Twice in fourteen years, waves born thousands of kilometres away swept into Hilo Bay. They killed 157 people in the town, wiped out whole neighbourhoods and taught the Pacific how to warn of tsunamis.
1 April 1946: a morning at Laupāhoehoe
On the morning of Monday 1 April 1946, children were gathering at the school on Laupāhoehoe Point, a flat tongue of lava on the Hāmākua Coast north of Hilo. Survivors remember the sea pulling back, exposing reef and stranded fish. Then the water came back.
A series of waves, estimated at about 15 m (50 ft) high at Laupāhoehoe, swept over the point. Twenty-four people there were killed, among them 16 students and 5 teachers. A memorial on the point lists their names, and the school later moved to higher ground.
Because it struck on 1 April, many people in Hawaiʻi still call it the April Fools' Day tsunami. There was nothing funny about it: it remains the deadliest tsunami in Hawaiʻi's recorded history.
A wave from Alaska
The cause lay more than 3,500 km (2,200 mi) to the north. Early that morning a great earthquake struck the Aleutian Trench off Unimak Island, Alaska. Within an hour a wave about 30 m (100 ft) high destroyed the Scotch Cap lighthouse on Unimak, killing all five keepers.
No one warned Hawaiʻi. The waves crossed the Pacific at the speed of a jet aircraft and reached Hilo about five hours after the quake, around 7 am. Witnesses on the bayfront estimated the largest waves at 10–15 m (35–50 ft).
The bayfront business district was smashed. Trains of the Hawaiʻi Consolidated Railway were overturned and the depot destroyed, and the railway never ran again; part of its line north of Hilo later became the route of the highway. The largely Japanese neighbourhood of Shinmachi, on low ground by the bay, took the worst of it. An army crash boat was found about 120 m (400 ft) inland.
Across the islands, 159 people died, 96 of them in Hilo. Damage was put at about $26 million at the time.
Building a warning system
The disaster forced a change. In 1949 the US Coast and Geodetic Survey set up the Seismic Sea Wave Warning System at ʻEwa Beach on Oʻahu, linking seismographs and tide gauges around the Pacific. When a large earthquake struck, scientists could now estimate when waves would arrive and send alerts ahead of them. The centre became today's Pacific Tsunami Warning Center.
Hilo rebuilt much of its bayfront, including Shinmachi, in the same low-lying places. Within fourteen years, the new system and the rebuilt town would both be tested.
22 May 1960: a warning that went unheeded
On 22 May 1960 the largest earthquake ever recorded, magnitude 9.5, struck southern Chile. At 6.47 that evening, Hawaiian time, the warning centre announced that waves should reach Hilo around midnight. Coastal sirens sounded at 8.30 pm.
Many people left, but hundreds stayed in their homes on low ground. Some were unsure what the sirens meant; others remembered that earlier warnings had brought only small waves. The first waves after midnight were just 1–2 m (a few feet) high, and some people who had evacuated drove back down to the bayfront to watch.
The third and largest wave struck shortly after 1 am on 23 May. At the Wailuku River bridge the USGS seismologist Jerry Eaton and his companions measured it at about 4.3 m (14 ft), but it surged much higher where it was funnelled ashore. It flattened the town of Waiākea and the rebuilt Shinmachi.
In Hilo, 61 people died. The waves went on across the ocean and killed 122 people in Japan.
The clock that stopped at 1.04
On Kamehameha Avenue stands a clock that came from the Waiākea Social Settlement building, a few hundred metres away. The wave that destroyed it stopped its hands at 1.04 am. It has become Hilo's best-known tsunami memorial, though it sits on a stretch of road where it is hard to stop; in 2026 the state set aside funds to move it somewhere with parking and a storyboard.
Waiākea town was never rebuilt. Its school, Waiākea Kai, reopened on higher ground, and families and businesses moved inland or uphill.
A town that moved uphill
After 1960, Hilo decided not to rebuild in the most dangerous places. Low ground on the Waiākea peninsula and along the bay was turned into parks and open space as a buffer against future waves. Wailoa River State Recreation Area, created in 1969, covers about 53 ha (132 acres) of that land and holds a memorial to Shinmachi.
Downtown Hilo, set slightly back from the water, survived as the town's historic heart, and from the 1980s its old shopfronts filled with galleries and museums. For visitors it is easy to miss that the wide lawns along the bay are, in effect, a memorial landscape.
| 1946 | 1960 | |
|---|---|---|
| Source | Aleutian Islands, Alaska | Southern Chile, magnitude 9.5 |
| Arrival in Hilo | Shortly before 7 am, 1 April | After midnight, 23 May |
| Warning | None | Several hours; sirens at 8.30 pm |
| Deaths in Hilo | 96 (159 statewide) | 61 |
Remembering through stories
In the 1990s a survivor of 1946, Jeanne Branch Johnston, and the oceanographer Walter Dudley set out to record survivors' memories before they were lost. The Pacific Tsunami Museum they co-founded opened in 1998 in a former First Hawaiian Bank building of 1930, designed by the Honolulu architect C. W. Dickey, on the corner of Kamehameha Avenue and Kalākaua Street.
Its exhibits pair photographs and survivors' accounts of 1946 and 1960 with lessons from later disasters, including the Indian Ocean tsunami of 2004. The museum's message is simple: if the ground shakes hard or the sea suddenly retreats, go to high ground at once and stay there until the all-clear.
Visiting Hilo's tsunami sites
- Pacific Tsunami Museum: 130 Kamehameha Avenue. Its website lists daily opening, 10 am to 4 pm, but the museum has relied on volunteers and donations since funding problems in late 2024, so check tsunami.org before you go.
- Waiākea clock: on Kamehameha Avenue at the edge of the Naniloa golf course; it may be moved, so ask at the museum.
- Wailoa River State Recreation Area: lawns, footbridges and the Shinmachi memorial on the old waterfront.
- Laupāhoehoe Point: about 45 minutes north of Hilo on the Hāmākua Coast, with the memorial to those lost in 1946.
Hilo pairs naturally with the volcano story in Kīlauea's eruption history and the wider island guide in things to do on the Big Island. Before swimming anywhere, read our advice on Hawaiʻi ocean safety. The town's rebuilding sits within the post-war chapters of The History of Hawaii, alongside statehood, which came just months before the 1960 waves, and the wartime story of the Japanese American families who filled neighbourhoods like Shinmachi, told in Japanese Americans in Hawaiʻi in the Second World War.
Quick answers
How many people died in the 1946 Hilo tsunami?
The tsunami of 1 April 1946 killed 159 people across Hawaiʻi, 96 of them in Hilo. At Laupāhoehoe, 24 people died, including 16 students and 5 teachers.
Why is it called the April Fools' Day tsunami?
Because it struck on 1 April 1946. The waves were caused by a great earthquake off the Aleutian Islands of Alaska and reached Hilo about five hours later, with no warning.
How many people died in the 1960 Hilo tsunami?
The tsunami from the magnitude 9.5 Chile earthquake killed 61 people in Hilo on 23 May 1960, even though sirens had sounded hours earlier. Many people stayed on low ground or returned after the first small waves.
What does the Hilo tsunami clock show?
The Waiākea clock stopped at 1.04 am on 23 May 1960, when the third and largest wave of the Chile tsunami destroyed it. It stands on Kamehameha Avenue as a memorial.
Is the Pacific Tsunami Museum open?
Its website lists daily hours of 10 am to 4 pm at 130 Kamehameha Avenue, Hilo. The museum has faced funding problems since late 2024 and relies on volunteers, so check tsunami.org before visiting.
Facts checked October 2026 against the sources below and the research for our book The History of Hawaii. Dates and figures for early Hawaiian history are estimates and scholars still debate some of them.
- A wall of water: survivors reflect on devastating tsunami that struck Hilo 75 years ago (Hawaii Tribune-Herald)
- Accounts from Hawaii's 1946 tsunami (Shaka Guide)
- Benchmarks: April 1, 1946: Hawaii tsunami ushers in a Pacific-wide warning system (EARTH Magazine)
- Volcano Watch: Golden anniversary of Chilean earthquake comes early (USGS)
- Waiākea Kai Clock (Pacific Tsunami Museum)
- Tsunami museum in trouble: downtown Hilo site closes due to financial woes (Hawaii Tribune-Herald)
- Hilo tsunami clock memorial may be relocated (The Garden Island)
- Wailoa River State Recreation Area (Wikipedia)
