Finite fault inversion of DInSAR coseismic displacement of the 2009 L'Aquila earthquake (central Italy)

Abstract

We define the geometric and kinematic characteristics of the fault activated during the Mw = 6.3, 6 April 2009 L'Aquila earthquake, from the modeling of Envisat and COSMO‐SkyMed (the first ever X‐band interferogram inverted for a coseismic dislocation study) DInSAR interferograms. Our best‐fit solution for the main shock is represented by a normal fault ∼16 km long and ∼12 km wide, with a small right‐lateral component, dipping 47°SW with a maximum slip of ∼90 cm. Although the seismic dislocation probably ended at 1 km depth, the updip projection of the fault plane corresponds to the northern segment of the mapped Paganica–S. Demetrio fault, where alignment of surface breaks was observed in the field. The absence of this fault in existing seismic source catalogues suggests that an improved approach, involving detailed surface and subsurface geological and geophysical investigations, is needed for a better assessment of the seismic hazard at the local scale.

Deformation pattern of the 6 and 7 April 2009, <i>M</i><sub>W</sub>=6.3 and <i>M</i><sub>W</sub>=5.6 earthquakes in L'Aquila (Central Italy) revealed by ground and space based observations

“…This occurs not only because the Paganica ruptures correlate with well the focal mechanism and the epicenter locality (e.g. Chiarabba et al, 2009), but mainly due to the DInSAR analysis results (see also Atzori et al, 2009;Walters et al, 2009). In particular, the approximately 7 km long DIn-SAR predicted fault surface ruptures coincide with the surface ruptures observed in Paganica since they are only a couple of hundred meters up to 1 km apart (Fig.…”

“…The earthquake was assessed as a M W =6.2 or M L =5.8 (source INGV) or M W =6.3 (USGS), having a normal faulting mechanism of N147 • striking and dipping about 43 • towards the SW and a focal depth at 9 km. InSAR, body wave seismology and GPS data determined a SW∼50 • dipping normal fault with a maximum ∼0.6-0.9 m slip (Walters et al, 2009;Atzori et al, 2009;Anzidei et al, 2009). The epicenter was located a few km WSW from the city of L'Aquila which including the surrounding villages, hosts a population of about 100 000.…”

Spectral-Element Simulations of Seismic Waves Generated by the 2009 L'Aquila Earthquake

“…They adopt a fault plane with a strike of N133°E and a dip of 54°to the southwest. The strike direction is taken from a Synthetic Aperture Radar interferometric data analysis (Atzori et al, 2009). The dip value is consistent with both the hypocenter location and observed surface breakages (EMERGEO Working Group, 2010).…”

“…Imaging of the source (Anzidei et al, 2009;Atzori et al, 2009;Cirella et al, , 2012Pino and Di Luccio, 2009;Cheloni et al, 2010;Scognamiglio et al, 2010) highlights a complex rupture history composed of two main slip releases and controlled by spatial variations of material properties along the fault Lucente et al, 2010;Di Stefano, Chiarabba, et al, 2011) as well as temporal variations (Lucente et al, 2010;Zaccarelli et al, 2011). The source characteristics are partly responsible for the southeast directivity (Pino and Di Luccio, 2009;Akinci et al, 2010) and the unusually high levels of strong acceleration recorded close to L'Aquila city Çelebi et al, 2010).…”

Strong foreshock signal preceding the L'Aquila (Italy) earthquake (<i>M</i><sub>w</sub> 6.3) of 6 April 2009

“…The strong (M w = 6.3) earthquake of 6 April 2009 in L'Aquila, Central Italy, occurred at 01:32:39 UTC and caused about 300 deaths and destruction in about 60 000 buildings of the area. The geometric and kinematic features and the source properties of the earthquake were studied by Atzori et al (2009), Cirella et al (2009 and Walters et al (2009). It has been shown that the earthquake rupture very possibly was associated with the Paganica normal fault which strikes NW-SE and dips SW (Fig.…”