Reviewed by USGSNew Zealand5y ago
M4.5 earthquake in Kermadec Islands, New Zealand
Wednesday, September 15, 2021, 23:32:35 UTC · 29.973°S, 178.917°W
A magnitude 4.5 earthquake struck in Kermadec Islands, New Zealand on Wednesday, September 15, 2021, 23:32:35 UTC, at a depth of 185.0 km (intermediate). It is the strongest earthquake within 300 km since an M5.4 on September 15, 2021.
- Magnitude
- 4.5
- Light · mb
- Depth
- 185 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 earthquake
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
19 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: intermediate
185 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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 2,275 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.21917 Kermadec Islands, New Zealand EarthquakeMay 1, 1917 · 256 km SE of this epicenter
- 8.12021 Kermadec Islands, New Zealand EarthquakeMarch 4, 2021 · 160 km E of this epicenter
- 8.01976 Kermadec Islands, New Zealand EarthquakeJanuary 14, 1976 · 211 km NE of this epicenter
- 7.6Kermadec Islands regionJuly 6, 2011 · 253 km E of this epicenter
- 7.5Kermadec Islands, New ZealandNovember 16, 1917 · 105 km E of this epicenter
- 7.4Kermadec Islands, New ZealandMarch 4, 2021 · 109 km E of this epicenter
- 7.4Kermadec Islands regionOctober 21, 2011 · 281 km E of this epicenter
- 7.4Kermadec Islands regionMay 16, 2006 · 208 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 16 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1976M7.9
Kermadec Islands
14 Jan 1976 · 167 km away
Limited damage (under $1M)tsunami
- 1968M7.3
S Of, Raoul
25 Jul 1968 · 104 km away
Limited damage (under $1M)tsunami
- 2021M8.1
Sse Of Raoul Island
4 Mar 2021 · 161 km away · intensity IX
tsunami
- 1917M8.0
Kermadec Islands
1 May 1917 · 204 km away
tsunami
- 1976M7.8
Kermadec Islands
14 Jan 1976 · 163 km away · intensity VIII
- 1959M7.7
Kermadec Islands
14 Sep 1959 · 248 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.