October 19, 2020 Tsunami: Shumagin Islands, AK, United States
A tsunami caused by a magnitude 7.6 earthquake began at Shumagin Islands, AK, United States on October 19, 2020 at 20:54:39 UTC. The water rose as high as 0.76 meters. Its effects were recorded at 33 places in at least 2 countries.
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
- October 19, 2020, 20:54:39 UTC
- Source
- Shumagin Islands, AK, United States
- Cause
- Earthquake
- Earthquake
- Magnitude 7.6, 28 km deep
- Maximum water height
- 0.76 m (2.5 ft)
- Runups recorded
- 33
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 54.602° N, 159.626° 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.
On October 19, 2020, the moment magnitude (Mw) 7.6 Sand Point earthquake struck south of the Shumagin Islands in Alaska. Moment tensors indicate the earthquake was primarily strike-slip, yet the event produced an enigmatic tsunami that was larger and more widespread than expected for an earthquake of that magnitude and mechanism […] we confirm that a simple strike-slip earthquake cannot generate the observed far-reaching tsunami. Instead, ocean height observations are consistent with a typical tsunamigenic megathrust earthquake, characterized by vertical motion at the subduction interface (reference #14337)
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 |
|---|---|---|---|---|---|---|---|
| Sand Point, AK, AK | United States | 99 | 0.7 | Tide gauge (half the maximum wave height) | |||
| King Cove, AK, AK | United States | 181 | 0.64 | Tide gauge (half the maximum wave height) | |||
| Chignik, AK, AK | United States | 206 | 0.76 | Tide gauge (half the maximum wave height) | |||
| Unalaska, Dutch Harbor, AK, AK | United States | 457 | 0.09 | Tide gauge (half the maximum wave height) | |||
| D46414 Bpr, SE of Chirikof Is, AK, AK | United States | 476 | 0.03 | Deep ocean gauge (half the maximum wave height) | |||
| D46402 Bpr, S of Dutch Harbor, AK, AK | United States | 492 | 0.04 | Deep ocean gauge (half the maximum wave height) | |||
| Nikolski, AK, AK | United States | 636 | 0.09 | Tide gauge (half the maximum wave height) | |||
| D46409 Bpr, SE of Kodiak, AK, AK | United States | 716 | 0.01 | Deep ocean gauge (half the maximum wave height) | |||
| Atka Island, AK, AK | United States | 1,000 | 0.06 | Tide gauge (half the maximum wave height) | |||
| Henslung Cove, British Columbia, BC | Canada | 1,719 | 0.06 | Tide gauge (half the maximum wave height) | day 19, 23:13 | ||
| Masset, British Columbia, BC | Canada | 1,778 | 0.03 | Tide gauge (half the maximum wave height) | day 19, 23:52 | ||
| Queen Charlotte, British Columbia, BC | Canada | 1,804 | 0.01 | Tide gauge (half the maximum wave height) | day 20, 02:57 | ||
| Bonilla Island, British Columbia, BC | Canada | 1,889 | 0.01 | Tide gauge (half the maximum wave height) | |||
| Rose Harbor, British Columbia, BC | Canada | 1,906 | 0.04 | Tide gauge (half the maximum wave height) | day 20, 00:10 | ||
| Hartley Bay, British Columbia, BC | Canada | 1,980 | 0.01 | Tide gauge (half the maximum wave height) | day 20, 03:17 | ||
| Bella Bella, British Columbia, BC | Canada | 2,094 | 0.02 | Tide gauge (half the maximum wave height) | day 20, 00:56 | ||
| Pruth Bay, British Columbia, BC | Canada | 2,115 | 0.03 | Tide gauge (half the maximum wave height) | day 20, 01:14 | ||
| Winter Harbor, British Columbia, BC | Canada | 2,171 | 0.08 | Tide gauge (half the maximum wave height) | day 20, 00:42 | ||
| Port Hardy, British Columbia, BC | Canada | 2,197 | 0.01 | Tide gauge (half the maximum wave height) | day 20, 01:11 | ||
| Tofino (Clayoquot),british Columbia, BC | Canada | 2,374 | 0.07 | Tide gauge (half the maximum wave height) | day 20, 01:14 | ||
| Ucluelet, British Columbia, BC | Canada | 2,408 | 0.08 | Tide gauge (half the maximum wave height) | day 20, 01:21 | ||
| Port Alberni, British Columbia, BC | Canada | 2,441 | 0.07 | Tide gauge (half the maximum wave height) | day 20, 01:58 | ||
| Bamfield, British Columbia, BC | Canada | 2,441 | 0.03 | Tide gauge (half the maximum wave height) | day 20, 01:27 | ||
| Port Renfrew, British Columbia, BC | Canada | 2,503 | 0.08 | Tide gauge (half the maximum wave height) | day 20, 01:34 | ||
| Victoria, British Columbia, BC | Canada | 2,577 | 0.02 | Tide gauge (half the maximum wave height) | day 20, 02:19 | ||
| Crescent City, CA, CA | United States | 2,955 | 0.21 | Tide gauge (half the maximum wave height) | |||
| Hanalei, Kauai, HI, HI | United States | 3,596 | 0.26 | Tide gauge (half the maximum wave height) | |||
| Nawiliwili, Kauai, HI, HI | United States | 3,624 | 0.09 | Tide gauge (half the maximum wave height) | |||
| Haleiwa, Oahu, HI, HI | United States | 3,666 | 0.19 | Tide gauge (half the maximum wave height) | |||
| Mokuoloe-Coconut Is, Oahu, HI | United States | 3,685 | 0.02 | Tide gauge (half the maximum wave height) | |||
| Kahului, Maui, HI, HI | United States | 3,751 | 0.13 | Tide gauge (half the maximum wave height) | |||
| Kawaihae, Hawaii, HI, HI | United States | 3,850 | 0.05 | Tide gauge (half the maximum wave height) | |||
| Hilo, Hawaii, HI, HI | United States | 3,890 | 0.28 | Tide gauge (half the maximum wave height) |
More
Every tsunami in 2020The 2000sTsunamis of United StatesThe earthquakeThis 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 5755.