M4.7 earthquake 78 km SSE of Kieta, Papua New Guinea

Saturday, July 21, 2007, 14:27:54 UTC · 6.807°S, 156.024°E

A magnitude 4.7 earthquake struck 78 km SSE of Kieta, Papua New Guinea on Saturday, July 21, 2007, 14:27:54 UTC, at a depth of 122.9 km (intermediate). It is the strongest earthquake within 300 km since an M5.0 on July 18, 2007.

Magnitude: 4.7; Light · mb
Depth: 123 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 earthquakeDashed circle: 50 km aftershock search area

In context

How big was it, and why here?

Energy released

169 tons of TNT

That is about 1/89 of the Hiroshima bomb. A magnitude 5.0 releases about 3 times more energy.

Tectonic setting

98 km

from the nearest mapped plate boundary, between the Pacific and Woodlark plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: intermediate

123 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 lists 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.5 on July 29, 2007. 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 1,159 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 14 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 61 recorded deaths. The most severe:

2007M8.1
Solomon Islands
1 Apr 2007 · 216 km away
52 deathsSevere damage ($5–24M)tsunami
1939M7.7
Bougainville Island
30 Jan 1939 · 77 km away
5 deathsModerate damage ($1–5M)tsunami
1971M7.9
New Ireland: Bougainville
14 Jul 1971 · 276 km away · intensity IX
3 deathsUnder $1 million damagetsunami
1996M7.2
Bougainville Island
29 Apr 1996 · 118 km away
1 deathModerate damage ($1–5M)
1975M7.9
Bismarck Sea: Bougainville
20 Jul 1975 · 110 km away · intensity VIII
Severe damage ($5–24M)tsunami
1959M7.3
Solomon Islands
17 Aug 1959 · 77 km away
Severe damage ($5–24M)tsunami

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

Nearby trackers