M6.5 earthquake 3 km SW of Prato, Italy

Thursday, May 6, 1976, 20:00:11 UTC · 46.356°N, 13.275°E

A magnitude 6.5 earthquake struck 3 km SW of Prato, Italy on Thursday, May 6, 1976, 20:00:11 UTC, at a depth of 9.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.

Magnitude: 6.5; Strong · ms
Depth: 9 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: IX; Violent (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

85 kilotons of TNT

That is about 6 times the Hiroshima bomb. It released about 178 times the energy of a magnitude 5.0.

Tectonic setting

663 km

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

Depth: shallow

9 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 100 km

USGS lists 56 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M5.9 on May 7, 1976. 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 66 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 53 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 1,204 recorded deaths. The most severe:

1976M6.5
Ne, Balkans Nw: Slovenia: Nw
6 May 1976 · 0 km away · intensity X
978 deaths$3.6 billion damage
1768
Santa Sofia
19 Oct 1768 · 280 km away · intensity X
120 deathsSevere damage ($5–24M)
1873
Bellunese
29 Jun 1873 · 69 km away · intensity X
55 deathsModerate damage ($1–5M)
1930M6.0
Senigallia
30 Oct 1930 · 275 km away · intensity IX
18 deathsSevere damage ($5–24M)tsunami
1976M6.0
Northeastern
15 Sep 1976 · 8 km away · intensity IX
11 deathsModerate damage ($1–5M)
1895M6.1
Slovenia: Ljubljana
14 Apr 1895 · 98 km away · intensity IX
7 deathsSevere damage ($5–24M)

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

Nearby trackers