September 20, 2024 Tsunami: Surprise Inlet, AK, United States
A tsunami caused by a landslide began at Surprise Inlet, AK, United States on September 20, 2024. The water rose as high as 0.04 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
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
- September 20, 2024
- Source
- Surprise Inlet, AK, United States
- Cause
- Landslide
- Maximum water height
- 0.04 m (0.1 ft)
- Runups recorded
- 1
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 61.064° N, 148.430° W
The toll
The record gives no deaths, injuries or damage for this tsunami.
What the record says
NCEI’s account, from the sources it cites.
As part of ongoing experimental monitoring in Prince William Sound, we detected three large landslides (0.5–2.3Mm3) at Surprise Inlet on 20 September 2024, within the span of an hour. These events were identified in near real‐time through seismic data and later confirmed using satellite imagery, tidal records, and infrasound. The landslides generated a modest tsunami, and a 4 cm wave was recorded by a tide gauge 18 km away, marking the first recorded landslide to reach water since monitoring began in this region in 2021 […] The detections began at 11:12 UTC. The first detected landslide (L1) lasted about a minute with an estimated volume of 0.7Mm3 (reference #14472)
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 |
|---|---|---|---|---|---|---|---|
| Barry Arm Point Doran, AK, AK | United States | 14 | 0.04 | Tide gauge (half the maximum wave height) |
More
Every tsunami in 2024The 2000sTsunamis of United StatesThis day in weather historyAlerts 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 6185.