July 22, 1768 Tsunami: Ryukyu Islands, Japan

Name: July 22, 1768 Tsunami: Ryukyu Islands, Japan
Start: 1768-07-22
Location: Ryukyu Islands, Japan

July 22, 1768 · 1.2 m · 9 houses destroyed · Definite tsunami

A tsunami caused by a magnitude 6.5 earthquake began at Ryukyu Islands, Japan on July 22, 1768. The water rose as high as 1.2 meters. Its effects were recorded at 1 place.

Where the waves reached

The source (white) and every runup with a place, colored by the water height recorded there. A ring is a runup NCEI marks doubtful.

Under 1 m
1 to 3 m
3 to 10 m
10 to 30 m
30 m and more
Height not recorded

Tsunami warnings in force

Travel times

How long the first wave took to reach each part of the ocean, one line for each hour up to 24, estimated from the source and the depth of the sea.

The travel times are computed in your browser, which needs JavaScript.

1 to 4 hours
5 to 6 hours
7 to 14 hours
15 hours and more

Computed in your browser the way NOAA’s own travel time maps are: the wave travels at the square root of gravity times the depth, over NOAA’s ETOPO1 depths averaged to a 10 arc-minute grid. Checked against NOAA NCEI’s maps for 21 tsunamis over the first 24 hours, these lines fall within 10 minutes of NCEI’s at half the points compared and within 52 minutes at 9 in 10. They give when the first wave could arrive, not how high it is; bays, harbors and island chains finer than the grid can see it later. Not for use in a warning: see tsunami.gov.

The tsunami

Date: July 22, 1768
Source: Ryukyu Islands, Japan
Cause: Earthquake
Earthquake: Magnitude 6.5
Maximum water height: 1.2 m (3.9 ft)
Runups recorded: 1
Tsunami intensity (Soloviev-Imamura): 1
Tsunami magnitude (Iida): 0.3
Waters: Ocean
How certain: Definite tsunami
Source location: 26.200° N, 127.500° E

The toll

Damage: Limited (under about $1 million)
Houses destroyed: 9

Where the literature gives no number, NCEI records a description on a scale of 1 to 4, printed here in its words. Damage is in millions of US dollars of the year of the event, not adjusted for inflation.

What the record says

NCEI’s account, from the sources it cites.

Reference #414:

1768, July 22, 12:00 local time. Validity 3. A rather strong earthquake was felt at Shyuri (Okinawa Island), and afterwards a tsunami of height 0.6-1.2 m was observed on the coast. The damage was slight. Two or three waves were recorded. Nine villages suffered damage on the coast of the Kerama Islands. Nine homes were destroyed. Both the earthquake and the tsunami were weak.

Reference #150:

1768, July 22. 26.6 N, 127.5 E, magnitude 6.5. 9 houses and rice field damaged by tsunami in Kerama Is. Stone walls of King castle, tombs and temples collapsed. Tsunami height 1.2m at Zamami.

Reference #79:

1768, July 22. 26.2 N, 127.5 E. Near Kerama Is. 2 or 3 waves. 9 villages damaged. 9 houses destroyed.

Reference #3785:

1768, July 28, 13-14 local time, 26.2 N, 127.5 E.

Every runup

Nearest the source first. Heights are above sea level at the time; a tide gauge reads half the wave’s full height.

Where	Country	Km from source	Water height, m	Inland, m	Measured by	First wave, UTC	Deaths
Zamami, Kerama Islands	Japan	20	1.2		Eyewitness observation of water height

Every tsunami in 1768 The 1700s Tsunamis of Japan The earthquake This day in weather history Alerts in force

Sources

Tsunami events and runups from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-09-24. NCEI tsunami event 497.