On April 6th 2009, a 6. earthquake has shaken Central Italy in L’Aquila area.
The following maps show the evolution of the seismicity across April Month, using the INGV Catalog :

2009 foreshocks	aftershocks on April 9th	aftershocks on April 13th
aftershocks on April 20th	aftershocks on April 26th	aftershocks on May 12th
	aftershocks on June 30th

Geoazur has been analysing the main shock of L’Aquila crisis using three differents methods described below :

1. the INSAR Inversion method
2. the Fast Teleseismic Bodywaves Source Inversion method
3. the Regional Broadband Source Inversion method

You can also consult the specific pages from other institutes here.

INSAR INVERSION

Bertrand Delouis (Géoazur, UNS, Nice, France, delouis@geoazur.unice.fr)

Fast teleseismic bodywaves source inversion

Martin Vallée (Géoazur, IRD, Nice, France, vallee@geoazur.unice.fr)
Jean Charléty (Géoazur, CNRS, Nice, France, charlety@geoazur.unice.fr)
Collaboration with LDG/CEA

This event is a very superficial ( 4km depth) extensional earthquake (figure 1).
We have deconvolved the P-wave teleseismic signals (see figure 2) of FDSN stations (including Geoscope) to retrieve the source time functions in a broad frequency band (0.0125-0.8Hz).
In this frequency band, the earthquake is not particularly impulsive (the source time functions mainly include a broad 8-10s long pulse).
Its very shallow depth and the vicinity of L’Aquila town were probably the main reasons for the extensive damage reported. 

Update : 2009/04/08

Regional broadband source inversion

Bertrand Delouis (Géoazur, UNS, Nice, France, delouis@geoazur.unice.fr)

We also performed a source inversion using the french broadband stations. This more regional analysis based on a limited set of records allowed us to determine the focal machanism, in agreement with the more global studies. We imposed the hypocentral depth at 9 km as found by the INGV. The relatively low moment magnitude (Mw) found (6.04) could be related to the limited dataset and frequency band used. Secondary solutions correspond to secondary minima of the misfit function found by the grid search inversion. Solutions with the lowest mistfit clearly indicate NW-SE planes with normal faulting.

see also the specific information from...

• Istituto Nazionale di Geofisica e Vulcanologia (INGV Roma)
• Euromediterranean Seismological Center (EMSC)
• Institut de Physique du globe de Paris (IPGP)
• Géoscope (IPGP)
• Centre de l’Energie Atomique (CEA)
• Institut de Radioprotection et de Sureté Nucléaire (IRSN)
• U.S. Geological Survey (USGS)