+
+    src = CharacteristicFaultSource(source_id = 1,
+                                    name = 'rup',
+                                    tectonic_region_type = 'Induced',
+                                    mfd = ArbitraryMFD([Mag], [0.01]), #this does not have any effect
+                                    temporal_occurrence_model = PoissonTOM(50.), #this is also not really used
+                                    surface = planar_surface,
+                                    rake = Rake)
+
+    ctx = context_maker.from_srcs([src], site_collection)[0] #returns one context from the source for one rupture   
+
+    if use_cython:
+
+        from cython_exceedance import exceedance_core
+    
+        def exceedance_root_function(a):
+            return exceedance_core(a, r, fr, lambdas, D, percentages_D, magnitudes,
+                                   magnitude_pdf, magnitude_cdf, context_maker, ctx,
+                                   model, num_ground_motion_records) - p
+
+    else:
+    
+        def exceedance_root_function(a):
+            exceedance_prob_sum = 0
+            log_a = np.log(a) # Precompute log(a)
+        
+            for j in range(len(lambdas)): #loop through all lambdas
+                lambda_j = lambdas[j]
+                D_j_val = percentages_D[j] * D # Use a different name to avoid shadowing D
+                lambda_D_j = lambda_j * D_j_val
+                denom_j = (1 - np.exp(-lambda_D_j))
+                if denom_j == 0: # Avoid division by zero if lambda_D_j is very small or zero
+                   continue
+        
+                for i in range(n_events): #loop through all events
+                    ri = r[i] # Epicentral distance
+                    fr_i = fr[i] # Location probability f(r)
+                    ctx.repi = ri
+        
+                    # Precompute terms only dependent on lambda_j, D_j, m
+                    lambda_D_j_f_m = lambda_D_j * magnitude_pdf
+                    exp_term_m = np.exp(-lambda_D_j * (1 - magnitude_cdf))
+                    f_conditional_base_m = (lambda_D_j_f_m * exp_term_m) / denom_j
+        
+                    for k in range(len(magnitudes)):  #loop through all values of magnitude pdf and cdf
+                        m = magnitudes[k]
+                        ctx.mag = m # update context magnitude 
+        
+                        # Calculate f_conditional (simpler now)
+                        f_conditional = f_conditional_base_m[k]
+        
+                        mean, sig, _, _ = context_maker.get_mean_stds(ctx)
+                        log_gm_predicted = mean[0][0][0]
+                        variance_term = sig[0][0][0]
+                        residual = log_a - log_gm_predicted # Use precomputed log_a
+        
+                        if residual <= 0:
+                             exceedance_probability = 1.0
+                        else:
+                             # Avoid division by zero or very small numbers if variance_term is ~0
+                             if variance_term < 1e-15: # Adjust threshold as needed
+                                 exceedance_probability = 0.0
+                             else:
+                                t_value = residual / variance_term
+                                
+                                if model == 'Lasocki2013':
+                                    exceedance_probability = t.sf(t_value, num_ground_motion_records - 3) # student t distribution, degrees of freedom: n-3; sf = 1 - cdf
+                                else:
+                                    exceedance_probability = norm.sf(t_value) # equivalent to 1.0 - norm.cdf(t_value)
+        
+                        location_exceedance_prob = exceedance_probability * f_conditional * fr_i
+                        exceedance_prob_sum += location_exceedance_prob
+        
+            return exceedance_prob_sum - p
+    
+      
+    
+    # Check function values at different test points
+    IMT_mid = (IMT_max-IMT_min)/2
+    lower_bound_value = exceedance_root_function(IMT_min)
+    mid_point_value = exceedance_root_function(IMT_mid)
+    upper_bound_value = exceedance_root_function(IMT_max)
+    
+    logger.info(f"Receiver: {str(rx_label)}")
+    logger.info(f"Function value at {imt} = {str(IMT_min)} : {lower_bound_value}")
+    logger.info(f"Function value at {imt} = {str(IMT_mid)} : {mid_point_value}")
+    logger.info(f"Function value at {imt} = {str(IMT_max)} : {upper_bound_value}")
+    
+    if np.sign(lower_bound_value) == np.sign(upper_bound_value):
+        msg = "Function values at the interval endpoints must differ in sign for fsolve to work. Expand the interval or use a different model."
+        logger.error(msg)
+        gm_est = np.nan
+        return gm_est
+        # raise ValueError(msg)
+    
+    # Find root of function
+    start = timer()       
+        
+    try: 
+        method='brenth'
+        logger.debug("Now trying Scipy " + method)
+        output = root_scalar(exceedance_root_function, bracket=[IMT_min, IMT_max], rtol=rtol, method=method)
+        gm_est = output.root
+        
+    except Exception as error:
+        logger.error(f"An exception occurred: {error}")
+        logger.info("Set ground motion value to nan")
+        gm_est = np.nan
+        
+    end = timer()
+    logger.info(f"Ground motion estimation computation time: {round(end - start,1)} seconds")
+    logger.info(f"Estimated {imt}: {gm_est}")  
+    
+    return gm_est
+
 def main(catalog_file, mc_file, pdf_file, m_file, m_select, mag_label, mc, m_max,
          m_kde_method, xy_select, grid_dim, xy_win_method, rate_select, time_win_duration,
          forecast_select, custom_rate, forecast_len, time_unit, model, products_string, verbose):
@@ -64,7 +243,7 @@ def main(catalog_file, mc_file, pdf_file, m_file, m_select, mag_label, mc, m_max
     from igfash.io import read_mat_cat, read_mat_m, read_mat_mc, read_mat_pdf, read_csv
     from igfash.window import win_CTL, win_CNE
     import igfash.kde as kde
-    from igfash.gm import compute_IMT_exceedance
+    #from igfash.gm import compute_IMT_exceedance
     from igfash.compute import get_cdf, hellinger_dist, cols_to_rows
     from igfash.rate import lambda_probs, calc_bins, bootstrap_forecast_rolling
     from igfash.mc import estimate_mc