Reviewed by USGSTonga20y ago
M4.5 earthquake 138 km WNW of Neiafu, Tonga
Monday, July 17, 2006, 20:42:19 UTC · 18.029°S, 175.118°W
A magnitude 4.5 earthquake struck 138 km WNW of Neiafu, Tonga on Monday, July 17, 2006, 20:42:19 UTC, at a depth of 267.7 km (intermediate). It is the strongest earthquake within 300 km since an M4.9 on July 17, 2006.
- Magnitude
- 4.5
- Light · mb
- Depth
- 268 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
44 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
268 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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.5 on August 6, 2006. 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 1,230 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11919 Tonga EarthquakeApril 30, 1919 · 285 km E of this epicenter
- 8.0TongaJanuary 4, 1903 · 220 km S of this epicenter
- 8.02006 Tonga EarthquakeMay 3, 2006 · 262 km SE of this epicenter
- 7.8159 km W of Pangai, TongaDecember 14, 1950 · 203 km SW of this epicenter
- 7.4103 km ESE of Neiafu, TongaFebruary 27, 1921 · 240 km SE of this epicenter
- 7.385 km ESE of Neiafu, TongaJanuary 2, 1907 · 223 km SE of this epicenter
- 7.2108 km SE of Neiafu, TongaDecember 19, 1906 · 246 km SE of this epicenter
- 7.2Fiji regionMarch 31, 1907 · 194 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 9 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1919M8.1
Tonga Islands
30 Apr 1919 · 277 km away
Limited damage (under $1M)tsunami
- 1865M8.0
Tonga Islands
18 Nov 1865 · 236 km away
Limited damage (under $1M)tsunami
- 2006M7.9
Tonga Islands
3 May 2006 · 262 km away · intensity VII
Limited damage (under $1M)tsunami
- 1903M8.0
Tonga Islands
4 Jan 1903 · 220 km away
- 1902M7.8
Tonga Islands
9 Feb 1902 · 249 km away
- 1950M7.7
Tonga Islands
14 Dec 1950 · 188 km away · intensity VI
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.