M7.2 earthquake 117 km N of Finschhafen, Papua New Guinea

Monday, December 22, 1997, 02:05:50 UTC · 5.495°S, 147.867°E

A magnitude 7.2 earthquake struck 117 km N of Finschhafen, Papua New Guinea on Monday, December 22, 1997, 02:05:50 UTC, at a depth of 179.3 km (intermediate). It is the strongest earthquake within 300 km since an M7.2 on May 15, 1992.

Magnitude: 7.2; Major · mwc
Depth: 179 km; Intermediate
Felt reports: 0; Did You Feel It?
Est. shaking: VI; Strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

951 kilotons of TNT

That is about 63 times the Hiroshima bomb. It released about 1,995 times the energy of a magnitude 5.0.

Tectonic setting

169 km

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

Depth: intermediate

179 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 200 km

USGS lists 14 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.9 on January 16, 1998. 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 967 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 25 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 155 recorded deaths. The most severe:

1988M4.3
Kaiapit (Landslide Generated)
6 Sep 1988 · 192 km away
74 deathsModerate damage ($1–5M)
1993M6.9
Eastern: Upper Markham Valley
13 Oct 1993 · 209 km away
60 deaths$5 million damage
1970M7.3
Madang
31 Oct 1970 · 273 km away · intensity VIII
18 deaths$2 million damagetsunami
1987M7.6
Huon Peninsula, Umboi Island
8 Feb 1987 · 69 km away · intensity VII
3 deaths$3 million damagetsunami
1906M8.0
New Britain
14 Sep 1906 · 209 km away
Severe damage ($5–24M)tsunami
1857M8.0
Bismarck Sea
17 Apr 1857 · 96 km away
Moderate damage ($1–5M)tsunami

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

Nearby trackers