Coseismic deformation of the destructive April 6, 2009 L'Aquila earthquake (central Italy) from GPS data

Abstract

On April 6, 2009, 01:32:39 GMT, the city of L'Aquila was struck by a Mw 6.3 earthquake that killed 307 people, causing severe destruction and ground cracks in a wide area around the epicenter. Four days before the main shock we augmented the existing permanent GPS network with five GPS stations of the Central Apennine Geodetic Network (CaGeoNet) bordering the L'Aquila basin. The maximum horizontal and vertical coseismic surface displacements detected at these stations was 10.39 ± 0.45 cm and −15.64 ± 1.55 cm, respectively. Fixing the strike direction according to focal mechanism estimates, we estimated the source geometry with a non linear inversion of the geodetic data. Our best fitting fault model is a 13 × 15.7 km2 rectangular fault, SW‐dipping at 55.3 ± 1.8°, consistent with the position of observed surface ruptures. The estimated slip (495 ± 29 mm) corresponds to a 6.3 moment magnitude, in excellent agreement with seismological data.

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

“…DInSAR values correlate well with GPS recordings from near field GPS stations. The maximum vertical displacement was recorded from a GPS station near the village of Fossa (∼16 cm of subsidence, Anzidei et al, 2009) and is in agreement with the DInSAR values. Figure 8 shows the range of the observed ground deformation in the epicentral area as appears from all profiles.…”

“…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

“…In addition, the assumed strike and dip are within the range of values inferred from moment tensor solutions (see Data and Resources). The distribution of aftershocks and GPS displacements (Anzidei et al, 2009) also contributed to the identification of the fault geometry. determine a heterogeneous fault-slip distribution (see Fig.…”

“…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).…”

The anatomy of the 2009 L'Aquila normal fault system (central Italy) imaged by high resolution foreshock and aftershock locations

“…Further details on fault geometry and slip distribution were derived from the modeling of Global Position System (GPS), synthetic aperture radar (SAR) data [Walters et al, 2009;Atzori et al, 2009;Anzidei et al, 2009;Cheloni et al, 2010;Lanari et al, 2010] and by the joint inversion of strong motion and geodetic data [Cirella et al, 2009].…”