Reviewed by USGS49y ago
M4.9 earthquake south of Tonga
Monday, November 14, 1977, 13:28:55 UTC · 25.423°S, 174.777°W
A magnitude 4.9 earthquake struck south of Tonga on Monday, November 14, 1977, 13:28:55 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M5.0 on November 1, 1977.
- Magnitude
- 4.9
- Light · mb
- Depth
- 33 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: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
338 tons of TNT
That is about 1/45 of the Hiroshima bomb. A magnitude 5.0 releases about 1 times more energy.
Tectonic setting
52 km
from the nearest mapped plate boundary, between the Kermadec and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
33 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 50 km
USGS lists 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.8 on November 14, 1977. 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 166 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8south of TongaOctober 11, 1975 · 68 km NW of this epicenter
- 7.6south of the Fiji IslandsDecember 18, 1963 · 221 km W of this epicenter
- 7.4south of TongaMarch 18, 1905 · 182 km NE of this epicenter
- 7.3south of the Fiji IslandsJanuary 20, 1970 · 251 km W of this epicenter
- 7.2south of the Fiji IslandsNovember 24, 1960 · 170 km NW of this epicenter
- 7.2south of TongaOctober 10, 1977 · 79 km SW of this epicenter
- 7.0south of TongaJanuary 10, 1956 · 121 km S of this epicenter
- 6.8south of TongaApril 19, 1905 · 188 km SE 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:
- 1955M7.8
Kermadec Islands
27 Feb 1955 · 295 km away
- 1975M7.8
S Of Tonga
11 Oct 1975 · 68 km away
- 1905M7.5
Kermadec Islands
18 Mar 1905 · 291 km away
- 1963M7.5
Tonga Trench
18 Dec 1963 · 196 km away
tsunami
- 1977M7.2
Tonga Trench
10 Oct 1977 · 79 km away
tsunami
- 1956M7.0
Tonga Islands
10 Jan 1956 · 79 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.