def get_area(self):
        '''
        Calculates the area of the fault (km ** 2.) as the product of length
        (km) and downdip width (km)
        '''
        d_z = self.lower_depth - self.upper_depth
        self.downdip_width = d_z / np.sin(self.dip * np.pi / 180.)
        self.surface_width = self.downdip_width * np.cos(self.dip *
                                                         np.pi / 180.)
        self.area = self.length * self.downdip_width
        return self.area
Calculates the area of the fault (km ** 2.) as the product of length
        (km) and downdip width (km)