M3.9 earthquake 6 km SSW of Politiká, Greece

Sunday, September 20, 1981, 19:54:16 UTC · 38.541°N, 23.514°E

A magnitude 3.9 earthquake struck 6 km SSW of Politiká, Greece on Sunday, September 20, 1981, 19:54:16 UTC, at a depth of 29.2 km (shallow).

Magnitude: 3.9; Minor · mb
Depth: 29 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

11 tons of TNT

That is about 1/1,410 of the Hiroshima bomb. A magnitude 5.0 releases about 45 times more energy.

Tectonic setting

46 km

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

Depth: shallow

29 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 6 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.3 on September 23, 1981. 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 395 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 153 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 28,957 recorded deaths. The most severe:

1883M7.3
Ayvalik, Izmir, Cesme
15 Oct 1883 · 236 km away · intensity X
15,000 deathsExtreme damage ($25M+)
1881M7.3
Khios; Turkey: Cesme
3 Apr 1881 · 241 km away · intensity XI
7,866 deathsExtreme damage ($25M+)tsunami
1750
Morea,Cerigo
7 Jun 1750 · 264 km away · intensity X
2,000 deaths
1867M7.0
Mitilini; Turkey: Izmir
7 Mar 1867 · 260 km away
563 deathsSevere damage ($5–24M)tsunami
1953M7.2
Lixouri-Argostoli (Kephallenia)
12 Aug 1953 · 238 km away · intensity X
476 deaths$100 million damagetsunami
1820M6.9
Zakinthos (Zante)
29 Dec 1820 · 217 km away · intensity X
388 deathsSevere damage ($5–24M)tsunami

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

Nearby trackers