M5.6 earthquake in Kermadec Islands, New Zealand

Monday, August 2, 2021, 01:27:40 UTC · 30.459°S, 177.805°W

A magnitude 5.6 earthquake struck in Kermadec Islands, New Zealand on Monday, August 2, 2021, 01:27:40 UTC, at a depth of 31.6 km (shallow). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M5.6 on July 25, 2021.

Magnitude: 5.6; Moderate · mww
Depth: 32 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

4 kilotons of TNT

That is about 1/4 of the Hiroshima bomb. It released about 8 times the energy of a magnitude 5.0.

Tectonic setting

105 km

from the nearest mapped plate boundary, between the Kermadec and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

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 populated area was estimated to feel noticeable shaking.

After the main event

Aftershocks within 75 km

USGS lists 15 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M6.4 on August 31, 2021. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 2,518 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 17 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

1986M8.1
Raoul
20 Oct 1986 · 295 km away
Limited damage (under $1M)tsunami
1976M7.9
Kermadec Islands
14 Jan 1976 · 145 km away
Limited damage (under $1M)tsunami
1968M7.3
S Of, Raoul
25 Jul 1968 · 68 km away
Limited damage (under $1M)tsunami
2021M8.1
Sse Of Raoul Island
4 Mar 2021 · 95 km away · intensity IX
tsunami
1917M8.0
Kermadec Islands
1 May 1917 · 160 km away
tsunami
1976M7.8
Kermadec Islands
14 Jan 1976 · 82 km away · intensity VIII

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers