Heterogeneous Behavior of the Campotosto Normal Fault (Central Italy) Imaged by InSAR GPS and Strong-Motion Data: Insights from the 18 January 2017 Events

Remote Sensing

Roberta Giuliani¹  Maurizio Mattone¹  Daniele Cheloni²  Nicola D’Agostino²  Christian Bignami²  Antonio Avallone²  Laura Scognamiglio²  Elisa Tinti²  Stefano Calcaterra³  Piera Gambino³ 

[1] Dipartimento della Protezione Civile, Via Vitorchiano 4, 00189 Rome, Italy;Istituto Nazionale di Geofisica e Vulcanologia (INGV), 00143 Rome, Italy;Istituto Superiore per la Protezione e la Ricerca Ambientale, Via Vitaliano Brancati 48, 00144 Rome, Italy;

关键词: InSAR;    Sentinel-1;    GPS;    high-rate GPS;    strong-motion;    normal faulting earthquake;    continental tectonic;    source modeling;    central Italy;    kinematic inversion;    seismic cycle;   

DOI  :  10.3390/rs11121482

来源: DOAJ

【 摘 要 】

On 18 January 2017, the 2016−2017 central Italy seismic sequence reached the Campotosto area with four events with magnitude larger than 5 in three hours (major event M_W 5.5). To study the slip behavior on the causative fault/faults we followed two different methodologies: (1) we use Interferometric Synthetic Aperture Radar (InSAR) interferograms (Sentinel-1 satellites) and Global Positioning System (GPS) coseismic displacements to constrain the fault geometry and the cumulative slip distribution; (2) we invert near-source strong-motion, high-sampling-rate GPS waveforms, and high-rate GPS-derived static offsets to retrieve the rupture history of the two largest events. The geodetic inversion shows that the earthquake sequence occurred along the southern segment of the SW-dipping Mts. Laga normal fault system with an average slip of about 40 cm and an estimated cumulative geodetic moment of 9.29 × 10¹⁷ Nm (equivalent to a M_W~6). This latter estimate is larger than the cumulative seismic moment of all the events, with M_W > 4 which occurred in the corresponding time interval, suggesting that a fraction (~35%) of the overall deformation imaged by InSAR and GPS may have been released aseismically. Geodetic and seismological data agree with the geological information pointing out the Campotosto fault segment as the causative structure of the main shocks. The position of the hypocenters supports the evidence of an up-dip and northwestward rupture directivity during the major shocks of the sequence for both static and kinematic inferred slip models. The activated two main slip patches are characterized by rise time and peak slip velocity in the ranges 0.7−1.1 s and 2.3−3.2 km/s, respectively, and by ~35−50 cm of slip mainly concentrated in the shallower northern part of causative fault. Our results show that shallow slip (depth < 5 km) is required by the geodetic and seismological observations and that the inferred slip distribution is complementary with respect to the previous April 2009 seismic sequence affecting the southern half of the Campotosto fault. The recent moderate strain-release episodes (multiple M~5−5.5 earthquakes) and the paleoseismological evidence of surface-rupturing events (M~6.5) suggests therefore a heterogeneous behavior of the Campotosto fault.

【 授权许可】

Unknown