Aeromagnetic investigation of southern Calabria and the Messina Straits (Italy): Tracking seismogenic sources of 1783 and 1908 earthquakes

Abstract

Southern Calabria and the NE corner of Sicily (Italy) were struck in 1783 and 1908 A.D. by two of the most catastrophic earthquakes ever in European history. Although it is generally acknowledged that the seisms were yielded by normal faults rupturing the upper crust of the Calabria‐Peloritani terrane, no consensus exists on seismogenic source location and orientation. Here we report on a high‐resolution low‐altitude aeromagnetic survey of southern Calabria and Messina Straits. In southern Calabria we document a broad weakly positive (5–10 nT) anomaly zone interrupted by three en echelon SW‐NE null to negative magnetic anomaly corridors. Euler deconvolution and magnetic modeling show that the anomaly pattern is produced by a 1–1.5 km thick crustal “layer” located within 3 km depth. This layer is offset by a 25 km long NE trending fault that corresponds to the Armo normal fault, recently inferred to be the source for the 1908 earthquake. Few kilometers to the south, we also document a subparallel and previously unrecognized fault, entering the Messina Straits and likely joining the Armo fault at depth. Further east, we model a 40 km long normal fault, probably extending northeastward for additional 40 km, running along the south Calabria axis from Aspromonte to the Serre mountains and partly following the 18 km long surface rupture witnessed by Déodat de Dolomieu after the 1783 earthquake. Thus, aeromagnetic data suggest that the sources of the 1783 and 1908 earthquakes are en echelon faults belonging to the same NW dipping normal fault system straddling the whole southern Calabria.

Aeromagnetic Investigation of the Central Apennine Seismogenic Zone (Italy): From Basins to Faults

“…Conversely, other studies (e.g., Grauch, ; Hudson et al, ) showed that also faults crosscutting lower magnetization continental sediments can be highlighted by aeromagnetic maps. Recently, Minelli et al () related the aeromagnetic residual anomalies of south Calabria (Italy) to the faults responsible of the catastrophic 1783 and 1908 earthquakes and suggested that magnetic anomalies are generated by an unexposed ophiolitic layer displaced by active normal faults. In all such cases, the magnetic image of active faults seems rather obvious, as they cut strongly magnetic rocks (basic volcanics and ophiolites) or continental sediments, which are known for generating lower but not negligible induced magnetization, in the order of 5 × 10 −3 A/m at midlatitudes.…”

A “Geodetic Gap” in the Calabrian Arc: Evidence for a Locked Subduction Megathrust?

“…Using (a) updated GPS horizontal velocities (Devoti et al, 2017), (b) a detailed 3-D reconstruction of the subduction interface geometry (Maesano et al, 2017), (c) a recent release of the Italian earthquake catalog (Rovida et al, 2016), and (d) upper crustal fault geometries (Database of Individual Seismogenic Sources Working Group, 2015;Minelli et al, 2016), we investigated the short-term behavior of the Calabrian subduction zone and its potential role in explaining the observed, anomalously low strain rates.…”

“…The digital elevation model (DEM) is fromRyan et al (2009). (b) NW (fromAloisi et al, 2012;Galli & Bosi, 2002, 2003Galli & Peronace, 2015;Galli & Scionti, 2006;Minelli et al, 2016), SE (from DISS Working Group, 2015;Tiberti et al, 2017) dipping active fault data sets and subduction interface geometry. (c) Three-dimensional view of the broader study area is toward SSE.…”

Application of an Improved Calibration Flight Scheme in Aeromagnetic Interference Compensation

“…It has important applications in the fields of geomagnetic navigation background field construction, mineral resources development, seismogenic sources tracking, hidden tectonic and volcanic structures revealment, etc. (Beamish & White, 2011; De Ritis et al., 2010; Goodge & Finn, 2010; Hood, 2007; Liu et al., 2018, 2021; Minelli et al., 2016).…”