Fluid flow and seismicity pattern: Evidence from the 1997 Umbria‐Marche (central Italy) seismic sequence

Antonioli, Andrea; Piccinini, D.; Chiaraluce, L.; Cocco, M.

doi:10.1029/2004gl022256

Cited by 111 publications

(104 citation statements)

References 21 publications

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“…On 5 April, a few hours before the occurrence of the 01:32 main shock, seismicity went back to activate the L'Aquila plane. 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.…”

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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“…For many seismological aspects, e.g. Antonioli et al (2005), the seismic area of Umbria-Marche (central Italy) and surroundings is of particular interest. For this area, the catalog in the period 1981-1996 at latitudes 41.5-44.5 N and the sequence in the period 1997-1998 were analyzed (sets UM).…”

Section: Data Analysis and Resultsmentioning

confidence: 99%

“…These could be induced by some mechanism triggering the seismicity (Godano and Pingue, 2005;Tosi, 2004). For the UM sequence this can be identified in the pore-fluid flow (see Antonioli et al, 2005 and references therein). The properties of the catalogues data sets seem to be very similar among them with a slight but significant deviation for California.…”

Section: Discussionmentioning

confidence: 99%

Statistical properties of earthquakes clustering

Vecchio

Carbone

Sorriso‐Valvo³

et al. 2008

Nonlin. Processes Geophys.

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Abstract. Often in nature the temporal distribution of inhomogeneous stochastic point processes can be modeled as a realization of renewal Poisson processes with a variable rate. Here we investigate one of the classical examples, namely, the temporal distribution of earthquakes. We show that this process strongly departs from a Poisson statistics for both catalogue and sequence data sets. This indicate the presence of correlations in the system probably related to the stressing perturbation characterizing the seismicity in the area under analysis. As shown by this analysis, the catalogues, at variance with sequences, show common statistical properties.

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“…fluid-injection induced earthquakes (e.g. Shapiro et al 1997;Rothert and Shapiro 2003;Shapiro et al 2003;Antonioli et al 2005), reservoir induced (e.g. Ferreira et al 1995); intraplate earthquake swarms (e.g.…”

Section: Pore Presssue Perturbationmentioning

confidence: 99%

“…On the contrary, if the earthquake triggering occurs shortly after the pore pressure perturbations (Noir et al 1997), we should observe a narrow cluster of seismicity along the line of the modelled parabola in the r-t plot with variable scalar D values. The D-value in the earth's crust usually ranges between 0.1 and 10 m 2 /s (Shapiro et al 1999) but can reach to 90 m 2 /s (Antonioli et al 2005) but there is no upper limit. In this scheme the r-t plot basically represents spatial distance ''r'' of an individual event from the injection point as a function of time ''t''.…”

Section: Pore Presssue Perturbationmentioning

confidence: 99%

Incipient status of dyke intrusion in top crust – evidences from the Al-Ays 2009 earthquake swarm, Harrat Lunayyir, SW Saudi Arabia

Mukhopadhyay

Mogren

Mukhopadhyay

et al. 2013

Geomatics, Natural Hazards and Risk

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The 2009 earthquake-swarm in the Al-Ays volcanic zone in Harrat-Lunayyir in NW Saudi-Arabia is unique because of its intense character and focal-depth distribution at two depth bands (5-10 and 15-20 km) in upper crust without volcanic eruption. We investigate an anatomy of the dyke-intrusion model that supports the mechanism for the swarm itself with seismotectonics, pore pressure diffusion process and inference model. Inferred dyke-intrusion initially started at depth had a five-day peak period (15-20 May 2009) since inception of eventrecordings, following which the activity diminished. The process of pore pressure perturbation and resultant ''r-t plot'' with modelled diffusivity (D ¼ 0.01) relates the diffusion of pore pressure to seismic sequence in a fractured poro-elastic fluidsaturated medium. The spatio-temporal b-values show high b-values (41.3) along the zone of dyke intrusion (length 10 km and height 5 km) at *20km depth. The main-shock and other prominent earthquakes originated on a moderate b-value zone (*1.0). Temporal b-value analysis indicates an exceptionally low b-value (*0.4) during the main-shock occurrence. The AlAys lava-field is inferred to underlie a seismic volume trending NW-SE bounded on both sides by two NW-SE trending fault systems, dipping 40-508 opposite to each other within a proposed nascent rift setting.

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Fluid flow and seismicity pattern: Evidence from the 1997 Umbria‐Marche (central Italy) seismic sequence

Cited by 111 publications

References 21 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

Statistical properties of earthquakes clustering

Incipient status of dyke intrusion in top crust – evidences from the Al-Ays 2009 earthquake swarm, Harrat Lunayyir, SW Saudi Arabia

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