Reviewed by USGSAlaska40y ago
M4.9 earthquake 69 km SW of Adak, Alaska
Sunday, January 4, 1987, 00:05:38 UTC · 51.402°N, 177.294°W
A magnitude 4.9 earthquake struck 69 km SW of Adak, Alaska on Sunday, January 4, 1987, 00:05:38 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M4.9 on December 24, 1986.
- Magnitude
- 4.9
- 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 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
100 km
from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
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 578 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.71965 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeFebruary 4, 1965 · 278 km W of this epicenter
- 8.61957 Atka, Alaska EarthquakeMarch 9, 1957 · 116 km E of this epicenter
- 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 175 km E of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 68 km NE of this epicenter
- 7.4265 km WSW of Adak, AlaskaFebruary 4, 1965 · 216 km W of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 32 km W of this epicenter
- 7.2238 km WSW of Adak, AlaskaMarch 22, 1905 · 181 km W of this epicenter
- 7.2162 km WSW of Adak, AlaskaMarch 16, 1957 · 109 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 8 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 · 116 km away
2 deathsSevere damage ($5–24M)tsunami
- 1986M8.0
Aleutian Islands: Adak
7 May 1986 · 175 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1965M8.7
Aleutian Islands: Rat Islands
4 Feb 1965 · 278 km away · intensity VI
Under $1 million damagetsunami
- 1905M7.9
Andreanof Islands
14 Feb 1905 · 115 km away
- 1971M7.1
Andreanof Islands
2 May 1971 · 7 km away · intensity VI
tsunami
- 1986M6.4
Andreanof Islands
17 May 1986 · 217 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.