Reviewed by USGSTonga79y ago
M7.5 earthquake 110 km E of ‘Ohonua, Tonga
Wednesday, September 8, 1948, 15:09:14 UTC · 21.222°S, 173.891°W
A magnitude 7.5 earthquake struck 110 km E of ‘Ohonua, Tonga on Wednesday, September 8, 1948, 15:09:14 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.8 on June 26, 1913.
- Magnitude
- 7.5
- Major · mw
- Depth
- 15 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- V
- Moderate (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
2.7 megatons of TNT
That is about 178 times the Hiroshima bomb. It released about 5,623 times the energy of a magnitude 5.0.
Tectonic setting
20 km
from the nearest mapped plate boundary, between the Tonga and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
15 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 200 km
USGS has not published any M2.5+ earthquake within 200 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 45 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.0TongaJanuary 4, 1903 · 178 km NW of this epicenter
- 7.8111 km SSE of Pangai, TongaJune 26, 1913 · 61 km N of this epicenter
- 7.4103 km ESE of Neiafu, TongaFebruary 27, 1921 · 273 km N of this epicenter
- 7.385 km ESE of Neiafu, TongaJanuary 2, 1907 · 247 km N of this epicenter
- 7.2108 km SE of Neiafu, TongaDecember 19, 1906 · 235 km N of this epicenter
- 7.0122 km ESE of Pangai, TongaNovember 12, 1946 · 132 km NE of this epicenter
- 6.915 km WSW of Pangai, TongaFebruary 27, 1905 · 163 km NW 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. The most severe:
- 1865M8.0
Tonga Islands
18 Nov 1865 · 196 km away
Limited damage (under $1M)tsunami
- 1903M8.0
Tonga Islands
4 Jan 1903 · 178 km away
- 1948M7.9
Tonga Islands
8 Sep 1948 · 27 km away
tsunami
- 1902M7.8
Tonga Islands
9 Feb 1902 · 136 km away
- 1913M7.6
Tonga Islands
26 Jun 1913 · 136 km away
- 1853
Tonga Trench
24 Dec 1853 · 132 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.