Reviewed by USGSAlaska40y ago
M4.4 earthquake 109 km SW of Atka, Alaska
Sunday, June 22, 1986, 15:35:21 UTC · 51.431°N, 175.203°W
A magnitude 4.4 earthquake struck 109 km SW of Atka, Alaska on Sunday, June 22, 1986, 15:35:21 UTC, at a depth of 33.0 km (shallow).
- Magnitude
- 4.4
- Light · mb
- Depth
- 33 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
60 tons of TNT
That is about 1/251 of the Hiroshima bomb. A magnitude 5.0 releases about 8 times more energy.
Tectonic setting
69 km
from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
33 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 50 km
USGS lists 7 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.9 on July 4, 1986. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 4.879 km SE of Adak, Alaska40y ago · 35 km W of this epicenter
- 4.0101 km SW of Atka, Alaska40y ago · 8 km N of this epicenter
- 4.888 km SSW of Atka, Alaska40y ago · 43 km E of this epicenter
- 4.5Andreanof Islands, Aleutian Islands, Alaska40y ago · 5 km SE of this epicenter
- 4.975 km ESE of Adak, Alaska40y ago · 36 km W of this epicenter
- 4.383 km SW of Atka, Alaska40y ago · 32 km N of this epicenter
- 4.6101 km SE of Adak, Alaska40y ago · 39 km SW of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 508 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.61957 Atka, Alaska EarthquakeMarch 9, 1957 · 30 km W of this epicenter
- 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 31 km E of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 115 km NW of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 176 km W of this epicenter
- 7.2162 km WSW of Adak, AlaskaMarch 16, 1957 · 254 km W of this epicenter
- 7.175 km S of Adak, AlaskaMarch 14, 1957 · 110 km W of this epicenter
- 7.160 km SW of Adak, AlaskaMarch 12, 1957 · 141 km W of this epicenter
- 7.158 km WNW of Atka, AlaskaFebruary 28, 1970 · 119 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 7 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2 recorded deaths. The most severe:
- 1957M8.6
Alaska
9 Mar 1957 · 30 km away
2 deathsSevere damage ($5–24M)tsunami
- 1986M8.0
Aleutian Islands: Adak
7 May 1986 · 31 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 290 km away
Limited damage (under $1M)tsunami
- 1905M7.9
Andreanof Islands
14 Feb 1905 · 246 km away
- 1971M7.1
Andreanof Islands
2 May 1971 · 139 km away · intensity VI
tsunami
- 1986M6.4
Andreanof Islands
17 May 1986 · 111 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.