M5.5 earthquake 25 km SSW of Amorgós, Greece

Monday, July 9, 1956, 06:22:49 UTC · 36.622°N, 25.787°E

A magnitude 5.5 earthquake struck 25 km SSW of Amorgós, Greece on Monday, July 9, 1956, 06:22:49 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.7 on July 9, 1956.

Magnitude: 5.5; Moderate · mw
Depth: 15 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: 75 km aftershock search area

In context

How big was it, and why here?

Energy released

2 kilotons of TNT

That is about 1/6 of the Hiroshima bomb. It released about 5 times the energy of a magnitude 5.0.

Tectonic setting

231 km

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

Depth: shallow

15 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 75 km

USGS lists 5 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M5.7 on July 30, 1956. 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 164 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 64 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 29,935 recorded deaths. The most severe:

1883M7.3
Ayvalik, Izmir, Cesme
15 Oct 1883 · 190 km away · intensity X
15,000 deathsExtreme damage ($25M+)
1881M7.3
Khios; Turkey: Cesme
3 Apr 1881 · 186 km away · intensity XI
7,866 deathsExtreme damage ($25M+)tsunami
1810
Crete: Iraklion (Candia)
16 Feb 1810 · 143 km away · intensity X
3,000 deathsSevere damage ($5–24M)tsunami
1750
Morea,Cerigo
7 Jun 1750 · 254 km away · intensity X
2,000 deaths
1856
Crete; Egypt
12 Oct 1856 · 126 km away · intensity XI
600 deathsSevere damage ($5–24M)tsunami
1867M7.0
Mitilini; Turkey: Izmir
7 Mar 1867 · 292 km away
563 deathsSevere damage ($5–24M)tsunami

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

Nearby trackers