M6.9 earthquake in Kermadec Islands region

Monday, September 10, 2018, 04:19:02 UTC · 31.745°S, 179.373°W

A magnitude 6.9 earthquake struck in Kermadec Islands region on Monday, September 10, 2018, 04:19:02 UTC, at a depth of 115.0 km (intermediate). USGS received 9 “Did You Feel It?” reports, with a maximum reported intensity of III (weak). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M6.9 on June 23, 2014.

Magnitude: 6.9; Strong · mww
Depth: 115 km; Intermediate
Felt reports: 9; Max intensity III
Est. shaking: IV; Light (ShakeMap)
PAGER alert: Green; Impact estimate
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 100 km aftershock search area

In context

How big was it, and why here?

Energy released

338 kilotons of TNT

That is about 22 times the Hiroshima bomb. It released about 708 times the energy of a magnitude 5.0.

Tectonic setting

31 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

115 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

Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.

Place	Intensity	Reports	Distance
Napier, Hawkeʿs Bay, New Zealand	III · Weak	2	930 km
Tauranga, Bay of Plenty, New Zealand	III · Weak	1	786 km
Te Horo, Wellington, New Zealand	III · Weak	1	1126 km
Wellington, Wellington, New Zealand	II · Weak	1	1186 km
Christchurch, Canterbury, New Zealand	II · Weak	1	1490 km
Tapanui, Otago, New Zealand	II · Weak	1	1861 km
Kapiti, Wellington, New Zealand	II · Weak	1	1140 km
Auckland, Auckland, New Zealand	I · Not felt	1	791 km

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 100 km

USGS lists 12 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M4.9 on September 10, 2018. 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 1,818 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 6 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

1968M7.3
S Of, Raoul
25 Jul 1968 · 140 km away
Limited damage (under $1M)tsunami
1976M7.8
Kermadec Islands
14 Jan 1976 · 288 km away · intensity VIII
1978M7.7
S Of
9 Feb 1978 · 225 km away
1943M7.6
S Of
14 Sep 1943 · 298 km away
2014M6.9
Sse Of Raoul Island
23 Jun 2014 · 252 km away
tsunami
2013M6.5
S Of, Raoul
30 Sep 2013 · 135 km away
tsunami

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

Nearby trackers