This is a Call for Participation to research scientists, geodetic research groups and national agencies in support of the implementation of the recommended Global Navigation Satellite System (GNSS) Augmentation to Tsunami Early Warning Systems (GATEW). The call seeks to establish a working group to be a catalyst and motivating force for the definition of requirements, identification of resources, and for the encouragement of international cooperation in the establishment, advancement, and utilization of GNSS for Tsunami Early Warning.