Reviewed by USGSAlaska98y ago
M6.0 earthquake 75 km SW of Adak, Alaska
Monday, July 8, 1929, 19:08:56 UTC · 51.479°N, 177.523°W
A magnitude 6.0 earthquake struck 75 km SW of Adak, Alaska on Monday, July 8, 1929, 19:08:56 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M6.0 on July 8, 1929.
- Magnitude
- 6.0
- Moderate · mw
- Depth
- 35 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: 75 km aftershock search area
In context
How big was it, and why here?
Energy released
13 kilotons of TNT
That is about the energy of the Hiroshima bomb. It released about 28 times the energy of a magnitude 5.0.
Tectonic setting
110 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
35 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 75 km
USGS lists 2 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M6.0 on July 11, 1929. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 54 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 299 km W of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 73 km NE of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 15 km W of this epicenter
- 7.2238 km WSW of Adak, AlaskaMarch 22, 1905 · 167 km W of this epicenter
- 7.0Rat Islands, Aleutian Islands, AlaskaFebruary 6, 1916 · 252 km W of this epicenter
- 7.0101 km S of Adak, AlaskaSeptember 9, 1910 · 99 km SE of this epicenter
- 7.0114 km WSW of Adak, AlaskaJuly 5, 1929 · 44 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 2 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1906M8.3
Aleutian Islands: Rat Islands
17 Aug 1906 · 299 km away
- 1905M7.9
Andreanof Islands
14 Feb 1905 · 110 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.