Reviewed by USGSTonga40y ago
M7.2 earthquake 157 km WSW of Haveluloto, Tonga
Thursday, October 30, 1986, 01:28:54 UTC · 21.702°S, 176.616°W
A magnitude 7.2 earthquake struck 157 km WSW of Haveluloto, Tonga on Thursday, October 30, 1986, 01:28:54 UTC, at a depth of 188.1 km (intermediate). It is the strongest earthquake within 300 km since an M7.2 on December 19, 1982.
- Magnitude
- 7.2
- Major · mw
- Depth
- 188 km
- Intermediate
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- V
- Moderate (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 200 km aftershock search area
In context
How big was it, and why here?
Energy released
951 kilotons of TNT
That is about 63 times the Hiroshima bomb. It released about 1,995 times the energy of a magnitude 5.0.
Tectonic setting
13 km
from the nearest mapped plate boundary, between the Tonga and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: intermediate
188 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 200 km
USGS lists 2 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M4.5 on October 30, 1986. 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 878 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.0TongaJanuary 4, 1903 · 253 km NE of this epicenter
- 7.8159 km W of Pangai, TongaDecember 14, 1950 · 235 km N of this epicenter
- 7.5110 km E of ‘Ohonua, TongaSeptember 8, 1948 · 287 km E of this epicenter
- 7.5262 km WNW of Haveluloto, TongaMay 21, 1962 · 200 km NW of this epicenter
- 7.4Fiji regionSeptember 28, 1957 · 221 km NW of this epicenter
- 7.3227 km WNW of Haveluloto, TongaApril 16, 1937 · 143 km NW of this epicenter
- 7.3Fiji regionMay 25, 1944 · 292 km W of this epicenter
- 7.2Fiji regionOctober 9, 1967 · 272 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, which together caused about 1 recorded deaths. The most severe:
- 1977M7.2
Tonga Trench
22 Jun 1977 · 150 km away · intensity IV
1 death$1 million damagetsunami
- 1937M8.1
Fiji Islands
16 Apr 1937 · 46 km away
- 1903M8.0
Tonga Islands
4 Jan 1903 · 253 km away
- 1948M7.9
Tonga Islands
8 Sep 1948 · 282 km away
tsunami
- 1950M7.7
Tonga Islands
14 Dec 1950 · 253 km away · intensity VI
- 1982M7.7
Tonga Trench
19 Dec 1982 · 281 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.