May 7, 1986 Earthquake: Adak, Aleutian Islands, Alaska, United States

Name: May 7, 1986 Earthquake: Adak, Aleutian Islands, Alaska, United States
Start: 1986-05-07
Location: Adak, Aleutian Islands, Alaska, United States

May 7, 1986 · M8

A magnitude 8 earthquake struck Adak, Aleutian Islands, Alaska, United States on May 7, 1986 at 22:47:10 UTC, 19 km below the surface. It caused a tsunami.

Map

Where it struck, with the other significant earthquakes within 200 km. Circles are sized and colored by magnitude; select one for its page.

The earthquake

Date: May 7, 1986
Time: 22:47:10 UTC
Place: Adak, Aleutian Islands, Alaska, United States
Magnitude: 8 (Mw)
Focal depth: 19 km (12 mi)
Intensity: 6 on the Modified Mercalli scale
Tsunami: Yes: the tsunami it caused
Epicenter: 51.520° N, 174.776° W
Country: United States

The toll

Damage: Moderate (about $1 to $5 million)
Houses damaged: Some (about 51 to 100)

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.

1986, May 7, 22:47:10.8 UTC. Multiple event. Damage (VI) on Adak and Atka. Tsunami generated. (reference #1053)

1986. May 7, 22 47 UTC. Andreanof Islands,

Aleutian Islands, Alaska. This earthquake caused

moderate damage to structures on Adak Island and

slight damage on Atka Island. Damage to buildings

on Adak Island consisted of cracked masonry and

concrete walls, failure of partitions and suspended

ceilings, spalling on concrete beams and piers, and

differential settlement of house foundations. Soil liquefaction was observed in localized areas of backfilled

soil, and sand boils were observed. Laterally spreading cracks and differential ground settlement occurred along a small wharf. This earthquake caused a small tsunami that was recorded throughout the Pacific Ocean. Magnitude 7.9 MS BRK. (Ref. 562, 610. (reference #542)

Other significant earthquakes nearby

Within 200 km, the deadliest first.

Significant earthquakes of 1986 The 1900s Every quake the USGS located in 1986 Recent earthquakes near here This day in weather history

Sources

Significant earthquakes 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 earthquake 5095.