Reviewed by USGSAlaska40y ago
M4.9 earthquake 80 km SSE of Atka, Alaska
Wednesday, June 18, 1986, 03:30:08 UTC · 51.508°N, 173.847°W
A magnitude 4.9 earthquake struck 80 km SSE of Atka, Alaska on Wednesday, June 18, 1986, 03:30:08 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M5.3 on June 5, 1986.
- Magnitude
- 4.9
- Light · ms
- 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 earthquake
In context
How big was it, and why here?
Energy released
338 tons of TNT
That is about 1/45 of the Hiroshima bomb. A magnitude 5.0 releases about 1 times more energy.
Tectonic setting
64 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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 451 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 · 123 km W of this epicenter
- 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 64 km W of this epicenter
- 7.8234 km SSW of Nikolski, AlaskaMarch 7, 1929 · 291 km E of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 201 km W of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 270 km W of this epicenter
- 7.175 km S of Adak, AlaskaMarch 14, 1957 · 203 km W of this epicenter
- 7.160 km SW of Adak, AlaskaMarch 12, 1957 · 235 km W of this epicenter
- 7.158 km WNW of Atka, AlaskaFebruary 28, 1970 · 131 km NW 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 · 123 km away
2 deathsSevere damage ($5–24M)tsunami
- 1986M8.0
Aleutian Islands: Adak
7 May 1986 · 64 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 196 km away
Limited damage (under $1M)tsunami
- 1929M7.8
Aleutian Islands: Fox Islands
7 Mar 1929 · 274 km away · intensity V
tsunami
- 1971M7.1
Andreanof Islands
2 May 1971 · 233 km away · intensity VI
tsunami
- 1986M6.4
Andreanof Islands
17 May 1986 · 102 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.