def select_catalogue(self, selector, distance=None):
        '''
        Selects the catalogue of earthquakes attributable to the source

        :param selector:
            Populated instance of openquake.hmtk.seismicity.selector.CatalogueSelector
            class
        :param float distance:
            Distance (in km) to extend or contract (if negative) the zone for
            selecting events
        '''
        if selector.catalogue.get_number_events() < 1:
            raise ValueError('No events found in catalogue!')

        self.catalogue = selector.within_polygon(self.geometry,
                                                 distance,
                                                 upper_depth=self.upper_depth,
                                                 lower_depth=self.lower_depth)
        if self.catalogue.get_number_events() < 5:
            # Throw a warning regarding the small number of earthquakes in
            # the source!
            warnings.warn('Source %s (%s) has fewer than 5 events'
                          % (self.id, self.name))
Selects the catalogue of earthquakes attributable to the source

        :param selector:
            Populated instance of openquake.hmtk.seismicity.selector.CatalogueSelector
            class
        :param float distance:
            Distance (in km) to extend or contract (if negative) the zone for
            selecting events