Publication Date:
2019-11-14
Description:
The GPS results are of utmost
relevance for the study of the
complex plate boundary
geodynamics.
The lithosphere strain
partitioning is part of the
seismic cycle. We present the
first GPS kinematic pattern
obtained during the
interseismic phase by a dense
episodic GPS network, the
Southern Apennine Geodetic
Network - SAGNet (Sepe et al.,
2009), in the time span
2002-2013.
This network is located across
the transition zone between
central and southern
Apennine, including
Meta-Mainarde-Venafro and
AltoMolise-Sannio-Matese
mounts. This region is
characterized by seismogenic
fault systems responsible, in
the past, for several
destructive earthquakes of
intensity I ≥ IX MCS and, in
more recent years,
characterised mainly by some
moderate magnitude seismic
sequences (max magnitude
Mw 5.0, December 29 2013)
and single small events
(Ml 〈 2.5).SAGNet GPS data were processed by BERNESE sw v.5.0
and the resulting velocities were least-squares combined
with the permanent stations velocity field and with the velocity
solution of Giuliani et al. 2009.
The combined GPS velocity field, shows a perpendicular
maximum extension with respect to the Apennine chain
of about 2.0 mm/y.The Matese area was hit on December 29, 2013 by a Mw=5.0
(Convertito et al., 2016) earthquake. It was followed by an intense
seismic activity until the beginning of February 2014. After the
mainshock a GPS survey was carried out on the SAGnet stations.
We collected data from 2013, 30 December to 2014, 4 April.
The time series of 17 stations are affect by an offsets on the linear
drift. The map of horizontal coseismic displacements (Figure 3)
shows a sub-radial displacement shape with respect to the epicentre.
Larger displacements are observed in correspondence of NE portion of
the Matese massif. Considering the Matese Lake Fault as the probable
source of the mainshock (dip 65°, strike 116, rake 270 – MLF, Ferranti
et al, 2015), we found that the Okada modelling does not fit the
observed displacements and only a small fraction of displacements
are resolved with a simple slip.Figure 4 resembles the results of previous studies compared with our
GPS analysis. We considered seismological analyses, tomographic
models, degassing of CO2 data and conceptual model of processes recognized
in South Apennine (L. Bisio, et al., 2004; Chiarabba and Chiodini,
2013; Improta et al., 2014; Ventura et al., 2007, R. Di Stefano and M.G.
Ciaccio, 2014; Ferranti et al., 2015; Convertito et al., 2016;).
The GPS results indicate that the relative motion between Eurasia and
Adria plates is responsible of the active deformation in the Apennines.
The most important outcomes of this study are: (i) During the interseismic
phase the differential motion between Adriatic and Tyrrhenian domains
seems to be accommodated in a narrow belt bordering the westward
flank of the Sannio Mts, showing a 2 mm/y extension. (ii) The maximum
extension does not follow the topographic high of the chain but is
shifted toward the eastern outer belt. (iii) No significant GPS deformation
is highlighted in correspondence of major and known fault systems
where the GPS velocities appear almost steady.
We propose that the observed coseismic displacements are only marginally
explained by a slip on the MLF fault. The vertical directivity and
depth distribution of the seismic sequence (Convertito et al., 2016),
the vertical and horizontal heterogeneity of lower crust and upper
mantle (Bisio et al., 2004; Di Stefano and Ciaccio, 2014), the high flux
of CO2 degassing (Ventura et al., 2007, Chiarabba e Chiodini, 2013 ),
the probable presence of pressurized CO2 bodies fed by fluids uprising
from the mantle wedge (Improta et al.,2014 ), suggest instead that the
seismic sequence could be caused by sub-vertical cracks that originate
at the Moho interface and reach the bottom of the seismogenic layer
(10km depth).
Description:
DPC
Description:
Unpublished
Description:
San Francisco (USA)
Description:
2T. Tettonica attiva
Description:
open
Keywords:
GPS, Deformation, Active extension
;
04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
Poster session
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