The tsunami event may have been destructive or non-destructive. If the event is non-destructive, local emergency management agencies may issue an "all clear" that it is safe to return to coastal areas. If a destructive event has occurred, an all clear may not be issued for hours to days. Emergency search and rescue operations will immediately commence on land and at sea. The coastline could be devastated with flooding, damaged homes / buildings, debris, fires, HAZMAT spills and inoperable utility lifeline systems (electrical, telecommunications, roadways / bridges, natural gas lines, etc.) The public will not be able to re-enter the coastline at least until roadway debris is removed. If tsunami was generated by a local earthquake, be alert for aftershocks and stay tuned to local radio and television broadcasts for emergency information and recovery assistance. Follow official instructions, using battery powered radios, regarding the opening of long term public shelters and/or disaster assistance centers. Remember, stay away from the coast until local officials issue an "all clear" reopening the area for you to return.
Post Tsunami Field Surveys will also commence to measure wave impacts on land (horizontal inundation and vertical runup heights).
The IOC Post-Tsunami Field Survey Guide was published in 1998 to provide governments and the scientific community with guidance on collecting perishable tsunami data immediately after the event. In 2014, the IOC published its revised Field Survey Guide to take into account the improvements in instrumentation and methods, needs to include the social and economic sciences, ecology, engineering, and other disciplines as importants part of post-tsunami surveys, and starting with the 2004 Indian Ocean tsunami, the significant increase in interest of many scientists to conduct surveys.
Post-tsunami survey field guide, IOC Manuals and Guides No. 37, 1998
International Tsunami Survey Team (ITST) Post-Tsunami Survey Field Guide. 2nd Edition, IOC Manuals and Guides No. 37, 2014
For examples of international tsunami survey teams (ITST) results, click here.
Additional useful information can be found on the US 'After a Tsunami' site
https://www.weather.gov/safety/tsunami-after