Reviewed by USGS5y ago
M5.4 earthquake in Kermadec Islands region
Friday, September 17, 2021, 16:50:42 UTC · 28.201°S, 177.718°W
A magnitude 5.4 earthquake struck in Kermadec Islands region on Friday, September 17, 2021, 16:50:42 UTC, at a depth of 10.0 km (shallow). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M5.4 on September 15, 2021.
- Magnitude
- 5.4
- Moderate · mww
- Depth
- 10 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- III
- Weak (ShakeMap)
- PAGER alert
- Green
- Impact estimate
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 75 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
2 kilotons of TNT
That is about 1/8 of the Hiroshima bomb. It released about 4 times the energy of a magnitude 5.0.
Tectonic setting
78 km
from the nearest mapped plate boundary, between the Kermadec and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
10 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 populated area was estimated to feel noticeable shaking.
After the main event
Aftershocks within 75 km
USGS lists 3 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M4.5 on September 22, 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 2,159 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 · 174 km S of this epicenter
- 8.01976 Kermadec Islands, New Zealand EarthquakeJanuary 14, 1976 · 26 km S of this epicenter
- 7.8south of the Fiji IslandsDecember 9, 2007 · 246 km N of this epicenter
- 7.7Kermadec Islands regionOctober 20, 1986 · 133 km E of this epicenter
- 7.6Kermadec Islands regionJuly 6, 2011 · 200 km SE of this epicenter
- 7.5Kermadec Islands regionFebruary 27, 1955 · 208 km E of this epicenter
- 7.5Kermadec Islands, New ZealandNovember 16, 1917 · 184 km S of this epicenter
- 7.4Kermadec Islands, New ZealandMarch 4, 2021 · 165 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 20 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1986M8.1
Raoul
20 Oct 1986 · 133 km away
Limited damage (under $1M)tsunami
- 1976M7.9
Kermadec Islands
14 Jan 1976 · 113 km away
Limited damage (under $1M)tsunami
- 1968M7.3
S Of, Raoul
25 Jul 1968 · 296 km away
Limited damage (under $1M)tsunami
- 2021M8.1
Sse Of Raoul Island
4 Mar 2021 · 177 km away · intensity IX
tsunami
- 1917M8.0
Kermadec Islands
1 May 1917 · 131 km away
tsunami
- 1955M7.8
Kermadec Islands
27 Feb 1955 · 219 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.