Structure and properties of the Adriatic crust in the central‐eastern Southern Alps (Italy) from local earthquake tomography

Abstract

Structure and properties of the Adriatic crust were determined from local earthquake tomography around the Giudicarie fault zone (central‐eastern Southern Alps, Italy). Tomographic results, based on well‐suited 436 revised earthquakes (period 1994–2007), have a resolution comparable to the scale of regional geological domains and tectonic structures. The observed strong velocity anomalies correlate well with lithological variations corresponding to different geological domains (particularly magmatic complexes at depth) and with high fracturing and/or presence of fluids along active fault systems (South Giudicarie and Valsugana–Bassano del Grappa–Montello thrusts).

Deriving a New Crustal Model of Northern Adria: The Northern Adria Crust (NAC) Model

“…We followed Artemieva and Thybo (2013) to assign V P accuracy to the different seismic profiles. Local earthquake tomography studies provide information about V P and V S in the Southern Alps and External Dinarides (Anselmi et al, 2011;Viganò et al, 2013). Gravimetric studies at regional scale provide information on the density of the crustal layers (Braitenberg et al, 1997;Cassinis et al, 1997;Dal Moro et al, 1998;Ebbing et al, 2001Ebbing et al, , 2006Šumanovac et al, 2009;Šumanovac, 2010).…”

“…The 2D velocity model of each seismic section was converted into a set of 1D velocity profiles. We took the V P values from local earthquake tomography only for those nodes identified by and Anselmi et al (2011) as reliable according to a threshold of the spread function (a measure of the blurring of the tomographic image) and by Viganò et al (2013) according to checkerboard, recovery, and synthetic data tests. The data was transformed from the geographical coordinates to a Cartesian coordinate system to obtain a regular spacing in the area and to convert the model in a mesh suitable for numerical modeling.…”

“…The physical properties (namely: seismic velocities, rock bulk density, and elastic moduli) of the upper crust of the Friuli seismic region were studied through laboratory measurements on rock samples, representative of the most common lithologies, sonic logs, local earthquake tomography, and seismo-gravimetric inversion (Faccenda et al, 2007;. Local earthquake tomography was also applied in other parts of the Southern Alps (Anselmi et al, 2011;Viganò et al, 2013).…”

Past to present deformation of the central-eastern Southern Alps: from the foreland to the Giudicarie belt

“…The central-eastern Southern Alps are one of the most active areas of the Alpine belt where seismicity is related to deformation along the western margin of the Adriatic indenter (Slejko et al, 1989;Viganò et al, 2008;. Deep seismic soundings show a complex structure of the Adriatic crust with local fragmentation and lower crust wedges, as similarly observed for upper crustal strong heterogeneities by local earthquake tomography (Viganò et al, 2013a). At the lithospheric scale, seismic tomography suggests an abrupt change of polarity of subduction along the Giudicarie realm (Europe subduction in the Western Alps vs. Adria subduction in the Eastern Alps; Kissling et al, 2006 and references therein).…”

Structural and climate drivers of the historic Masiere di Vedana rock avalanche (Belluno Dolomites, NE Italy)

“…The Veneto region is prone to earthquake activity and is categorized as level 2 seismic hazard ("possible strong earthquakes" in Ordinanza del PCM n. 3519/2006), as the historical record testifies (up to~Mw=6.5;Vigano`et al, 2013Vigano`et al, , 2015Rovida et al, 2016). Continuous instrumental monitoring of the Belluno area dates back only to 1977 (Sandron et al, 2014), preceding cataloged major seismic events in the region are based on either historical chronicles, dated building damages and/or observed rockfalls (Piloni, 1607;Taramelli, 1883;Guidoboni et al, 2005Guidoboni et al, , 2018.…”