Reviewed by USGSAlaska101y ago
M6.9 earthquake 100 km ESE of Adak, Alaska
Wednesday, October 13, 1926, 19:08:18 UTC · 51.524°N, 175.295°W
A magnitude 6.9 earthquake struck 100 km ESE of Adak, Alaska on Wednesday, October 13, 1926, 19:08:18 UTC, at a depth of 40.0 km (shallow). It is the strongest earthquake within 300 km since an M7.0 on September 9, 1910.
- Magnitude
- 6.9
- Strong · mw
- Depth
- 40 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: 100 km aftershock search area
In context
How big was it, and why here?
Energy released
349 kilotons of TNT
That is about 23 times the Hiroshima bomb. It released about 733 times the energy of a magnitude 5.0.
Tectonic setting
80 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
40 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 100 km
USGS lists 1 M2.5+ earthquake within 100 km in the following 30 days; the largest was M6.0 on October 14, 1926. 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 25 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 105 km NW of this epicenter
- 7.0101 km S of Adak, AlaskaSeptember 9, 1910 · 95 km SW of this epicenter
- 6.9182 km SSE of Atka, AlaskaJanuary 27, 1906 · 191 km SE of this epicenter
- 6.9203 km WSW of Adak, AlaskaMarch 31, 1913 · 289 km W of this epicenter
- 6.9216 km SSE of Adak, AlaskaSeptember 17, 1911 · 156 km S of this epicenter
- 6.8Andreanof Islands, Aleutian Islands, AlaskaJune 22, 1913 · 293 km SW 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:
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 296 km away
Limited damage (under $1M)tsunami
- 1905M7.9
Andreanof Islands
14 Feb 1905 · 244 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.