Reviewed by USGSTonga20y ago
M4.9 earthquake 33 km W of Pangai, Tonga
Monday, July 17, 2006, 04:11:34 UTC · 19.757°S, 174.667°W
A magnitude 4.9 earthquake struck 33 km W of Pangai, Tonga on Monday, July 17, 2006, 04:11:34 UTC, at a depth of 25.0 km (shallow). It is the strongest earthquake within 300 km since an M5.0 on July 16, 2006.
- Magnitude
- 4.9
- Light · mb
- Depth
- 25 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
57 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: shallow
25 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 August 13, 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 1,262 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 · 283 km NE of this epicenter
- 8.0TongaJanuary 4, 1903 · 44 km SW of this epicenter
- 8.02006 Tonga EarthquakeMay 3, 2006 · 74 km SE of this epicenter
- 7.8159 km W of Pangai, TongaDecember 14, 1950 · 126 km W of this epicenter
- 7.8111 km SSE of Pangai, TongaJune 26, 1913 · 136 km SE of this epicenter
- 7.5110 km E of ‘Ohonua, TongaSeptember 8, 1948 · 182 km SE of this epicenter
- 7.5262 km WNW of Haveluloto, TongaMay 21, 1962 · 294 km W of this epicenter
- 7.4103 km ESE of Neiafu, TongaFebruary 27, 1921 · 196 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 12 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1919M8.1
Tonga Islands
30 Apr 1919 · 275 km away
Limited damage (under $1M)tsunami
- 1865M8.0
Tonga Islands
18 Nov 1865 · 126 km away
Limited damage (under $1M)tsunami
- 2006M7.9
Tonga Islands
3 May 2006 · 74 km away · intensity VII
Limited damage (under $1M)tsunami
- 1903M8.0
Tonga Islands
4 Jan 1903 · 44 km away
- 1948M7.9
Tonga Islands
8 Sep 1948 · 155 km away
tsunami
- 1902M7.8
Tonga Islands
9 Feb 1902 · 75 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.