Source parameters and triggering links of the earthquake sequence in central Italy from 2009 to 2016 analyzed with GPS and InSAR data

• Published in: Tectonophysics Vol. 744; pp. 285 - 295
• Main Authors: Wang, Leyang, Gao, Hua, Feng, Guangcai, Xu, Wenbin
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02.10.2018; Elsevier BV
• Subjects: 2016 Central Italy earthquakes; Coulomb stress change and triggering relation; Deformation; Deformation mechanisms; Earthquakes; Fault lines; Focal parameters inversion by InSAR and GPS data; Global positioning systems; GPS; Interferometric synthetic aperture radar; Parameter estimation; Plate tectonics; Positioning systems; Radar; Radar data; SAR (radar); Satellite navigation systems; Seismic activity; Seismic engineering; Stress; Stresses; Synthetic aperture radar; Synthetic aperture radar interferometry; Italy; Coulomb stress change and triggering relation; Focal parameters inversion by InSAR and GPS data; 2016 Central Italy earthquakes
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2018.07.013

From 2009 to 2016, four earthquakes (Mw > 6) occurred in central Italy, which are the Apr. 6th, 2009 earthquake, Aug. 24th, 2016 earthquake, Oct. 26th, 2016 earthquake and Oct. 30th, 2016 earthquake. To investigate their seismic mechanism, triggering relationships and impacts on the surrounding areas, we obtained their coseismic deformation fields using the data of interferometric synthetic aperture radar (InSAR) and global positioning system (GPS). We constructed three variable-strike fault models for the four events which can be more consistent with the actual fault and improve the overall fitting precision. On this basis, we calculated the coseismic slips of the first two earthquakes respectively and obtained that of the last two earthquakes by a joint inversion method. Then the Coulomb stress changes of those four earthquakes were calculated. The results show that these earthquakes are mainly caused by normal faults that strike approximately NW-SE or NNW-SSE and dips to SW or WSW with angles between 33° and 47°. All these events are shallow earthquakes, and the main fault slips are located in the area with depth of 0–10 km, accompanied by some surface ruptures. The maximal slip with a value of 3.44 m at ~4 km depth was caused by the Oct. 30th, 2016 earthquake. The inverted magnitudes of the four earthquakes are Mw 6.26, Mw 6.20, Mw 6.19 and Mw 6.60. The stress changes indicate that the former earthquake accelerated the latter one successively. Moreover, there is a seismic gap between the regions of the Apr. 6th, 2009 and Aug. 24th, 2016 earthquakes and a high stress-accumulating area in the south of the Apr. 6th, 2009 earthquake region. So, the Montereale fault in the gap and the Barisciano fault located on the southeast of the Paganica fault might have great earthquake risks due to the massive accumulated stress. •Coseismic deformation of the four earthquakes (Mw > 6) occurred in central Italy.•These earthquakes are caused by normal faults with some strike-slip component.•Stress changes indicate the former earthquake accelerated the latter one successively.•There is a seismic gap and a high stress-accumulating area may have earthquake risks.