Reviewed by USGSTonga17y ago
M4.4 earthquake 265 km SSW of ‘Ohonua, Tonga
Saturday, April 11, 2009, 10:21:42 UTC · 23.525°S, 176.006°W
A magnitude 4.4 earthquake struck 265 km SSW of ‘Ohonua, Tonga on Saturday, April 11, 2009, 10:21:42 UTC, at a depth of 60.4 km (shallow).
- Magnitude
- 4.4
- Light · mb
- Depth
- 60 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
60 tons of TNT
That is about 1/251 of the Hiroshima bomb. A magnitude 5.0 releases about 8 times more energy.
Tectonic setting
41 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
60 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 M4.4 on May 4, 2009. 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 1,049 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 · 177 km SE of this epicenter
- 7.8192 km WSW of Haveluloto, TongaOctober 14, 1997 · 177 km NW of this epicenter
- 7.6south of the Fiji IslandsDecember 18, 1963 · 160 km SW of this epicenter
- 7.6191 km S of ‘Ohonua, TongaMarch 19, 2009 · 148 km E of this epicenter
- 7.4south of TongaMarch 18, 1905 · 281 km E of this epicenter
- 7.3south of the Fiji IslandsJanuary 20, 1970 · 292 km SW of this epicenter
- 7.2south of the Fiji IslandsNovember 24, 1960 · 131 km S of this epicenter
- 7.2south of TongaOctober 10, 1977 · 266 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 11 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 1 recorded deaths. The most severe:
- 1977M7.2
Tonga Trench
22 Jun 1977 · 73 km away · intensity IV
1 death$1 million damagetsunami
- 1937M8.1
Fiji Islands
16 Apr 1937 · 247 km away
- 1975M7.8
S Of Tonga
11 Oct 1975 · 177 km away
- 1982M7.7
Tonga Trench
19 Dec 1982 · 69 km away
tsunami
- 1997M7.7
Tonga Islands
14 Oct 1997 · 177 km away
tsunami
- 2009M7.6
Tonga Islands
19 Mar 2009 · 148 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.