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1. A buried volcano in the Calabrian Arc (Italy) revealed
by high‐resolution aeromagnetic data
R. De Ritis,1
R. Dominici,2
G. Ventura,1
I. Nicolosi,1
M. Chiappini,1
F. Speranza,1
R. De Rosa,2
P. Donato,2
and M. Sonnino2
Received 26 November 2009; revised 8 June 2010; accepted 18 June 2010; published 4 November 2010.
[1] Aeromagnetic data collected between the Aeolian volcanoes (southern Tyrrhenian
Sea) and the Calabrian Arc (Italy) highlight a WNW‐ESE elongated positive magnetic
anomaly centered on the Capo Vaticano morphological ridge (Tyrrhenian coast of
Calabria), characterized by an apical, subcircular, flat surface. Results of forward
and inverse modeling of the magnetic data show a 20 km long and 3–5 km wide
magnetized body that extends from sea floor to about 3 km below sea level. The magnetic
properties of this body are consistent with those of the medium to highly evolved
volcanic rocks of the Aeolian Arc (i.e., dacites and rhyolites). In the Calabria mainland,
widespread dacitic to rhyolitic pumices with calc‐alkaline affinity of Pleistocene age
(1–0.7 Ma) are exposed. The tephra falls are related to explosive activity and show a
decreasing thickness from the Capo Vaticano area southeastward. The presence of lithics
indicates a provenance from a source located not far from Capo Vaticano. The combined
interpretation of the magnetic and available geological data reveal that (1) the Capo
Vaticano WNW‐ESE elongated positive magnetic anomaly is due to the occurrence
of a WNW‐ESE elongated sill; (2) such a sill represents the remnant of the plumbing
system of a Pleistocene volcano that erupted explosively producing the pumice tephra
exposed in Calabria; and (3) the volcanism is consistent with the Aeolian products,
in terms of age, magnetic signature, and geochemical affinity of the erupted products,.
The results indicate that such volcanism developed along seismically active faults
transversal to the general trend of the Aeolian Arc and Calabria block, in an area where
uplift is maximized (∼4 mm/yr). Such uplift could also be responsible for fragmentation
of the upper crust and formation of transversal faults along which seismic activity and
volcanism occur.
Citation: De Ritis, R., R. Dominici, G. Ventura, I. Nicolosi, M. Chiappini, F. Speranza, R. De Rosa, P. Donato, and M. Sonnino
(2010), A buried volcano in the Calabrian Arc (Italy) revealed by high‐resolution aeromagnetic data, J. Geophys. Res., 115,
B11101, doi:10.1029/2009JB007171.
1. Introduction
[2] Aeromagnetic surveying is a relatively new technique for
studying volcanic or active tectonic areas through improve-
ments in data acquisition, GPS measurements, and data‐
processing methods [e.g., Finn et al., 2001; Lenat et al., 2001;
Chiappini et al., 2002; De Ritis et al., 2005]. In volcanic
areas, aeromagnetic surveys allow researchers to decipher
the inner structure of eruptive centers and, in marine environ-
ments, to detect submerged, hidden volcanoes and vents
[Rollin et al., 2000; Blanco‐Montenegro et al., 2007; De
Ritis et al., 2007]. Due to the occurrence of widespread vol-
canic deposits of uncertain origin in southern Calabria (Italy),
particularly in the Capo Vaticano (CV) promontory [De Rosa
et al., 2001, 2008], a recent high‐resolution aeromagnetic
survey has been conducted by the Airborne Geophysics Sci-
ence Team of Istituto Nazionale di Geofisica e Vulcano-
logia (INGV), covering the offshore and onshore areas
between CV and the calc‐alkaline to shoshonitic Stromboli
and Panarea volcanoes of the Aeolian Islands (Figures 1
and 2). Results of the aeromagnetic survey reveal a 25 km
WNW‐ESE elongated magnetic anomaly covering the CV
on land and in offshore areas. This anomaly is noteworthy
to be investigated because of (1) the vicinity of the Aeolian
volcanic Arc, (2) the lack of high‐susceptibility geologic
units outcropping in the CV area, and (3) the presence of
volcanic products of unknown origin outcropping in western
Calabria and mainly on CV. A geological model has been
built on the basis of inverse and forward magnetic models
together with the geotectonic and seismic knowledge of the
area. Inversion of magnetic data set was carried out to define
a 3‐D anomalous susceptibility contrast model. To further
constrain the obtained model, a 2.75‐D forward modeling
was also made that included the lithological and structural
1
Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy.
2
Department of Earth Science, Università della Calabria, Arcavacata di
Rende, Italy.
Copyright 2010 by the American Geophysical Union.
0148‐0227/10/2009JB007171
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2. information of the study area. Rock magnetic properties
have been measured on samples representative of the main
local lithological units. The results highlight the presence of
a previously unknown volcanic body emplaced along the
main fault located at the southern edge of the CV prom-
ontory. This body could represent the source area of the
widespread volcanic deposits exposed in CV and western
Calabria. The results, discussed in light of the available
geological and geophysical information, shed new light on
(1) the tectonics of the Calabrian Arc and (2) the general
control of preexisting structures and, in particular, of trans-
versal structures in subduction setting on the emplacement
of volcanoes.
2. Geodynamic and Geological Setting
2.1. Structure
[3] The Calabrian Arc, Sicilian Maghrebides, and Apen-
nines are mountain belts bounding the southern and eastern
sector of the Tyrrhenian Sea back‐arc basin (Figure 1). The
evolution of the Calabrian Arc and Tyrrhenian Sea back arc
during Neogene and Quaternary periods was driven by the
southeastward retreat of the Ionian slab [Malinverno and
Ryan, 1986; Jolivet and Faccenna, 2000; Faccenna et al.,
2001]. The Calabrian Arc is presently located on the top
of a 200 km wide, subducting slab dipping 70° toward NE
(Figure 1) [Spakman et al., 1993; Chiarabba et al., 2008;
Neri et al., 2009]. Earthquake distribution and seismic tomog-
raphy indicate that the northeastern boundary of the sub-
ducting slab roughly corresponds on the surface to the
boundary between southern Apennines and Calabrian Arc
[Chiarabba et al., 2008, and references therein]. The western
boundary of the slab occurs in correspondence of the NNW‐
SSE‐striking Tindari‐Letojanni fault system, which crosses
the eastern margin of Sicily (Figure 1) [Barberi et al., 1994;
De Astis et al., 2003]. This fault system constitutes the
northern extent of the Malta Escarpment, which represents a
transtensional (right‐lateral) transfer zone between the con-
tinental crust of eastern Sicily (west) and the oceanic Ionian
basin (east) [Doglioni et al., 2001, and references therein].
The Malta Escarpment transfer zone, along which the Mt.
Etna volcano is emplaced, is characterized by vertical slip‐
rates of up to 2 mm/yr [Azzaro et al., 2000]; its movement is
related to the larger retreat of the subduction hinge in the
Ionian Sea with respect to the Sicily mainland.
[4] The Aeolian Arc, which forms a ring‐like chain of
volcanic islands and seamounts in the southern margin of
the southern Tyrrhenian Sea oceanic basin (Marsili basin)
[Nicolosi et al., 2006], formed during the last 1 Myr, and
the volcanoes of Lipari, Vulcano, Panarea, and Stromboli
Figure 1. Tectonic scheme of Italy (modified from Chiarabba et al. [2008]; Rosenbaum et al. [2008]).
Dashed lines with numbers identify the depth of the slab below the Calabrian Arc as deduced from
seismic data. TL, the Tindari‐Letojianni fault system; ME, the Malta Escarpment. Lines with triangles
indicate reverse faults; lines with perpendicular marks indicate normal faults.
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3. are still active today (Figure 2a). The evolution of the
Aeolian volcanism, which includes calc‐alkaline to shosh-
onitic and K‐alkaline products, has been related to both
the subduction of the Ionian lithosphere [Chiarabba et al.,
2008] and a postcollisional, rift‐type volcanism associated
with the extensional tectonics that have affected the Calab-
rian Arc in last 1–0.7 Myr [De Astis et al., 2003, and refer-
ences therein]. Recently, Rosenbaum et al. [2008] also
proposed that slab tear faults, which reflect the segmentation
of the Apennines–Calabrian Arc–Tyrrhenian Sea subduction,
control the emplacement of some Quaternary volcanoes and
identify, in the Aeolian Islands–Calabrian Arc region, the
Tindari‐Letojanni fault system as one of these slab tear faults
(Figure 1). The internal structure and recent tectonics of the
Calabria block is debated, and two main end‐member models
have been proposed in the last years: (1) Calabria is frag-
mented into several blocks undergoing differential displace-
ments toward the trench and separated by NW‐SE striking
faults [Knott and Turco, 1991; Van Dijk, 1994; Guarnieri,
2006; Tansi et al., 2007; Del Ben et al., 2008]; (2) alterna-
tively, the Calabria block is solely characterized by exten-
sional faulting, as syn‐sedimentary extensional features are
documented in the whole middle to upper Miocene to Pleis-
tocene sedimentary succession [Mattei et al., 1999, 2002;
Monaco and Tortorici, 2000; Cifelli et al., 2007a, 2007b].
[5] The Calabrian Fore‐arc basin (CFB), located in the
central‐southern sector of the Calabrian Arc, is composed
by several NE‐SW elongated basins fed by sediments
derived from Serre, Poro, and Aspromonte crystalline Mas-
sifs (Figure 2b). The geometry of these basins is controlled
by late Pliocene–Holocene NE‐SW and minor NW‐SE
striking faults. CFB consists of different allochthonous struc-
tural units (Figure 2b). A continuous crustal section from
granulite grade through granitoids and amphibolite‐facies
gneisses into unmetamorphosed Paleozoic and younger
sediments crop out in the Serre Massif [Schenk, 1984, 1990;
Amodio Morelli et al., 1976]. The granulite‐facies is over-
lain by gneiss and paragneiss with granofels and siliceous
marble (Polia‐Copanello unit). In the middle sector of the
Serre and Poro Massifs, granitoids crop out over an area of
about 1250 km2
. The granitoids overlie the Polia‐Copanello
unit and intrude into the overlying ortho‐ and paragneisses
(Aspromonte unit) and lower‐grade Paleozoic rocks (Stilo
unit) [Schenk, 1984; Ayuso et al., 1994; Graessner and Schenk,
2001; Caggianelli and Prosser, 2002]. Along the south-
eastern side of the Serre Massif, the granites come into
contact with Mammola and Pazzano complexes [Colonna
et al., 1973], which are made up by micaschists and para-
gneisses with interbedded Ordovician tholeiitic metabasalts
[Acquafredda et al., 1994]. The Pazzano complex consists
of phyllites, with interbedded graywackes and marbles
[Bouillin et al., 1984, 1987; Acquafredda et al., 1987, 1989].
A Mesozoic sequence made up of dolostone, calcirudite and
calcarenite, breccia, and reef limestone [Roda, 1965; Bonardi
et al., 1984] lies on the Stilo–Pazzano and Mammola com-
plexes. Along the Ionian coast of Calabria, a succession
of latest Chattian–Quaternary age rocks [Patterson et al.,
1995] overlies the Stilo unit and Mesozoic carbonates. The
Stilo–Capo d’Orlando formation is composed of red con-
glomerate, sandstone, and pelites [Cavazza, 1989; Cavazza
and DeCelles, 1993]. The unit is conformably overlain by
a chaotic melange of pelitic matrix that encloses olistoliths
of calciturbidites and Chattian–early Miocene quartzarenitic
turbidites [Cavazza et al., 1997; Bonardi et al., 2001].
[6] The Serravallian–Tortonian sedimentary sequence con-
sists of continental conglomerate, marine sandstone, marl,
and shale, as well as minor shales, Messinian limestone,
and gypsum. This unit is overlain by alluvial conglomerate and
discontinuous shallow‐marine to continental sandstone and
pelite. The upper portion of the basin filling is represented by
marls of the Trubi formation overlain by shallow‐marine and
transitional‐continental facies of late Pliocene–Quaternary age.
Figure 2. (a) Location of the Capo Vaticano ridge. (b) Geological map of southern Calabria showing
outcrops of the volcaniclastic deposits (stars) and WNW‐ESE geological section (profile A‐B). The
bathymetry of the Capo Vaticano ridge is reported along with offshore active faults [data are from
Cifelli et al., 2007a; De Rosa et al., 2008; Tortorici et al., 2003; and Milia et al., 2009). (c) Southern
Calabria and northeastern Sicily magnetic anomaly field sketch map from Caratori Tontini et al. [2004].
The black dotted line is the geological profile shown in Figure 2b.
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4. Figure
2.
(continued)
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5. [7] Several orders of marine terraces distributed from
about 50 up to 1,000 m above sea level (asl) indicate an
uplift of the southern and western sectors of Calabria from
lower to middle Pleistocene times [Ghisetti, 1981; Dumas et
al., 1982; Mulargia et al., 1984; Westaway, 1993; Miyauchi
et al., 1994; Tortorici et al., 1995; Antonioli et al., 2006].
The estimated uplift velocity is generally between 1.0 and
2.1 mm/yr in the last 124 kyr. In the CV area, however, the
uplift velocity has reached 4.0 mm/yr [Westaway, 1993;
Miyauchi et al., 1994]. Westaway [1993] estimated an uplift
velocity of the Calabria area of 1 mm/yr for the last 0.9 Myr.
Normal, active faults trending WNW or NE affect the onshore
Figure 2. (continued)
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6. and offshore sectors of the CV promontory. A major WNW‐
ESE fault shows late Quaternary slip‐rates of up to 2.5 mm/yr
and is responsible for the northeastward tilting of the CV
promontory (Figure 2b) [Tortorici et al., 2003]. This fault
also controls the morphology of the CV southern coastline
and its offshore sector. The CV offshore is characterized by
a WNW‐ESE elongated ridge with a flat, subcircular trun-
cated top at 200 m below sea level (bsl) (Figure 2b). A
seismic profile crossing the northern flank of the ridge
evidences a chaotic basement covered by a thin succession
of sediments younger than 0.7 Myr [Milia et al., 2009].
Tomographic studies [Barberi et al., 2004] reveal the
occurrence of a subcircular body located between 0 and
5 km depth with Vp/Vs values (1.8) higher than those of the
surrounding areas (Vp/Vs < 1.6–1.7). This body is centered
on the CV morphological ridge.
2.2. Volcaniclastic Sedimentation in the Calabria
Fore‐Arc Basins
[8] The CFB and CV sedimentary evolution is charac-
terized by an important middle Pleistocene volcanic and
volcaniclastic input. Volcaniclastic deposits consist of iso-
lated pumice swarms, ash layers, and thick pumiceous lapilli
sequences occurring as distinct lithofacies within sedimen-
tary successions of shallow marine environments [De Rosa
et al., 2001]. According to De Rosa et al. [2008], these
sequences have the characteristics of proximal tephra fall
deposits from Plinian columns reworked in shore environ-
ments. In the Mesima basin and Gioaia Tauro plain, the
deposits have reached 6 and 21 m in thickness, respectively
(Figure 2b). In the CV area, the occurrence of impact sags in
the volcanic deposits attests the proximity of the vent area.
The compositional homogeneity of fragments (calc‐alkaline
dacites and rhyolites) and the lack of nonvolcanic detritus,
soils, or organic matter indicate that the deposits were
quickly reworked after their primary emplacements [De
Rosa et al., 2001, 2008]. K‐Ar determinations of the glass
from the pumices give ages in the range 0.67–1.07 Myr
[Cornette et al., 1987]. The mineralogical assemblage and
the trace element geochemistry of the pumices are consistent
with a provenance from magmatic‐arc volcanism [De Rosa
et al., 2008]. The decrease in the maximum size of pumice
from Mesima basin‐CV area to the Gioia Tauro plain and
Reggio Calabria basin (Figure 2b) and the presence of lithics
of lavas suggest a provenance from a source located off-
shore, not far from the present CV promontory [De Rosa
et al., 2001, 2008]. De Rosa et al. [2008] propose two
hypotheses for the source areas of the pumice deposits of
CFB and CV:
[9] 1. A provenance from Panarea Island (Aeolian Arc)
during an early highly explosive phase, leading to the col-
lapse of the summit of the first edifice. This hypothesis
remains to be confirmed and does not agree with the lack of
rhyodacitic, pumiceous deposits on other Aeolian terrains
with age >100 kyr. In addition, the occurrence of impact
sags in the CV deposits [De Rosa et al., 2001] is not con-
sistent with a source located at a distance of about 70 km
(i.e., the distance between Panarea and the CV promontory).
[10] 2. The tephra falls are related to the explosive activity
of a “buried” calc‐alkaline volcano located in the Tyr-
rhenian Sea. According to De Rosa et al. [2001, 2008], the
CV pumice deposits could represent the only evidence of a
large explosive eruption in the southern Tyrrhenian Sea, the
very proximal equivalent of which is not preserved.
3. Regional Magnetic Anomaly Field
[11] To get a reliable interpretation of the CV magnetic
anomaly system, it is necessary to arrange the study area in
the frame of the regional knowledge described in section 2.
Geologic and magnetic field maps [Agip, 1981; Chiappini
et al., 2000; Caratori Tontini et al., 2004; Finetti, 2005]
provide a general outline of the geostructural characteristics
and long‐wavelength magnetic anomalies (Figure 2c) of
southern Calabria and the southern Tyrrhenian Sea. Fifty
kilometers west of the CV, the Aeolian Arc (Panarea Island
and Lamentini seamount; Figure 2a) is set up by strongly
magnetic Holocene–Pleistocene volcanics [Zanella, 1995]
overlying the barely magnetic units of the Calabrian Arc
[Barberi et al., 1994]. Consistently, this western region is
characterized by high‐intensity positive magnetic anoma-
lies corresponding to the volcanic islands and seamounts
[Chiappini et al., 2000; De Ritis et al., 2005]. Eastward,
the Calabride units [Schenk, 1990], characterized by low to
null magnetic anomaly values, are exposed in the CV and
Le Serre horsts and in the Mesima graben (Figure 2b).
Westward, in the CV offshore sector, the Calabrian units are
intensely faulted and lowered by normal faults, which have
produced the nearby Paola and Gioia Tauro sedimentary
basins. These depressions are filled with as much as 5,000 m
of middle Miocene to Pleistocene sedimentary sequences
that can be considered of low susceptibility, according to
measurements carried out on similar sediments exposed
elsewhere in Italy [Sagnotti et al., 1998]. In fact, in this sector,
marine terrigenous series above the Calabrian metamorphic
units have been interpreted through seismic profiles and dril-
lings starting from the Serravallian age [Milia et al., 2009]. A
wide region characterized by low to negative values of the
magnetic anomaly field exists as a result of this regional
setting (Figure 2c). It extends from the Stromboli canyon to
the Ionian Sea (E‐W) and from the Messina Strait to the
Catanzaro plain (N‐S).
[12] Toward North and Northeast, two long‐wavelength,
low‐intensity linear positive anomalies develop parallel to the
main regional tectonic features of the Catena Costiera and
Sila (Figure 2c) [Van Dijk and Okkes, 1991]. The anomalies
express the presence of contrasts characterized by very low
magnetization values of the Calabrian Arc units.
[13] Southward, the Etna long‐wavelength magnetic anom-
aly negative lobe contributes to lowering of the regional
magnetic anomalies field (Figure 2c). Negative lobes of other
high‐intensity magnetic anomalies lying in the Stromboli
canyon affect the CV magnetic anomaly system. By means
of synthetic models, we estimated the total entity of this
magnetic anomaly lowering to be in the range of 15–20 nT.
[14] The CV high‐intensity positive magnetic anomaly
(Figures 2c, 3a, and 3b) lies in correspondence of the CV
morphological ridge (Figure 2b), highlighting the presence
of a noticeable magnetization contrast in an area strongly
affected by tectonic structures.
[15] Because of the lack of susceptibility measurements
available in the literature for the Calabrian Arc, we carried
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7. out sampling of the main lithological units of the area. Then,
we measured rock sample susceptibility in the paleomag-
netic laboratory of INGV (Rome) to get reliable modeling
and effective interpretation of magnetic anomalies. In addi-
tion, because crustal magnetic anomalies are originated by
3‐D variations of rock properties at depth, we reconstructed
the stratigraphic sequence reported in the geological pro-
file of Figure 2b and sampled the most representative and
widespread lithologies of the region. Southern Calabrian
structures, from the Ionian to the Tyrrhenian sides (NW‐SE
direction), are composed by conglomerates, sandstones, and
clays of the Calabride units (Tortonian to lower Pliocene),
granites, granodiorites, and tonalities of the Aspromonte
Peloritani units (Permian–Carboniferous), and terrigenous
marine deposits and calcarenites lower Messinian to lower
Pleistocene in age. The CV promontory, in particular, is
made up by intrusive igneous rocks and terrigenous marine
deposits (Figure 2b). Therefore, it is reasonable to infer that
these units are the representative bedrock of the offshore
study area, possibly lowered by the action of faults and
covered by middle Miocene–Holocene sediments [Milia
et al., 2009; Mattei et al., 2002].
[16] Mass susceptibilities of rock samples were measured
at the INGV paleomagnetic laboratory of Rome. Subse-
quently, volume susceptibilities were calculated by consid-
ering average rock density values available in the literature
(Table 1). Volume susceptibilities were determined for a
total of 24 samples including 11 sedimentary samples of
sandstone, sand, carbonate, and clay successions belonging
to terrigenous marine deposits and marine terraces; 9 sam-
ples of the metamorphic and plutonic complex such as the
granites and phyllades of Le Serreand Mesima units; 3 vol-
canic samples set up by pumices with different granulo-
metries deriving from outcrops lying in the CV area, in the
Gioia Tauro basin, and in the Mesima graben (Figure 2b);
and 1 sample of metagabbro from an Oligocene shear zone
separating nappes of the Hercinian basement [Langone
et al., 2006].
[17] The sedimentary and metamorphic/plutonic speci-
mens show very low volume susceptibility values (10−6
up
Figure 3. (a) Total intensity magnetic anomalies of the Capo Vaticano (CV) and offshore areas. Dotted
lines mark the Calabria coast line. Inset in Figure 3a represents the aeromagnetic survey flight lines
(black) and the tie lines (red). (b) Reduced‐to‐the‐pole magnetic anomaly field assuming geomagnetic
inclination of 90° and declination of 0°; the dotted red lines refer to the AB and CD magnetic profiles
reported in Figures 5a and 5b. The main anomalies are highlighted with numbers from 1 to 5.
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8. to 10−4
SI) (Table 1). The volcanic samples also exhibit
low susceptibility (10−4
SI), probably because of their high
silica content and clastic fabric. Our measurements are
consistent with those summarized in Barberi et al. [1994],
who report susceptibilities of the Calabrian Arc rocks less
than 7 × 10−7
SI. An isolated exception is our metagabbro
sample, which has a susceptibility value as high as 10−2
SI.
However, this lithology forms small (decimetric to metric)
lenses corresponding to a low‐intensity, long‐wavelength
magnetic anomaly developing 15 km northwest of CV. We
have not measured the magnetic remanence of the Calabrian
Arc rocks because the rock susceptibility values are gener-
ally very low, implying a very poor content of magnetite and
thus negligible magnetic remanence. In addition, the rocks
are Meso‐Cenozoic in age and are arranged in a chaotic
tectonic setting with the result that their polarity will be
mixed, and the reconstruction of the rock volumes with
constant magnetic polarity it is not possible. The measure of
remanence of these rocks has no practical bearings. More-
over, in situ samples of the CV volcanics are also lacking
and the on‐land outcropping pumices, which have been
reworked in shallow marine environments, show SI values
in the order of 10−4
(see Table 1), suggesting low magnetic
attitude. In conclusion, the CV positive magnetic anomaly
system represents a clear contrast between an unknown
magnetic source and the virtually nonmagnetic rocks of the
Calabrian Arc.
4. Data Acquisition and Processing
[18] A high‐resolution aeromagnetic survey was recently
carried out by the Airborne Geophysics Science Team of
INGV for a detailed characterization of the offshore–onshore
CV anomaly field. Thirty‐four measurement profiles were
flown in the N‐S direction across the CV morphological
ridge with a line spacing of about 2 km apart (Figure 3a,
inset). Tie lines were also flown in the E‐W direction to
level the survey lines. The survey area extends from the
Mesima graben to the Panarea and Stromboli eastern marine
areas. In the offshore sectors, the survey was flown at con-
stant barometric height (500 m), whereas the profiles cross-
ing the CV promontory were draped, reaching a maximum
flight altitude of 1000 m. Total intensity anomaly data were
acquired with an optically pumped cesium magnetometer at
the sampling rate of 10 Hz. A GPS receiver in differential
Figure 3. (continued)
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9. mode was used for accurate survey navigation, and a laser
altimeter recorded the flight altitude.
[19] We performed the reduction of the aeromagnetic data
by removing the effects of the time‐varying external fields
and computed the anomalies obtained by removing the
Geomagnetic Reference Field [IAGA, 2005]. To produce the
total intensity magnetic anomaly map, the data sets were
merged and gridded at the spacing of 1,000 m by using
a minimum curvature algorithm. Finally, the data set was
microleveled to remove a few residual errors from the
gridded data; the field obtained is shown in Figure 3a.
[20] To facilitate the forward modeling and its geological
interpretation (see section 5.2), the total field anomalies
have been reduced‐to‐pole (RTP) [Baranov and Naudy,
1964]. This analytical transformation sets the magnetic
anomalies above their relative sources and transforms each
dipolar anomaly into positive or negative. This has the
advantage of considerably simplifying the magnetic mod-
eling because the magnetic contacts in the model would
thus not be substantially far from the real position. As a
consequence, the relation between anomaly and source in
the map is more evident. Using the RTP algorithm, we have
assumed that the ambient magnetic field and the magneti-
zation have constant directions along the studied area. The
smaller the area, the more valid is this assumption. For the
70 × 55 km coverage of this survey, we are confident that
this assumption holds. The RTP magnetic anomaly map is
shown in Figure 3b. A WNW‐ESE elongated positive
anomaly characterizes the CV area (anomaly 1 in Figure 3).
However, a negative anomaly also appears south of the CV
anomaly 1 in the RTP map (Figure 3b). Because this neg-
ative feature overlaps the CV WNW‐trending fault (see
Figure 2), we investigated its characteristics and meaning
(see section 5.2).
5. Magnetic Modeling
[21] The final goal of potential field surveys is to get
quantitative information about the causative sources and to
interpret them in the frame of the geological knowledge of
the area. Here, we have chosen to carry out both inverse and
direct approaches. To build a reliable 3‐D geological model
of the subsurface CV structure, aeromagnetic data have the
fundamental role of providing a quantitative constraint on
the distribution of the susceptibility rock properties on a
wide offshore area that is otherwise not directly accessible.
Table 1. Summary of Rock Magnetic Properties Measured in Calabria in the Areas of Capo Vaticano, Mesima Graben, and Le Serre
Chain Along With the Sample Description and Geographic Position
Sample Latitude Longitude Lithology Description Location
Volume
Susceptibility
(SI)
Sedimentarian
Units
1 38°33′24″ 16°07′37″ Sandstone Pleistocenic seabord coarse
silicocalstic sandstone
Mesima graben,
Marepotamo valley
−9.51 × 10−6
2 38°39′16″ 15°50′46″ Sandstone Tortonian medium to coarse
silicocalstic sandstone
Mt. Poro‐Capo Vaticano 1.22 × 10−5
3 38°33′27″ 16°07′42″ Sand Fine sand Mesima graben,
Marepotamo valley
1.20 × 10−4
4 38°38′16″ 15°54′00″ Carbonates Messinian carbonates and
marly carbonates
Mt. Poro ‐ Spilinga 8.79 × 10−5
5 38°23′19″ 16°23′52″ Sandstone Medium to lower Miocene
banded sandstone, turbidites sequence
Westward Caulonia village 1.54 × 10−4
6 38°33′29″ 16°06′42″ Clays Marly and silty clay succession Mesima basin 4.37 × 10−5
7 38°23′12″ 16°23′59″ Sandstone Lower Miocene silicocalstic sandstone Westward Caulonia village 5.76 × 10−5
8 38°22′29″ 16°24′58″ Sand Lower Pliocene sand Le Serre chain, western side,
Caulonia village
7.71 × 10−5
10 38°22′27″ 16°25′48″ Clays “Varicolori” clay; red, green, and
gray clay succession
Le Serre chain, western side,
Caulonia village
1.39 × 10−4
23 38°39′27″ 15°56′32″ Sands Quaternari marine terraces sands Spilunga‐Zungari 1.54 × 10−5
19 38°22′27″ 16°25′48″ Clays Varicolori clays: numidic olistonites Caulonia 9.97 × 10−5
Metamorphic and
Plutonic Units
9 38°25′16″ 16°22′31″ Phyllade Metamorphic complex
(from metarenites to paragneiss)
F.va Allaro 1.33 × 10−4
11 38°37′06″ 15°48′44″ Dark granite Melanocratic facies granite Capo Vaticano 1.34 × 10−4
12 38°37′06″ 15°48′44″ Bright granite Leucocratic facies granite Capo Vaticano 1.9 × 10−4
13 38°31′15″ 16°08′28″ Granite Le Serre chain, western side 1.04 × 10−4
14 38°25′16″ 16°22′31″ Phyllade Metamorphic complex
(from metarenites to paragneiss)
F. va Allaro 2.38 × 10−4
15 38°23′37″ 16°23′10″ Phyllade Gray phyllade Le Serre eastern side,
Popolli‐Serra Schiavella
1.60 × 10−4
16 38°24′57″ 16°21′33″ Granite–aplite Aplitic sills inside Le Serre granites F. va Allaro 6.95 × 10−6
17 38°24′57″ 16°21′33″ Granite F. va Allaro 1.30 × 10−4
18 38°31′15″ 16°08′28″ Granite Le Serre chain, western side 4.50 × 10−4
24 38°49′18″ 16°17′51″ Metagabbro Curinga 1.10 × 10−2
Volcanic Units
20 38°37′28″ 16°06′29″ Pumice Granulometry: 1 mm 1.66 × 10−4
21 38°37′28″ 16°06′29″ Pumice Granulometry: 4 mm 2.34 × 10−4
22 38°37′28″ 16°06′29″ Pumice Granulometry: 8 mm 2.28 × 10−4
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10. As a first‐order of approximation, lithology controls mag-
netic properties through its mineralogy, and abrupt variation
in rock properties may highlight lithological contacts. Since
the backbone of southern Calabria is mainly composed of
nonmagnetic rocks (see section 3), the presence of the CV
positive magnetic anomaly allows us to infer the presence of
a magnetized body not related to the surrounding exposed
units. To get a more reliable interpretation of the CV
anomaly system causative bodies, we carried out data inver-
sion, obtaining the representative magnetization value, shape,
depth, and horizontal extent of the body. Furthermore, a
2.75‐D forward model has been carried out with the aim of
adding further geostructural constraints to the inversion
results by using measured susceptibility values for the back-
ground rock properties (Table 1). The CV anomaly system
shows a simple pattern lightly affected by the regional field,
which influences the intensities of the short‐wavelength
components (anomalies 2, 3, and 4 in Figure 3). The regional
field is not completely sampled due to the shorter dimension
of the surveyed area, and it is characterized by the over-
lapping effects of sources lying in south Calabria (e.g., in the
Catena Costiera and Sila areas) (Figure 3). The influence of
such sources is not homogeneous and difficult to evaluate
using analytical methods.
5.1. Inversion Modeling
[22] We applied a 3‐D inversion approach to the magnetic
anomaly data of the CV area with the aim of modeling the
subsurface bodies generating the observed anomaly. As is
well known, the mathematical inversion approach is defined
as the quantitative estimation of some models parameters
starting from their effect (e.g., magnetic measures), knowing
the mathematical relationship that links the models para-
meters with their spatial effect (forward problem). From a
mathematical point of view, the inversion applied to surface
potential data field is an ill‐posed problem that suffers from
instability and algebraic ambiguity of solutions [Blakely,
1995], so that model parameters are not analytically invert-
ible from anomaly data. A common procedure to reduce those
ambiguities and obtain realistic geological sources is the
introduction of additional information in the form of a priori
geological data or mathematical regularization. A common
approach to solve these kinds of problems in potential fields
inversion is to divide the subsoil, where the real geological
source is supposed to be located (a priori information), into
a number of homogeneous magnetized rectangular blocks
(cells) for which the direction of magnetization is supposed
to be known and equal for each block. Such “discretization”
defines the exact geometry of each single subsurface cell so
that it is possible to generate the observed potential field
measurement by applying an appropriate magnetization
value for each cell [Bear et al., 1995]. In this form, the
inversion problem is linearized so that the unknown
parameter to be determined is the magnetization module of
each cell. In our analysis, we adopted the forward solution
following Sharma [1986]. Considering the vector of spatial
measures b and the magnetization vector x of N cells, the
linear forward model evaluating the effect of the whole cells
on ith station point is expressed by
bi ¼
X
N
j¼1
Aij xj;
where j is the cells index, Aij is the sensitivity matrix
coefficient that evaluates the contribution on the ith station
point of the jth cell, considering unitary magnetization. To
resolve this linear system in the x vector unknowns, we
adopted the iterative regularization minimization method of
Levenberg and Marquardt [Press et al., 1992]. This method
simultaneously minimizes the norm of the solution and the
misfit between the observed and the computed synthetic
magnetic anomalies generated by the magnetization solution
vector. We also applied a positivity control on the magne-
tization solution because of the CV positive dipolar anomaly
geometry.
[23] Taking into account the spatial extent of the CV mag-
netic anomaly (Figures 2b and 3), we built a 3‐D block mesh
made with cells of dimensions 2,000 m E × 2,000 m N ×
500 m below the surface. The maximum depth is at 3,500 m.
The inversion setup corresponds to a total number of
3,600 cells. We adopted a regular measure grid made by
2,000 m spaced nodes calculated by gridding the original
magnetic data. To stabilize the inversion model results, we
used the same dimensions for the block cells mesh and the
measured grid. In calculating the sensitivity matrix, it is
necessary to define the vector values of block magnetiza-
tion; we assume that the total magnetization vector of the
CV body is subparallel to the Total Magnetic Field direc-
tion and hence apply a magnetic inclination of 55° and a
declination of 0°. To better constrain the resulting model,
we defined a bathymetric surface (data from Tortorici et al.
[2003]) above which cells were not used in the inversion
calculation.
[24] Figure 4a shows the resulting model from inversion
procedure applied to the magnetic anomaly data, Figure 4b
shows the measured magnetic data used in inversion pro-
cess, and Figure 4c shows the synthetic anomaly map. The
differences between the synthetic and observed data are
reported in Figure 4d. The CV anomaly is well recovered by
the inversion model. However, regional longer wavelengths
extend well beyond the relatively limited survey area, as
shown on the regional anomaly map in Figure 2c [Caratori
Tontini et al., 2004], and the inversion approach cannot
resolve this problem. The occurrence of such long‐wavelength
anomalies could cause a misfit between the measured mag-
netic anomaly data and the synthetic anomaly values gener-
ated by the recovered inversion model. Taking into account
Figure 4. (a) Magnetic source model from inversion process obtained from the sea level down to 3,000 m below sea level;
distances are expressed in meters. (b) Observed magnetic anomaly data. (c) Synthetic anomaly map obtained for the mag-
netization distribution shown with I = 54° and D = 2° inducing field. (d) Differences between synthetic and observed data
shown in Figures 4b and 4c. (e) Field (in color) generated by the susceptibility model in Figure 4a with a I = 90° and D = 0°
inducing field (the synthetic magnetic effect that this source model would have at the magnetic North Pole). The RTP field
of real data of Figure 3b is reported as isoline contouring.
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11. Figure 4
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12. this possible misfit, we focused on the fitting quality of the
CV anomaly. The differences between the synthetic and
observed data (Figure 4d) show a long‐wavelength misfit
trend oriented N‐NE, S‐SW with amplitude between 0 and
−10 nT (about 5% of the maximum amplitude of the CV
anomaly). In the surrounding area, the misfit shows a clear
long‐wavelength pattern with amplitude oscillating between
−20 and −10 nT. The inversion does not well describe the
east side of the inversion area because of the positive
magnetic anomalies generated by geological sources located
in Calabria. This misfit is described in Figure 4d by negative
anomalies with a minimum of −40 nT in a very limited area
in the eastern side of the map. The above summarized misfit
values are very low, thus suggesting the goodness and
Figure 4. (continued)
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13. reliability of the inversion model. The recovered inversion
model reported in Figure 4a describes a positive magnetic
body approximately 20–25 km long WNW‐ESE striking
with maximum magnetization values of 1.5 A/m.
[25] We carried out a further model to investigate the
nature of the RTP negative anomaly appearing just to the
south of positive anomaly 1 (Figure 3b). This negative
anomaly represents an interesting issue to investigate, since
it precisely overlaps the offshore prolongation of the CV
fault. We computed the field generated by the susceptibility
model of Figure 4a with a I = 90° and D = 0°–inducing field
(the synthetic magnetic effect that this source model would
have at the magnetic North Pole). The results are shown as a
color map in Figure 4e, where the RTP field of real data
(Figure 3b) is also reported as isoline contouring. The close
matching of these two fields indicates that the negative
feature depicted in the RTP map of Figure 3b results from
the RTP computation [see also Silva, 1986] and belongs to
the anomaly 1 source recomputed at the North Magnetic
Pole.
5.2. Forward Modeling
[26] We carried out the forward modeling along two key
profiles crossing the area in the WNW‐ESE and NNE‐SSW
directions (Figures 3b and 5). The measured rock suscepti-
bility values (Table 1) were used to characterize the exposed
and deep stratigraphic sequences shown in the geological
profile (Figure 2b). Tectonic units depicted in the sections
are taken from the structural model of Italy [Finetti, 2005].
The modeled body (position, geometry, and extension) was
drawn on the basis of the inversion results. In both profiles
shown in Figure 5, the structures were further constrained
with the available surface geology information. In addition,
the uppermost crust beneath the CV morphological ridge
was constrained with the seismic profiles crossing the area
[Trincardi et al., 1987; Milia et al., 2009]. The extension of
the modeled bodies along the profiles are reported in Table 2.
[27] The A‐B profile (Figure 5) was chosen with the goal
of crossing symmetrically the CV anomaly along its major
axis and sampling its intensity peak. The C‐D profile was
oriented orthogonally to the previous one. This profile was
chosen to further constrain the modeling and to interpret the
low‐intensity, short‐wavelength anomalies lying southward
of the CV fault and not imaged by the inversion results
(Figure 5). In fact, our high‐resolution, near‐surface survey
has also detected the higher‐frequency components in the
anomaly field that were not visible in the previous magnetic
surveys [Agip, 1981; Chiappini et al., 2000; Caratori
Tontini et al., 2004]. These minor magnetic signatures are
here interpreted in the same framework of the CV anomaly
causative body and, for this reason, are called the CV
magnetic anomaly system. We achieved the modeling by
using an implementation of a 2.75‐D forward modeling
found on the expressions of Talwani and Heirtzler [1964],
Rasmussen and Pedersen [1979] and on the algorithm
proposed by Won and Bevis [1987]. The proposed models,
summarized in Figure 5, are discussed in section 6.
6. Discussion and Conclusion
[28] The results of the magnetic modeling highlight the
occurrence of a WNW‐trending magnetized body about
20 km long (Figures 4 and 5). This body, which is directly
magnetized, extends from the seafloor to about 3 km bsl,
and intrudes toward ESE, between the CV granites and the
underlying granulites of the Calabrian Arc. The WNW flank
of the body is covered by sediments that, on the basis of
available seismic profiles, consist of sands and silts younger
than 0.7 Myr [Milia et al., 2009]. According to the models
shown in Figures 4 and 5, the width is between 3.5 and
5 km. The reconstructed geometry is consistent with that
of a semitabular, flat, elongated sill. Less extended, 2 to
3 km wide, laccolith‐like highly magnetized bodies also
occur between 3 and 4 km of depth. These minor bodies are
intruded within the granulites of the Calabrian Arc. The
magnetization values needed to explain the observed anoma-
lies in the CV area are between 0.7 and 1.5 A/m (Figures 4
and 5). This magnetization range encompasses that mea-
sured in the evolved rocks (rhyolites and trachytes) of the
Aeolian Islands (0.6–1.6 A/m) [Blanco‐Montenegro et al.,
2007, and references therein]. The collected magnetic data
show that the CV anomaly reaches magnetic anomaly values
(150–220 nT, Figure 3b) that are significantly higher than
those observed in the rest of Calabria (30–50 nT) [Agip,
1981; Caratori Tontini et al., 2004]. In addition, the CV
magnetic anomaly values are of the same magnitude as
those of Panarea Island, Lametini Seamount, Alcione Sea-
mount, and Stromboli canyon, where volcanic rocks outcrop
and have been dragged [Caratori Tontini et al., 2004;
Finetti, 2005]. The anomaly of the Stromboli canyon, which
is located 20 km eastward from Panarea Island, is also
visible in the westernmost side of the CV area survey
(anomaly 5 in Figure 3). The magnetic signature of the CV
promontory turns out to be completely different from the
magnetic pattern of the Calabrian Arc region for both inten-
sity and shape.
[29] The inverse model (Figure 4a) depicts a crustal vol-
ume with an increase of the magnetization (values 0.9 A/m)
in correspondence of the top of the CV bathymetric ridge.
We propose that this 5–6 km long and about 2–3 km wide
rock volume with higher magnetization is representative of
the shallower portion of the plumbing system of the volcano
from which WNW‐ESE elongated apophyses with lower
magnetization depart, probably representing dikes. Besides,
the forward model (Figure 5), which is characterized by a
constant magnetization of the represented bodies, requires a
vertical extension in correspondence to the abovementioned
bathymetric ridge. Both models are able to fit the observed
data correctly, represent two possible settings of the mag-
netization, and be coherent with the occurrence of a volcanic
body. In the first case (Figure 4), the higher magnetization
represents the plumbing systems zone, as reported above;
in the second one (Figure 5), a vertical extension of the body
is required to correctly fit the data to define the plumbing
system geometrically. Therefore, both models highlight a
magnetized, shallow, sill‐like body, the topographic expres-
sion of which is represented by the CV morphological ridge
(Figures 4 and 5). In fact, the results reveal that the apex of
the sill overlaps the subcircular truncated top of the CV ridge
located at a 200 m bsl (Figure 2b). As result of the above
observations, the CV sill could be interpreted as the remnant
of a shallow magmatic body characterized by a central plug
roughly extending to a depth between 500 and 1500 m bsl,
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14. Figure 5. Crustal 2.75‐D magnetic models for profiles crossing the CV anomaly in (a) WNW‐ESE direction, A‐B profile;
(b) N20°E direction, C‐D profile. The trace of profiles is shown in Figure 3b (dotted red lines). Numbers identify marked
anomalies in the reduced‐to‐the‐pole magnetic anomaly field (Figure 3). Faults are indicated by red lines. The size of the
bodies in the direction perpendicular to the profile is reported in Table 2.
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15. Figure
5.
(continued)
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16. and by WNW‐trending minor lens, possibly representing dikes
intruding the Calabrian Arc.
[30] We propose that the CV sill may represent the source
area of the 0.67 to 1.06 Myr old widespread tephra fall
deposits from plinian columns poorly resedimented in shal-
low marine environment outcropping in western Calabria
(section 2.2). The occurrence of (1) maximum thickness of
such deposits in the CV and Mesima areas, (2) progressive
thinning of such deposits toward the southwest (i.e., Reggio
Calabria basin), (3) impact sags related to the emplacement
of ballistic ejecta in the CV area, and (4) sedimentary facies
consistent with a proximal origin for the tephra layers
strongly suggests that the CV magnetic anomaly sector may
correspond to the source area of the middle Pleistocene
volcaniclastic deposits of Calabria [De Rosa et al., 2008].
As a result, the shallow, WNW‐ESE elongated sill depicted
in Figures 4 and 5 is easy to use to represent the shallow
plumbing system of a middle Pleistocene volcano. Such
interpretation is consistent with the occurrence, in the sector
of the CV magnetic anomaly, of a 0–5 km deep, high Vp/Vs
body [Barberi et al., 2004]. The magnetization values
obtained from inversion of the data (Figure 4a) suggest that
the CV sill is composed of rocks with magnetization values
comparable to those of rhyolites and dacites of the Aeolian
Islands [Blanco‐Montenegro et al., 2007]. This consider-
ation corroborates the above interpretation of the CV sill as a
plumbing system of a volcano responsible for the emplace-
ment of the Pleistocene widespread rhyolitic to dacitic
pumices outcropping in Calabria, which show a HK calc‐
alkaline affinity compatible with that of the rocks of the
eastern Panarea sector of the Aeolian Islands [De Rosa et al.,
2008]. On the basis of the stratigraphic, magnetic, and geo-
chronological data, the CV ridge formed before 0.7 Ma,
being partly covered by Pleistocene sediments younger than
0.7 Myr [Milia et al., 2009]. The normal polarity magnetic
signature of the CV body suggests an emplacement during
the Bruhnes (0.78 Ma) [Cande and Kent, 1995; Gradstein
et al., 2005] or Jaramillo (0.99–1.07 Ma) Chrons. On the
other hand, the widespread pumices and volcanic ash layers
outcropping in the studied area deposited in a time inter-
val between 0.67 and 1.07 Ma [Cornette et al., 1987].
Therefore, the CV sill and the Pleistocene volcanics were
emplaced either between 0.67 and 0.78 Ma or between 0.99
and 1.07 Ma. These age intervals roughly overlap the older
ages of Aeolian volcanism, which started between 1.3 Ma
in the western, Alicudi–Filicudi sector and 0.8–0.5 Ma in
the eastern, Stromboli–Panarea sector [De Astis et al.,
2003]. However, the composition of the older dragged
Aeolian rocks is basaltic, whereas the more evolved prod-
ucts, with composition similar to the CV tephra, are younger
than 100 kyr. This indicates that evolved magmas charac-
terized the early, submarine, and possibly explosive, phases
of the Aeolian volcanism. In addition, the rhyolitic and dacitic
composition of the CV Pleistocene magmas volcano, along
with the results of our magnetic modeling, testify to the
formation of sill‐like, shallow magma reservoirs. Accord-
ing to the geometry depicted in Figure 5 and the available
geological data (Figure 2b), the storage depth of such reser-
voirs is controlled by the major discontinuity between the
lower crust granulites of the underlying, Carboniferous–
Permian granites of the upper crust. The shape of the CV
magnetic anomaly clearly shows that the sill geometry has
also been controlled by a WNW‐trending discontinuity. This
is also the strike of the fault affecting the southern coastline
and offshore of the CV promontory (Figure 2). This fault is
possibly seismically active [De Astis et al., 2003] and was
responsible for the destructive 1905 Calabria earthquake,
M = 6.3–6.7, according to Cucci and Tertulliani [2006].
Therefore, we conclude the CV volcano was emplaced on
the footwall of this still active tectonic structure. This feature
is structurally compatible with numerical models of magma
emplacement along active faults [e.g., Ellis and King, 1991;
Pascal and Cloetingh, 2002]. Such models reveal that magma
uprising to the surface along a faulting zone accumulates at
the footwall of a normal fault because the local extensional
strain concentrates at the footwall, whereas a compressive
strain occurs in the hanging wall.
[31] The collected data and the above observations sug-
gest that the recognized CV volcanism is consistent, in
terms of age, magnetic signature, and geochemical affinity
of the erupted products, with that of the Aeolian volcanoes.
The central sector of the Aeolian Arc, which includes the
islands of Salina, Lipari, and Vulcano, develops along a
tectonic structure that it is in a transversal position with
respect to the Aeolian volcanic ring. Our data and inter-
pretation suggest that, indeed, NW‐SE faults (i.e., trans-
versal structures to the general trend of the Calabria block)
must be considered as an important part of the Pleistocene
(and possibly active) tectonics of Calabria. It is also likely
that the seismogenic potential of such structures is at present
underevaluated [Basili et al., 2008] and should be better
assessed.
[32] The WNW‐trending fault that controls the CV
fissural‐like volcano is also transversal to the eastern sector
of the Aeolian volcanoes, which are controlled by NE‐SW
structures. However, this fault does not appear to represent a
slab tear fault [e.g., Chiarabba et al., 2008]. In any case, it
may represents a structure along which magma uprose and
stopped, at least in the last 1–0.7 Ma. In this period, a sig-
nificant (up to 1 mm/yr) uplift affected the Calabria region
and the Aeolian Islands [Westaway, 1993]. The uplift, whose
geodynamic origin is a subject of debate [e.g., Gvirtzman and
Nur, 2001], is maximized in the CV promontory (4 mm/yr
in the last 124 kyr) [Tortorici et al., 2003]. Different uplift
rates of segments of the Calabrian Arc could be responsible
for fragmentation of the upper crust and formation of
transversal faults. As a result, magma emplacement may
Table 2. The Strike of the Structures for the Two Profiles A‐B
and C‐D Is 90°a
Body y1 (km) y2 (km)
Granulites section A‐B 10 10
Sands and sandstone section A‐B 10 10
Granites section A‐B 10 10
Volcanic body section A‐B
Anomaly 1 1.7 1.7
Sands and sandstone section C‐D 10 10
Volcanic body section C‐D
Anomaly 1 5 15
Anomaly 4 3 3
Anomaly 2 3 3
a
y1 is the length toward the west‐northwest in profile A‐B and toward the
N20°E in profile C‐D, whereas y2 is the length toward the east‐southeast in
profile A‐B and toward the N290°E in profile C‐D.
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17. occur along structures like the WNW‐trending fault of the
CV. According to Tortorici et al. [2003], such structures
also act as transfer faults that allow the regional extensional
strain to be transferred from offshore, where it is accom-
modated by the ENW‐WSW trending normal faults, to the
Calabrian Arc, where it is accommodated by NE–SW
trending faults. In this general framework, the composition
of the CV tephra suggest that between 0.67 and 0.97 Ma,
while mafic products were erupting in the Aeolian area,
dacites and rhyolites characterized the explosive activity of
the CV volcano. From a structural point of view, we note
that the CV fissural‐like volcano is similar to the vents of
Lipari and Vulcano islands, which also depict a fissural‐like
structure [De Astis et al., 2003]. As a result, the transversal
faults of the Aeolian Arc appear to control the development
of fissure‐like eruptive centers.
[33] Acknowledgments. This study has been supported with FIRB‐
MUIR and INGV funds. Thanks to numerous colleagues for discussions,
comments, and suggestions. We are grateful to two anonymous referees,
as well as to the Journal of Geophysical Research Associate Editor and
the Editor (Andre Revil) for providing useful comments to our manuscript.
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