Reviewed by USGSItaly97y ago
M6.6 earthquake 3 km SSW of Bisaccia Nuova, Italy
Wednesday, July 23, 1930, 00:08:41 UTC · 40.980°N, 15.341°E
A magnitude 6.6 earthquake struck 3 km SSW of Bisaccia Nuova, Italy on Wednesday, July 23, 1930, 00:08:41 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M6.7 on January 13, 1915.
- Magnitude
- 6.6
- Strong · mw
- Depth
- 15 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VII
- Very strong (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
138 kilotons of TNT
That is about 9 times the Hiroshima bomb. It released about 288 times the energy of a magnitude 5.0.
Tectonic setting
254 km
from the nearest mapped plate boundary, between the Eurasian and African 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 100 km
USGS lists 1 M2.5+ earthquake within 100 km in the following 30 days; the largest was M5.2 on July 23, 1930. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 22 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.25 km W of San Nicolò, ItalySeptember 8, 1905 · 263 km S of this epicenter
- 6.74 km WNW of San Benedetto dei Marsi, ItalyJanuary 13, 1915 · 187 km NW of this epicenter
- 6.572 km WSW of Cittadella del Capo, ItalyAugust 1, 1910 · 182 km S of this epicenter
- 6.025 km W of San Marco, ItalyJuly 7, 1915 · 98 km SW of this epicenter
- 5.91 km ENE of Cairano, ItalyJune 7, 1910 · 10 km SE of this epicenter
- 5.86 km NNW of Tropea, ItalyMarch 7, 1928 · 255 km S of this epicenter
- 5.89 km ESE of Marina di Camerota, ItalyApril 5, 1911 · 114 km S of this epicenter
- 5.718 km SSE of Anzio, ItalyOctober 22, 1919 · 226 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 68 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 119,087 recorded deaths. The most severe:
- 1703
Central Apennino, Norcia, L'Aquila, Perugia
14 Jan 1703 · 273 km away · intensity XI
40,000 deathsExtreme damage ($25M+)
- 1915M7.5
Marsica, Avezzano, Abruzzi
13 Jan 1915 · 191 km away · intensity XI
29,978 deaths$60 million damage
- 1857M6.5
Campania, Potenza
16 Dec 1857 · 94 km away · intensity X
10,000 deathsExtreme damage ($25M+)
- 1703M6.7
L'Aquila (Aquila)
2 Feb 1703 · 243 km away · intensity XI
10,000 deathsSevere damage ($5–24M)tsunami
- 1857
Calabria,Montemurro
16 Sep 1857 · 197 km away
10,000 deathsSevere damage ($5–24M)
- 1805
Molise, Rosolone, Napoli (Naples), Isernia
26 Jul 1805 · 59 km away · intensity XI
5,600 deathsExtreme damage ($25M+)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.