Temporal variation of seismic velocity and anisotropy before the 2009 MW6.3 L'Aquila earthquake, Italy

Lucente, Francesco Pio; Gori, Pasquale De; Margheriti, Lucia; Piccinini, D.; Bona, M. Di; Chiarabba, C.; Agostinetti, Nicola Piana

doi:10.1130/g31463.1

Cited by 174 publications

(153 citation statements)

References 19 publications

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“…In extensional environments, seismicity migration episodes along preferred directions during both foreshock and aftershock sequences are often related to diffusion processes [Noir et al, 1997;Miller et al, 2004;Antonioli et al, 2005]. It is worth noting that the occurrence of the largest foreshock, about a week before the main shock, signed a sharp variation in the V P /V S ratio modeled by Lucente et al [2010] in terms of a dilatancy diffusion process suggesting a key role for fluids in the nucleation process. We also observe seismicity migration during the two days after the main shock, when the earthquakes moved along strike: from the L'Aquila area toward the Campotosto village (NW direction).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2011

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[1] On 6 April (01:32 UTC) 2009 a M W 6.1 normal faulting earthquake struck the axial area of the Abruzzo region in central Italy. We study the geometry of fault segments using high resolution foreshock and aftershock locations. Two main SW dipping segments, the L'Aquila and Campotosto faults, forming an en echelon system 40 km long (NW trending). The 16 km long L'Aquila fault shows a planar geometry with constant dip (∼48°) through the entire upper crust down to 10 km depth. The Campotosto fault activated by three events with 5.0 ≤ M W ≤ 5.2 shows a striking listric geometry, composed by planar segments with different dips along depth rather than a smoothly curving single fault surface. The investigation of the spatiotemporal evolution of foreshock activity within the crustal volume where the subsequent L'Aquila main shock nucleated allows us to image the progressive activation of the main fault plane. From the beginning of 2009 the foreshocks activated the deepest portion of the fault until a week before the main shock, when the largest foreshock (M W 4.0) triggered a minor antithetic segment. Seismicity jumped back to the main plane a few hours before the main shock. Secondary synthetic and antithetic fault segments are present both on the hanging and footwall of the system. The stress tensor obtained by inverting focal mechanisms of the largest events reveals a NE trending extension and the majority of the aftershocks are kinematically consistent. Deviations from the dominant extensional strain pattern are observed for those earthquakes activating minor structures.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2011

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“…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).…”

Section: Introductionmentioning

confidence: 99%

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

Magnoni¹,

Casarotti²,

Michelini³

et al. 2013

Bulletin of the Seismological Society of America

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We adopt a spectral-element method (SEM) to perform numerical simulations of the complex wavefield generated by the 6 April 2009 M w 6.3 L'Aquila earthquake in central Italy. The mainshock is represented by a finite-fault solution obtained by inverting strong-motion and Global Positioning System data, testing both 1D and 3D wavespeed models for central Italy. Surface topography, attenuation, and the Moho discontinuity are also accommodated. Including these complexities is essential to accurately simulate seismic-wave propagation. Three-component synthetic waveforms are compared to corresponding velocimeter and strong-motion recordings. The results show a favorable match between data and synthetics up to ∼0:5 Hz in a 200 km × 200 km × 60 km model volume, capturing features mainly related to topography or low-wavespeed basins. We construct synthetic peak ground velocity maps that, for the 3D model, are in good agreement with observations, thus providing valuable information for seismic-hazard assessment. Exploiting the SEM in combination with an adjoint method, we calculate finite-frequency kernels for specific seismic arrivals. These kernels capture the volumetric sensitivity associated with the selected waveform and highlight prominent effects of topography on seismic-wave propagation in central Italy.

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“…in the same epoch when Lucente et al (2010) hypothesised the occurrence of some diffusion of fluids under the hypocentral region; on the other hand, the same results do not exclude the possibility that these processes actually happened. If they occurred, they were too rapid and not detectable with our techniques.…”

Section: G Cianchini Et Al: Magnetic Transfer Function Entropymentioning

confidence: 47%

“…Is it possible to link those features to some tectonic causes, such as, for instance, the fluid migration during crack opening (e.g. Lucente et al, 2010)?…”

Section: G Cianchini Et Al: Magnetic Transfer Function Entropymentioning

confidence: 99%

“…Lucente et al (2010) reported a sudden change of the V p /V s ratio between the seismic wave velocities and of the S-wave polarisation just after the onset of the large M L = 4.1 earthquake on 30 March 2009 that preceded the main shock by a week. These authors interpreted their results as having been caused by migration of fluids moving from the fault footwall, where they had previously been sealed, towards the hanging wall.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic transfer function entropy and the 2009 Mw = 6.3 L'Aquila earthquake (Central Italy)

Cianchini

Santis

Barraclough

et al. 2012

Nonlin. Processes Geophys.

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Abstract. With the aim of obtaining a deeper knowledge of the physical phenomena associated with the 2009 L'Aquila (Central Italy) seismic sequence, culminating with a M w = 6.3 earthquake on 6 April 2009, and possibly of identifying some kind of earthquake-related magnetic or geoelectric anomaly, we analyse the geomagnetic field components measured at the magnetic observatory of L'Aquila and their variations in time. In particular, trends of magnetic transfer functions in the years 2006-2010 are inspected. They are calculated from the horizontal to vertical magnetic component ratio in the frequency domain, and are very sensitive to deep and lateral geoelectric characteristics of the measurement site. Entropy analysis, carried out from the transfer functions with the so called transfer function entropy, points out clear temporal burst regimes of a few distinct harmonics preceding the main shock of the seismic sequence. A possible explanation is that they could be related to deep fluid migrations and/or to variations in the micro-/meso-fracturing that affected significantly the conductivity (ordered/disordered) distribution in a large lithospheric volume under the seismogenic layer below L'Aquila area. This interpretation is also supported by the analysis of hypocentres depths before the main shock occurrence.

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Temporal variation of seismic velocity and anisotropy before the 2009 M_W6.3 L'Aquila earthquake, Italy

Cited by 174 publications

References 19 publications

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

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

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

Magnetic transfer function entropy and the 2009 <i>M</i><sub>w</sub> = 6.3 L'Aquila earthquake (Central Italy)

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Temporal variation of seismic velocity and anisotropy before the 2009 MW6.3 L'Aquila earthquake, Italy

Cited by 174 publications

References 19 publications

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

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

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

Magnetic transfer function entropy and the 2009 &lt;i&gt;M&lt;/i&gt;&lt;sub&gt;w&lt;/sub&gt; = 6.3 L'Aquila earthquake (Central Italy)

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Temporal variation of seismic velocity and anisotropy before the 2009 M_W6.3 L'Aquila earthquake, Italy

Magnetic transfer function entropy and the 2009 <i>M</i><sub>w</sub> = 6.3 L'Aquila earthquake (Central Italy)