Reviewed by USGSTonga17y ago
M4.5 earthquake 91 km N of Hihifo, Tonga
Wednesday, November 4, 2009, 09:44:29 UTC · 15.137°S, 173.686°W
A magnitude 4.5 earthquake struck 91 km N of Hihifo, Tonga on Wednesday, November 4, 2009, 09:44:29 UTC, at a depth of 133.4 km (intermediate). It is the strongest earthquake within 300 km since an M4.5 on November 3, 2009.
- Magnitude
- 4.5
- Light · mb
- Depth
- 133 km
- Intermediate
- 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
85 tons of TNT
That is about 1/178 of the Hiroshima bomb. A magnitude 5.0 releases about 6 times more energy.
Tectonic setting
50 km
from the nearest mapped plate boundary, between the Tonga and Niuafo'ou plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: intermediate
133 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.1 on November 21, 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 1,357 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.12009 Samoa EarthquakeSeptember 29, 2009 · 175 km E of this epicenter
- 8.0The 1917 Samoa-Tonga EarthquakeJune 26, 1917 · 47 km E of this epicenter
- 7.8146 km ESE of Hihifo, TongaDecember 26, 1975 · 181 km SE of this epicenter
- 7.7133 km NE of Hihifo, TongaSeptember 1, 1981 · 67 km E of this epicenter
- 7.6199 km ESE of Hihifo, TongaApril 2, 1977 · 243 km SE of this epicenter
- 7.488 km NNE of Hihifo, TongaApril 7, 1995 · 18 km E of this epicenter
- 7.2117 km SSW of Hihifo, TongaJanuary 8, 2000 · 208 km S of this epicenter
- 7.219 km ENE of Hihifo, TongaOctober 15, 1984 · 81 km S 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, which together caused about 194 recorded deaths. The most severe:
- 2009M8.1
Samoa Islands
29 Sep 2009 · 175 km away
192 deaths$285 million damagetsunami
- 1917M8.3
Samoa Islands
26 Jun 1917 · 84 km away
2 deathsModerate damage ($1–5M)tsunami
- 1981M7.7
Apia; American Samoa: Pago Pago
1 Sep 1981 · 67 km away · intensity VI
Limited damage (under $1M)tsunami
- 1977M7.6
Apia
2 Apr 1977 · 243 km away · intensity VI
Limited damage (under $1M)tsunami
- 1975M7.8
Samoa Islands
26 Dec 1975 · 181 km away · intensity V
tsunami
- 1957M7.5
Samoa Islands
14 Apr 1957 · 84 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.