Reviewed by USGS4y ago
M5.1 earthquake in Kermadec Islands region
Sunday, October 31, 2021, 09:18:14 UTC · 28.185°S, 177.347°W
A magnitude 5.1 earthquake struck in Kermadec Islands region on Sunday, October 31, 2021, 09:18:14 UTC, at a depth of 56.1 km (shallow). It is the strongest earthquake within 300 km since an M5.5 on October 29, 2021.
- Magnitude
- 5.1
- Moderate · mb
- Depth
- 56 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: 75 km aftershock search area
In context
How big was it, and why here?
Energy released
674 tons of TNT
That is about 1/22 of the Hiroshima bomb. It released about 1 times the energy of a magnitude 5.0.
Tectonic setting
112 km
from the nearest mapped plate boundary, between the Kermadec and Australian plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
56 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 75 km
USGS lists 1 M2.5+ earthquake within 75 km in the following 30 days; the largest was M4.3 on November 30, 2021. 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 2,143 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.12021 Kermadec Islands, New Zealand EarthquakeMarch 4, 2021 · 171 km S of this epicenter
- 8.01976 Kermadec Islands, New Zealand EarthquakeJanuary 14, 1976 · 41 km SW of this epicenter
- 7.8south of the Fiji IslandsDecember 9, 2007 · 244 km N of this epicenter
- 7.7Kermadec Islands regionOctober 20, 1986 · 96 km E of this epicenter
- 7.6Kermadec Islands regionJuly 6, 2011 · 180 km SE of this epicenter
- 7.5Kermadec Islands regionFebruary 27, 1955 · 172 km E of this epicenter
- 7.5Kermadec Islands, New ZealandNovember 16, 1917 · 191 km S of this epicenter
- 7.4Kermadec Islands, New ZealandMarch 4, 2021 · 173 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 19 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1986M8.1
Raoul
20 Oct 1986 · 96 km away
Limited damage (under $1M)tsunami
- 1976M7.9
Kermadec Islands
14 Jan 1976 · 112 km away
Limited damage (under $1M)tsunami
- 2021M8.1
Sse Of Raoul Island
4 Mar 2021 · 173 km away · intensity IX
tsunami
- 1917M8.0
Kermadec Islands
1 May 1917 · 118 km away
tsunami
- 1955M7.8
Kermadec Islands
27 Feb 1955 · 182 km away
- 1976M7.8
Kermadec Islands
14 Jan 1976 · 194 km away · intensity VIII
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.