Archive for May, 2012

May 10, 2012

L’Aquila, Italy 06/04/2009, 6.3Mw and aftershocks

An earthquake of magnitude Mw 6.3 occurred on 06/04/2009 in central Italy, at a depth of 8.3 km, West of L’Aquila (Abruzzo Region) at 01:32:40 UTC (03:32:40 local time).

At least 295 people killed, 1,000 injured, 55,000 homeless, 15,000 buildings damaged or destroyed and landslides in the L’Aquila area.
Felt (VII) at L’Aquila; (VI) at Corfinio and San Demetrio ne’ Vestini; (V) at Avezzano, Chieti, Pescara, Rieti, San Benedetto del Tronto, Sulmona and Teramo; (IV) at Amelia, Ancona, Ascoli Piceno, Castelfrentano, Fiumicino, Fondi, Francavilla al Mare, Frosinone, Guidonia, Isernia, Lanciano, Latina, Macerata, Montesilvano, Naples, Osimo, Pesaro, Rome and Terni. Felt throughout central Italy and as far north as Florence, Milan and Venice and as far south as Bari and Salerno. Also felt at Vienna, Austria; Tirana, Albania; Knin, Croatia; Nuremberg, Germany; San Gwann, Malta; Celje, Slovenia; Zurich, Switzerland and Podgorica, Montenegro [usgs].

According to different authors, the total rupture length associated with the L’Aquila earthquake was estimated in the range of about 3 to 19 km The zone of surface fractures along the NW-SE striking Paganica fault
stretched continuously for the length of 2.6 km, with observed vertical offsets and opening of up to several centimeters.
The L’Aquila event was caused by a normal fault. The epicenter was about 10 km west of the surface rupture, and the ground subsidence and seismic shaking were dominant mostly in between the epicenter and the surface rupture, and also coincided more or less with the morphology of the Aterno Valley.

The data below is located with the stations of the INGV National Seismic Network
Lat: 42.342 Long: 13.38
Magnitude: 6.3Mw (5.9 ML)
Depth: 8.3 km
Location: Via della Pineta, 67100 L’Aquila, Province of L’Aquila
Catalog Source: BOLLSI-INGVOther Networks estimates of the event
Network, Mag, When, Lat, Long, Depth
GEOFON= 6.2Mw, 06/04/2009 1:32:42.2, 42.4, 13.3, 10
USGS= 6.3Mw, 6.2MS, 5.9mb, 5.5ML, 06/04/2009 1:32:39.0, 42.334, 13.334, 8.8
RASGS= 6.4MS, 6.2mb, 06/04/2009 1:32:41.1, 42.51, 13.4, 10
EMSC= 6.3Mw, 06/04/2009 1:32:41.4, 42.38, 13.32, 2
GCMT= 6.3Mw, 6.3Ms, 5.9mb, 06/04/2009 1:32:49.2, 42.29, 13.35, 33

USGS MTS

gfz moment tensor solution
The best-fit inverted model indicates coseismic dip-slip displacement during the earthquake on a fault dipping 45º to the southwest with a maximum slip of about 80 cm at 7-9 km depth. The slip occurred close to the surface near the city of Paganica and three additional areas, one north and two south of Paganica.

Foreshocks

In the 90 days prior to the main shock there were 483 smaller earthquakes in the area;
1 mag 4.1, 9 mag 3.0 to 3.9, 75 mag 2.0-2.9 and 397 mag 1.0-1.9
The maps below show the accumulatiion of the events at 90, 60, 30, 14, 7 and 3 days points prior to the main shock
use the +/- zoom to view a wider area

90-60 days prior (cumulative)

cumulative 122, new 122

90-30 days prior (cumulative)

cumulative 256, new 134

90-14 days prior (cumulative)

cumulative 313, new 57

90-7 days prior (cumulative)

cumulative 339, new 26

90-72hrs days prior (cumulative)

cumulative 443, new 104 new events

90days-mainshock (cumulative)

cumulative 482, new 40

Foreshock Graphs

earthquakes in the L'Aquila area prior to 06/04/2009click on image for full size version, opens in new tab/window

Aftershocks

Mag 3.6+

The largest aftershock, a 5.4 occurred 40:14 hours after the main shock, near Fossa. In the following 187 hours (8days) there were a further three magnitude 5.0’s, two in Monte San Franco at 21:41TM (Time Mark) and at 187:41TM, and one in Passo Capannelle at the 90:05TM, also the location of a 5.1 at the 71:20 time mark.
All up in the 171 days (5.6 months) after the Main shock there were 33 aftershocks above magnitude 4.0 and 45 above (and including) 3.6.

Triggering

75 days (2.4 months) after the 6.3Mw on the 21st June at 16:31:11 a magnitude 3.3 hit Colle Verrico, north of the main L’Aquila aftershock series and another 3.3 on the 25th at 4:14:57 p.m.UTC before a 3.9 at 9:00:08 p.m.UTC setting of a side series of 1106 aftershocks with two 3.5’s, two 3.1’s and two 3.0’s in it, running in tandem with the main L’Aquila aftershock series through to the end of August.
The swarm of seismicity located fifteen miles N of L’Aquila in the vicinity of Lake Campotosto includes several events of magnitude around 5 and probably corresponds to the activation of a fault system separate from the Aquila.

The total number of aftershocks recorded in the 9 months to the end of 2009, was 17,039
The maps below show the locations of all the aftershocks, as marked in the titles.

12 hrs (cumulative)

showing cumulative 459, ( new 459)

24 hrs (cumulative)

showing cumulative 900, ( new 441)

72 hrs/3 days (cumulative)

showing cumulative 2,103, ( new 1,203)

7 days/168 hrs (cumulative)

showing cumulative 4,066, ( new 1,963)

Aftershock Graph 72hrs

Aftershock Graph 72hrsclick on image for full size version, opens in new tab/window

Aftershock Graph 7dayss

Aftershock Graph 7 daysclick on image for full size version, opens in new tab/window

more Aftershocks

7-14 days/168-336 hrs

showing new 2,454, ( cumulative 6,520)

14-30 days/336-720 hrs

showing new 2,531, ( cumulative 9,051)

30-60 days/720-1440 hrs

showing new 2,454, ( cumulative 11,415)

60-90 days/1440-2160 hrs

showing new 1798, ( cumulative 13,214)

90-120 days/2160-2880 hrs

showing new 1410, (cumulative 14,623)

120-150 days/2880-3600 hrs

showing new 945, ( cumulative 15,568)

150-180 days/3600-4320 hrs

showing new 1410, (cumulative 16,020)

180-210 days/4320-5040 hrs

showing new 357, ( cumulative 16,377)

210-240 days/5040-5760 hrs

showing new 467, (cumulative 16,844)

240-270 days/5760-6480 hrs

showing new 196, ( cumulative 17,040)

Aftershock Graph 30 days

Aftershock Graph 72hrsclick on image for full size version, opens in new tab/window

Google Earth file of all the Aftershocks


depending on your browser settings you may have to right click the link and “save link as ….” to your Downloads folder and then open it from there.
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Town Table

Numbers of aftershocks in relation to towns and villages in the area
Numbers of aftershocks in relation to towns and villages in the area