M3.1 earthquake 4 km SW of Vrachnaíika, Greece

Monday, September 20, 2004, 05:03:04 UTC · 38.130°N, 21.630°E

A magnitude 3.1 earthquake struck 4 km SW of Vrachnaíika, Greece on Monday, September 20, 2004, 05:03:04 UTC, at a depth of 27.0 km (shallow).

Magnitude: 3.1; Minor · md
Depth: 27 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

674 kg of TNT

That is about 1/22,353 of the Hiroshima bomb. A magnitude 5.0 releases about 708 times more energy.

Tectonic setting

31 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

27 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 8 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.3 on October 17, 2004. 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 508 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 160 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 5,835 recorded deaths. The most severe:

1750
Morea,Cerigo
7 Jun 1750 · 247 km away · intensity X
2,000 deaths
1953M7.2
Lixouri-Argostoli (Kephallenia)
12 Aug 1953 · 75 km away · intensity X
476 deaths$100 million damagetsunami
1820M6.9
Zakinthos (Zante)
29 Dec 1820 · 54 km away · intensity X
388 deathsSevere damage ($5–24M)tsunami
1886M6.8
Triphylie (Peleponese), Philiatra
27 Aug 1886 · 115 km away · intensity X
326 deathsSevere damage ($5–24M)tsunami
1767M6.7
Kefalonia
11 Jul 1767 · 103 km away · intensity X
303 deathsSevere damage ($5–24M)
1894M6.7
Locride, Malesina-Martinon (Lokris)
20 Apr 1894 · 147 km away · intensity X
255 deathsSevere damage ($5–24M)

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

Nearby trackers