Reviewed by USGSTonga100y ago
M5.9 earthquake 25 km SSW of ‘Ohonua, Tonga
Saturday, May 21, 1927, 16:53:38 UTC · 21.558°S, 175.011°W
A magnitude 5.9 earthquake struck 25 km SSW of ‘Ohonua, Tonga on Saturday, May 21, 1927, 16:53:38 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M5.9 on September 6, 1926.
- Magnitude
- 5.9
- 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 earthquake
In context
How big was it, and why here?
Energy released
11 kilotons of TNT
That is about the energy of the Hiroshima bomb. It released about 23 times the energy of a magnitude 5.0.
Tectonic setting
116 km
from the nearest mapped plate boundary, between the Tonga 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 has not published any M2.5+ earthquake within 75 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 14 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.0TongaJanuary 4, 1903 · 173 km N of this epicenter
- 7.8111 km SSE of Pangai, TongaJune 26, 1913 · 158 km NE of this epicenter
- 7.2241 km WNW of Houma, TongaAugust 21, 1911 · 291 km NW of this epicenter
- 6.915 km WSW of Pangai, TongaFebruary 27, 1905 · 195 km N of this epicenter
- 6.6110 km NW of Pangai, TongaJanuary 22, 1922 · 264 km N of this epicenter
- 6.577 km SSW of Pangai, TongaJune 24, 1917 · 129 km N of this epicenter
- 6.5TongaDecember 18, 1906 · 116 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 6 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1865M8.0
Tonga Islands
18 Nov 1865 · 278 km away
Limited damage (under $1M)tsunami
- 1903M8.0
Tonga Islands
4 Jan 1903 · 173 km away
- 1902M7.8
Tonga Islands
9 Feb 1902 · 203 km away
- 1913M7.6
Tonga Islands
26 Jun 1913 · 203 km away
- 1853
Tonga Trench
24 Dec 1853 · 46 km away
tsunami
- 1907
S Of Tonga
1907 · 86 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.