O-HELP (Oregon Hazard Explorer for Lifelines Program) is a user-friendly, web-based geographic information system (GIS) tool to assess potential earthquake hazards in Oregon, developed with support from the Cascadia Lifelines Program (CLiP) by the Oregon State University College of Engineering . The mapping and reporting tool contains previously mapped hazard information on severe ground shaking, landslides, liquefaction and lateral spreading, co-seismic subsidence, and potential tsunami inundation lines. This tool is designed for engineers, planners, geologists, and others who need this information to help make appropriate decisions. It is assumed that the users have enough knowledge about earthquake engineering and geologic hazards to understand what the data means and how to use it appropriately.