Reviewed by USGSTonga63y ago
M6.5 earthquake 221 km SSW of ‘Ohonua, Tonga
Thursday, July 9, 1964, 11:22:05 UTC · 23.281°S, 175.478°W
A magnitude 6.5 earthquake struck 221 km SSW of ‘Ohonua, Tonga on Thursday, July 9, 1964, 11:22:05 UTC, at a depth of 28.4 km (shallow). It is the strongest earthquake within 300 km since an M7.6 on December 18, 1963.
- Magnitude
- 6.5
- Strong · mw
- Depth
- 28 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
85 kilotons of TNT
That is about 6 times the Hiroshima bomb. It released about 178 times the energy of a magnitude 5.0.
Tectonic setting
59 km
from the nearest mapped plate boundary, between the Kermadec and Tonga plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
28 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 has not published any M2.5+ earthquake within 100 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 77 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.6south of the Fiji IslandsDecember 18, 1963 · 214 km SW of this epicenter
- 7.5110 km E of ‘Ohonua, TongaSeptember 8, 1948 · 281 km NE of this epicenter
- 7.4south of TongaMarch 18, 1905 · 243 km SE of this epicenter
- 7.2south of the Fiji IslandsNovember 24, 1960 · 174 km SW of this epicenter
- 6.7south of the Fiji IslandsSeptember 8, 1920 · 155 km SW of this epicenter
- 6.6south of the Fiji IslandsNovember 23, 1960 · 165 km SW of this epicenter
- 6.5176 km SE of ‘Ohonua, TongaOctober 24, 1943 · 182 km NE of this epicenter
- 6.5TongaDecember 18, 1906 · 237 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 5 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1937M8.1
Fiji Islands
16 Apr 1937 · 252 km away
- 1948M7.9
Tonga Islands
8 Sep 1948 · 296 km away
tsunami
- 1963M7.5
Tonga Trench
18 Dec 1963 · 204 km away
tsunami
- 1853
Tonga Trench
24 Dec 1853 · 237 km away
tsunami
- 1907
S Of Tonga
1907 · 236 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.