Reviewed by USGS7y ago
M4.5 earthquake in Kermadec Islands region
Wednesday, August 21, 2019, 13:34:55 UTC · 31.233°S, 177.946°W
A magnitude 4.5 earthquake struck in Kermadec Islands region on Wednesday, August 21, 2019, 13:34:55 UTC, at a depth of 31.5 km (shallow). It is the strongest earthquake within 300 km since an M4.5 on August 21, 2019.
- Magnitude
- 4.5
- Light · mb
- Depth
- 32 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
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
82 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
32 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 M5.0 on September 6, 2019. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 4.8Kermadec Islands region7y ago · 31 km E of this epicenter
- 5.0Kermadec Islands region7y ago · 24 km NE of this epicenter
- 4.5Kermadec Islands region7y ago · 31 km W of this epicenter
- 4.6Kermadec Islands region7y ago · 9 km SE of this epicenter
- 4.7Kermadec Islands, New Zealand7y ago · 44 km NE of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 2,214 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 · 123 km E of this epicenter
- 7.6Kermadec Islands regionJuly 6, 2011 · 243 km NE of this epicenter
- 7.5Kermadec Islands, New ZealandNovember 16, 1917 · 154 km N of this epicenter
- 7.4Kermadec Islands regionOctober 21, 2011 · 298 km NE of this epicenter
- 7.4Kermadec Islands regionMay 16, 2006 · 144 km SW of this epicenter
- 7.3Kermadec Islands regionSeptember 14, 1959 · 275 km N of this epicenter
- 7.3Kermadec Islands, New ZealandMarch 26, 1963 · 140 km N of this epicenter
- 7.3Kermadec Islands, New ZealandJuly 25, 1968 · 52 km N 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:
- 1976M7.9
Kermadec Islands
14 Jan 1976 · 232 km away
Limited damage (under $1M)tsunami
- 1968M7.3
S Of, Raoul
25 Jul 1968 · 65 km away
Limited damage (under $1M)tsunami
- 1917M8.0
Kermadec Islands
1 May 1917 · 244 km away
tsunami
- 1976M7.8
Kermadec Islands
14 Jan 1976 · 161 km away · intensity VIII
- 1978M7.7
S Of
9 Feb 1978 · 83 km away
- 1943M7.6
S Of
14 Sep 1943 · 164 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.