Reviewed by USGS15y ago
M4.6 earthquake in Kermadec Islands region
Saturday, October 22, 2011, 11:03:34 UTC · 28.840°S, 176.163°W
A magnitude 4.6 earthquake struck in Kermadec Islands region on Saturday, October 22, 2011, 11:03:34 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M5.2 on October 22, 2011.
- Magnitude
- 4.6
- Light · mb
- Depth
- 35 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
120 tons of TNT
That is about 1/126 of the Hiroshima bomb. A magnitude 5.0 releases about 4 times more energy.
Tectonic setting
13 km
from the nearest mapped plate boundary, between the Kermadec and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
35 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 5 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.3 on October 28, 2011. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 4.3Kermadec Islands region15y ago · 35 km SE of this epicenter
- 4.2Kermadec Islands region15y ago · 7 km NW of this epicenter
- 4.1Kermadec Islands region15y ago · 39 km N of this epicenter
- 5.3Kermadec Islands region15y ago · 8 km NE of this epicenter
- 4.6Kermadec Islands region15y ago · 25 km SE of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 1,552 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 · 266 km S of this epicenter
- 8.01976 Kermadec Islands, New Zealand EarthquakeJanuary 14, 1976 · 153 km W of this epicenter
- 7.7Kermadec Islands regionOctober 20, 1986 · 83 km N of this epicenter
- 7.6Kermadec Islands regionJuly 6, 2011 · 80 km S of this epicenter
- 7.5Kermadec Islands regionFebruary 27, 1955 · 79 km NE of this epicenter
- 7.5Kermadec Islands, New ZealandNovember 16, 1917 · 197 km SW of this epicenter
- 7.4Kermadec Islands regionOctober 21, 2011 · 19 km SW of this epicenter
- 7.3Kermadec Islands regionSeptember 14, 1959 · 102 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1986M8.1
Raoul
20 Oct 1986 · 83 km away
Limited damage (under $1M)tsunami
- 1976M7.9
Kermadec Islands
14 Jan 1976 · 130 km away
Limited damage (under $1M)tsunami
- 1917M8.0
Kermadec Islands
1 May 1917 · 91 km away
tsunami
- 1955M7.8
Kermadec Islands
27 Feb 1955 · 114 km away
- 1976M7.8
Kermadec Islands
14 Jan 1976 · 158 km away · intensity VIII
- 1959M7.7
Kermadec Islands
14 Sep 1959 · 90 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.