This paper presents a novel approach to characterization of liquefaction susceptibility for deposits of saturated cohesionless soils. The method we propose is based on an assumed relationship between pore pressure increase and dissipated energy density within the soil layer. Use of dissipated energy is not new. What makes the present work different is our approach to the energy calculation. Earlier analyses used simple attenuation models based on earthquake magnitude and epicentral distance to determine the dissipated energy and hence the pore pressure increase within a sand deposit. In this work, instead of magnitude and distance, we will use the response spectrum for surface motion at the site as input information. This permits us to carry out liquefaction susceptibility analyses which are more closely aligned with other types of analyses such as structural response. In particular, we can employ code-prescribed spectral loads exactly as are used by structural designers. This leads to an analysis of liquefaction which is consistent with other earthquake engineering practice in New Zealand.