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Note:This page contains AI-generated content for informational and entertainment purposes only. It may contain inaccuracies. Raw event data is from USGS and EMSC. All statistics, lists, and derived information are generated by this site. Full disclaimerFound an error?
Location:
CENTRAL ITALY
Period:
25 Jun 2009 01:48:03 - 28 Jun 2009 09:26:30 (3 days 7 hours 38 minutes)
Volcanoes in 100km radius:
Colli Albani(99km)
Earthquakes:
118
16 swarms found nearby.
2007
S20070208.1(27.2km)
8 Feb
1 day 3 hours
26 earthquakes
2009
S20090330.1(26.8km)
30 Mar
98 days 16 hours
6163 earthquakes
S20090510.1(10.0km)
9 May
13 days 16 hours
178 earthquakes
12 Jul
6 days 5 hours
128 earthquakes
S20090801.1(17.9km)
31 Jul
19 days 15 hours
224 earthquakes
22 Aug
6 days 9 hours
83 earthquakes
2010
30 Aug
25 days 22 hours
427 earthquakes
30 Sep
11 days 3 hours
111 earthquakes
S20101020.1(11.2km)
19 Oct
6 days 18 hours
375 earthquakes
3 Nov
6 days 0 hours
176 earthquakes
2011
S20110215.1(21.5km)
15 Feb
1 day 8 hours
27 earthquakes
5 Mar
8 days 1 hours
87 earthquakes
S20111019.2(10.4km)
18 Oct
1 day 4 hours
25 earthquakes
2016
S20160824.1(27.5km)
24 Aug
15 days 11 hours
415 earthquakes
S20161030.1(14.3km)
30 Oct
3 days 20 hours
72 earthquakes
2017
18 Jan
5 days 9 hours
231 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20090626.1: Analysis of Central Italy Activity in June 2009

Central Italy experienced a notable seismic swarm designated S20090626.1 between 25 and 28 June 2009. The sequence began at 01:48 UTC on 25 June and concluded at 09:26 UTC on 28 June, spanning 79 hours and 38 minutes. During this period, 118 earthquakes were recorded, providing valuable data on regional seismicity patterns.

Analysis of the first 100 events reveals a concentration of low-to-moderate magnitude activity. Magnitudes ranged from 1.4 to 4.1, with the largest event occurring at 21:00 UTC on 25 June at a shallow depth of 2 km. Most events clustered around magnitude 1.6–2.2, while several reached 3.0 or above, including a 3.7 at 2 km depth on 26 June and a 3.3 at 10 km on 28 June. Depths predominantly varied between 8 and 12 km, though some shallower occurrences (2–5 km) coincided with higher magnitudes. Timing showed initial bursts on 25 June followed by sustained activity through 27 June and into the early hours of 28 June.

This swarm unfolded in the broader tectonic setting of the Apennine chain, where extensional faulting dominates due to the ongoing convergence between the African and Eurasian plates. The region features a network of normal faults oriented northwest-southeast, accommodating crustal stretching at rates of several millimeters per year. Shallow crustal earthquakes are common, reflecting brittle failure in the upper 10–15 km of the lithosphere.

Seismic history in central Italy includes destructive events tied to these active structures. The 1997 Umbria-Marche sequence and the 2009 L’Aquila mainshock illustrate the area’s potential for both isolated large quakes and prolonged swarm-like episodes. Instrumental records since 2000 document three swarms in total, with one occurring in 2007 and two in 2009.

The June 2009 swarm adds to understanding of how clustered microseismicity can occur along the same fault systems responsible for larger events. Event depths and magnitude distributions align with typical Apennine behavior, where fluid migration or stress transfer may trigger successive ruptures without a single dominant mainshock.

References

  • Istituto Nazionale di Geofisica e Vulcanologia (INGV) seismic bulletins
  • United States Geological Survey (USGS) earthquake catalog
  • Journal of Geophysical Research: Solid Earth publications on Apennine tectonics