July 25, 1970 Tsunami: Seikaido, Japan

Name: July 25, 1970 Tsunami: Seikaido, Japan
Start: 1970-07-25
Location: Seikaido, Japan

July 25, 1970 · 0.32 m · Definite tsunami

A tsunami caused by a magnitude 7 earthquake began at Seikaido, Japan on July 25, 1970 at 22:41:10 UTC. The water rose as high as 0.32 meters. Its effects were recorded at 35 places.

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

The tsunami

Date: July 25, 1970, 22:41:10 UTC
Source: Seikaido, Japan
Cause: Earthquake
Earthquake: Magnitude 7, 34 km deep
Maximum water height: 0.32 m (1.0 ft)
Runups recorded: 35
Tsunami magnitude (Iida): -0.7
Waters: Ocean
How certain: Definite tsunami
Source location: 32.200° N, 131.700° E

The toll

Injuries: 13 with the earthquake or eruption that caused it
Damage: Limited (under about $1 million) with the earthquake or eruption that caused it

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.

July 26. 197Q. At approximately 07hr 41min [local time] an earthquake was felt throughout an extensive area of southern Japan. After this earthquake, a weak tsunami was observed in the south of Japan. According to tide gauge records, the tsunami began with a rise in water level on the coasts of Kyushyu and Shikoku Islands about 15 min after the earthquake and for the most part had an amplitude of about 10 cm and a period of 20 min. (reference #417)

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	Measured by
Hososhima	Japan	26	0.06	Tide gauge (half the maximum wave height)
Tomi	Japan	44	0.02	Tide gauge (half the maximum wave height)
Miyanoura	Japan	55	0.12	Tide gauge (half the maximum wave height)
Kamaegyoko	Japan	70	0.19	Tide gauge (half the maximum wave height)
Aburatsu	Japan	73	0.2	Tide gauge (half the maximum wave height)
Mishoko	Japan	81	0.13	Tide gauge (half the maximum wave height)
Saikiko	Japan	87	0.09	Tide gauge (half the maximum wave height)
Fukushima	Japan	93	0.06	Tide gauge (half the maximum wave height)
Oita	Japan	118	0.02	Tide gauge (half the maximum wave height)
Saganoseki	Japan	118	0.02	Tide gauge (half the maximum wave height)
Sukumo	Japan	127	0.1	Tide gauge (half the maximum wave height)
Tosa-Shimizu	Japan	135	0.23	Tide gauge (half the maximum wave height)
Misakiko	Japan	137	0.11	Tide gauge (half the maximum wave height)
Uwajima	Japan	140	0.04	Tide gauge (half the maximum wave height)
Shimoda	Japan	147	0.04	Tide gauge (half the maximum wave height)
Yawatahama	Japan	154	0.06	Tide gauge (half the maximum wave height)
Kamikawaguchiko	Japan	156	0.13	Tide gauge (half the maximum wave height)
Odomari	Japan	163	0.16
Odomari	Japan	163	0.16	Tide gauge (half the maximum wave height)
Kataura	Japan	168	0.12
Makurazaki	Japan	168	0.13	Tide gauge (half the maximum wave height)
Ehime-Misaki	Japan	169	0.11
Tosa-Shimoda	Japan	218	0.03	Tide gauge (half the maximum wave height)
Kochi	Japan	229	0.02	Tide gauge (half the maximum wave height)
Murotomisaki	Japan	260	0.28	Tide gauge (half the maximum wave height)
Kannoura	Japan	286	0.32	Tide gauge (half the maximum wave height)
Kannoura (Toyocho)	Japan	286	0.32	Tide gauge (half the maximum wave height)
Kushimoto	Japan	407	0.09	Tide gauge (half the maximum wave height)
Uragami	Japan	421	0.04	Tide gauge (half the maximum wave height)
Owase	Japan	469	0.04	Tide gauge (half the maximum wave height)
Naze	Japan	473	0.04	Tide gauge (half the maximum wave height)
Omaezaki	Japan	663	0.05	Tide gauge (half the maximum wave height)
Minami-Izu	Japan	720	0.03	Tide gauge (half the maximum wave height)
Kozushima	Japan	728	0.03	Tide gauge (half the maximum wave height)
Mera	Japan	812	0.04	Tide gauge (half the maximum wave height)

Every tsunami in 1970 The 1900s 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 2025.