Fault Geometry and Active Stress from Earthquakes and Field Geology Data Analysis: The Colfiorito 1997 and L’Aquila 2009 Cases (Central Italy)

Ferrarini, Federica; Nardis, Rita de; Brozzetti, Francesco

doi:10.1007/s00024-014-0931-7

Cited by 49 publications

(62 citation statements)

References 67 publications

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“…The good consistency between the kinematics derived from 24 August, 30 October, and longer‐term slip indicators (Figure ) suggests there has been no major change in this state of stress over at least the last 10–20 ka, as suggested in previous studies (e.g., Ferrarini et al, ).…”

Section: Discussionsupporting

confidence: 80%

“…Interestingly, previous kinematic studies performed in the area (e.g., Boncio et al, ; Brozzetti & Lavecchia, ; Cello et al, ; Ferrarini et al, ) also concluded that faults between Colfiorito and L'Aquila are in a state of stress oblique to their main direction with right‐lateral component on more E‐W striking faults and left‐lateral component of more N‐S striking fault, also consistent with an extension at N50° ± 15°. Ferrarini et al (), in particular, compared the stress fields derived from 1997 Colfiorito earthquake focal mechanisms and the geological slip indicators. They found consistent stress field suggesting the persistence of a constant NE‐directed extension in the Umbria‐Marche region, at least since the Early Quaternary.…”

Section: Discussionsupporting

confidence: 55%

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Coseismic Slip Vectors of 24 August and 30 October 2016 Earthquakes in Central Italy: Oblique Slip and Regional Kinematic Implications

et al. 2018

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After 24 August and 30 October 2016 central Italy earthquakes (Mw 6.0 and 6.5, respectively), photogrammetry and geodetic survey were performed at various sites along a 6-km-long portion of the rupturing Monte Vettore fault system, providing very high-resolution georeferenced 3-D point clouds and imagery of the 24 August rupture and a data set of bedrock fault scarp before/after the 30 October earthquake. The maximum coseismic displacement for both events occurs near Scoglio dell' Aquila with an average normal dip slip of 22 ± 4 and 184 ± 6 cm, respectively. Coseismic slip vectors and meter-scale corrugation axis are oriented N280 ± 10°on the~N140°striking main Vettore fault involving oblique normal slip with a right-lateral component and N205 ± 10°on~N170°fault strands implying oblique normal slip with a left-lateral component. We quantify the near-field coseismic displacements of the Monte Vettore fault for the 30 October event: the footwall has been translated horizontally by 42 ± 2 cm toward the ENE and uplifted by 11 ± 2 cm. The hangingwall has moved horizontally by 26 ± 2 cm, toward the NW, in a direction parallel to the fault plane and subsided by 116 ± 2 cm. The fault geometry and our determined surface coseismic slip vectors are mechanically compatible with a σ3 = N65 ± 15°. This stress regime is consistent with the 30 October 2016 focal mechanism and the relative motion between the Adriatic microplate and the Tyrrhenian coastal region. The 30 October surface rupture results from seismic slip at depth and thus has a tectonic origin. Plain Language SummaryAfter 24 August and 30 October 2016 central Italy earthquakes, we acquire a very high-resolution data set of the effect of the fault at the surface before and after the 30 October earthquake. Those data sets allow quantifying the motion of each compartment on both side of the fault during the earthquake and the direction of this motion. The footwall has been translated horizontally by 42 ± 2 cm toward the ENE and uplifted by 11 ± 2 cm. The hangingwall has moved horizontally by 26 ± 2 cm, toward the NW, and subsided by 116 ± 2 cm. These results are consistent with the seismic data and suggest that surface ruptures observed are resulting from seismic slip at depth.In 2016, Italy was struck by an earthquake sequence that lasted several months with three shocks on 24 August, Mw = 6.0; 26 October, Mw = 5.9; and 30 October, Mw = 6.5 (Figure 1). This sequence occurred in Central Apennines, where NW-SE striking normal fault systems are accommodating~4 mm/year of PEROUSE ET AL. 3760

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Section: Discussionsupporting

confidence: 80%

Section: Discussionsupporting

confidence: 55%

Coseismic Slip Vectors of 24 August and 30 October 2016 Earthquakes in Central Italy: Oblique Slip and Regional Kinematic Implications

et al. 2018

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“…The kinematic of activated fault systems (VBFS and MLGFS) and the SW‐NE trending tensional active stress regime characterizing the Umbria‐Marche‐Abruzzo region (Ferrarini et al, ) are compatible with the focal mechanisms of the strongest events, mentioned above, with NNW‐SSE striking focal planes showing a normal dip‐slip mechanism.…”

Section: Introductionmentioning

confidence: 81%

Shear Wave Splitting Evidence and Relations With Stress Field and Major Faults From the “Amatrice‐Visso‐Norcia Seismic Sequence”

2019

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We present the largest dataset of anisotropic high‐quality parameters (~12,000) for the Amatrice‐Visso‐Norcia seismic sequence and investigate the physical mechanisms causing crustal anisotropy and its relation with crustal deformation, stress field, fluids, and earthquake generation. We performed shear wave splitting analysis on ~40,000 aftershocks recorded at 31 seismic stations during the first six months of the sequence following the 24 August 2016 Mw 6.0, Amatrice mainshock. Automatic and manual‐revised P‐ and S‐picking and high‐precision locations are used to delineate the fracturing pattern and spatio‐temporal variations in the anisotropic parameters: fast direction polarization (φ) and delay time (δt). The mean φ strikes N146°, parallel to the extensional Quaternary fault systems, and to the NW‐SE local active SHmax as proposed by the extensive dilatancy anisotropy model. Locally, φ directions outline the pattern of microscale and mesoscale structures that we relate to structural‐controlled anisotropy. Temporal variations of anisotropic parameters allowed us to deduce stress‐induced and pervasive fluid‐filled stress‐aligned crack systems as the prevalent anisotropic mechanisms in some sectors. Higher δt (>0.072 s) and higher anisotropy percentage (>1.5–2.0%) are found at the boundaries and in the western side of the activated fault systems, where heavily fractured carbonates are present. The fault network along with the lithological heterogeneities present in the area may act as a structural barrier along which fluids are channeled or trapped, thus causing overpressured fluid zones. Observations of shear‐wave splitting parameters during a seismic sequence can monitor the buildup of stress before earthquakes and the stress release as earthquakes occur.

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“…The Time Domain Moment Tensor focal mechanisms of the strongest events are normal dip-slip with NNW-SSE striking focal planes (http://cnt.rm.ingv.it/tdmt), therefore compatible with the kinematic of those faults and the SW-NE trending tensional stress regime characterizing the Umbria-Marche-Abruzzo region (Ferrarini et al 2015). Nevertheless, the depth distribution of hypocentres reveals the activation of a complex faults system, as suggested by early studies about the seismogenic source, which were mainly focused on the 24 August 2016 earthquake Lavecchia et al 2016;Michele et al 2016;Valensise et al 2016).…”

Section: Outline Of the Seismic Sequence And The Geology Of The Areamentioning

confidence: 88%

The Central Italy 2016–2017 seismic sequence: site response analysis based on seismological data in the Arquata del Tronto–Montegallo municipalities

Laurenzano

Barnaba

Romano

et al. 2018

Bull Earthquake Eng

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In this paper we evaluate the local seismic response for thirteen sites located in the municipalities of Arquata del Tronto and Montegallo, two areas which suffered heavy damage during the Mw 6.0 and Mw 5.4 earthquakes which struck Central Italy on August 24, 2016. The input dataset is made by ground motion recordings of 348 events occurred during the sequence. The spectral site response is estimated by the Generalized Inversion Technique and makes use of reference sites. The interpretation is further improved through the information provided by a reference-site independent method (i.e., the so called Receiver-Function Technique) and by the Horizontal-to-Vertical Spectral Ratios of ambient noise recordings. We also provide an independent estimate of the local amplification by comparing the Peak Ground Velocity and the Spectral Amplitudes observed at each site to the value estimated by well-established Ground Motion Prediction Equations for a rock-class site. The results obtained by the adopted methodologies are all highly consistent, and they emphasize the different seismic behavior of several sites at local scale. Thus, sites located on Quaternary deposits overlying the bedrock, such as Castro, Pretare, Spelonga, Pescara del Tronto, and Capodacqua feature some relevant amplifications in a medium (2-10 Hz) frequency range; two sites at Spelonga show amplifications also at low frequencies; three sites located on stiff formations, i.e. Uscerno, Balzo and Colle d'Arquata, respectively, feature either nearly neutral response or low amplification level. A probable topographic effect was identified at the rock site of Rocca di Arquata (MZ80).

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Fault Geometry and Active Stress from Earthquakes and Field Geology Data Analysis: The Colfiorito 1997 and L’Aquila 2009 Cases (Central Italy)

Cited by 49 publications

References 67 publications

Coseismic Slip Vectors of 24 August and 30 October 2016 Earthquakes in Central Italy: Oblique Slip and Regional Kinematic Implications

Coseismic Slip Vectors of 24 August and 30 October 2016 Earthquakes in Central Italy: Oblique Slip and Regional Kinematic Implications

Shear Wave Splitting Evidence and Relations With Stress Field and Major Faults From the “Amatrice‐Visso‐Norcia Seismic Sequence”

The Central Italy 2016–2017 seismic sequence: site response analysis based on seismological data in the Arquata del Tronto–Montegallo municipalities

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