The era of tsunami warnings began in the United States with Thomas Jaggar's (founder of the Hawaiian Volcano Observatory (HVO)) attempt to warn the Hilo harbormaster of the possibility of a tsunami generated by the 1923 Kamchatka earthquake. His warning was not taken seriously, and at least one fisherman was killed.
Official tsunami warning capability in the U.S. began in 1949 as a response to the 1946 tsunami generated in the Aleutian Islands that devastated Hilo. The U.S. federal government already had a sizable piece of property in ʻEwa Beach to house the Honolulu Geomagnetic Observatory. The Tsunami Warning Center was co-located with this facility, which is maintained by PTWC staff today.
In the aftermath of the 1960 Chilean earthquake and tsunami which devastated Chile, killed dozens in Hawaiʻi and perhaps as many as 200 people in Japan, the nations of the Pacific decided to coordinate efforts to prevent such loss of life from ever occurring again in the Pacific Basin due to destructive ocean-crossing tsunamis. Under the auspices of the United Nations, the Intergovernmental Oceanographic Commission (IOC) established the Intergovernmental Coordination Group for the Pacific Tsunami Warning System (ICG/PTWS) in 1968. The U.S. offered the ʻEwa Beach center as the operational headquarters for the Pacific Tsunami Warning System, and the facility was re named the Pacific Tsunami Warning Center.
PTWC issued tsunami warnings to Alaska until 1967 when the West Coast & Alaska Tsunami Warning Center (WC/ATWC) was established in response to the 1964 Alaskan earthquake and tsunami. In 1982, the WC/ATWC area of responsibility was enlarged to include the issuing of tsunami warnings to California, Oregon, Washington, and British Columbia for potential tsunamigenic earthquakes occurring in their coastal areas. PTWC continued to issue tsunami warnings to these areas for Pacific-wide tsunamigenic sources until 1996 when that responsibility was also given to the WC/ATWC.
Following the 1975 Kalapana earthquake and tsunami on Hawaiʻi's Big Island, PTWC began issuing official tsunami warnings to the state of Hawaiʻi for local earthquakes. In 2005, PTWC similarly began issuing local tsunami warnings to Puerto Rico and the U.S. Virgin Islands, but in June 2007 that area of responsibility passed to WC/ATWC.
PTWC was re-dedicated on December 1, 2001 as the "Richard H. Hagemeyer Pacific Tsunami Warning Center" in honor of the former U.S. Tsunami Program Manager and National Weather Service Pacific Region Director who managed PTWC for many years.
In the aftermath of the 2004 Indian Ocean tsunami, PTWC has taken on additional areas of responsibility including the Indian Ocean (until March 2013), South China Sea, Caribbean Sea, and Puerto Rico & U.S. Virgin Islands (until June 2007). PTWC's staff size has increased from 8 to 15 as a result of the tsunami, and it now staffs the center 24 hours per day everyday.