Seismicity and stress field in the Sannio-Matese area

In this study we discuss the available data on seismicity and focal mechanisms in the Sannio-Matese area in order to obtain information on the stress field acting in the area. Background seismicity of the area is characterized by isolated events, with magnitude generally less than 2.5, on which is superimposed a swarm and seismic
sequence activity of low magnitude (max magnitude 4.1). The epicentral distribution of both isolated events and seismic sequences, disclose NE-SW striking active faults that fall in between the fault segments of the large historical earthquakes which occurred in the area. The available information on the stress field deducible from the focal mechanisms of the area agrees that a general extensional stress regime is acting. Locally both NE-SW and NNW-SSE extensions are observed. The large scale stress regime deduced from the focal mechanisms of strong instrumental earthquakes which occurred in the Apennines supports the local NE-SW extension but cannot explain
the normal movements related to a NW-SE extension. The local longitudinal extension observed, supported by GPS data, can be explained utilizing large scale geodynamic models.

ALBARELLO, D. (2000): A resampling approach to test stress field uniformity from fault geometries,
Geophys. J. Int., 140 (3), 535-542.
ALESSIO, G., A. GORINI, G. VILARDO and G. IANNACCONE (1996): Low energy sequences in areas with
high seismic potential: Benevento (Sourthern Apennines), April 1990, in Advances in Natural and
Technological Hazard Research-Earthquake Hazard and Risk, edited by V. SCHENK (Kluwer Academic
Publishers, Dordrecht), 3-16.
ANGELIER, J. (1990): Inversion of field data in fault tectonics to obtain the regional stress: a new rapid
direct inversion method by analytical means, Geophys. J. Int., 103 (2), 363-376.
ANGELIER, J. and P. MECHLER (1977): Sur une méthode graphique de recherche des contraintes principales
également utilisables en tectonique et en séismologie: la méthode des diedres droits (A
graphic method applied to the localization of principal stresses for fault tectonics and seismology;
the right dihedral method), Bull. Sóc. Geol. France, 19 (6), 1309-1318.
ANZIDEI, M., P. BALDI, G. CASULA, A. GALVANI, E. MANTOVANI, A. PESCI, F. RIGUZZI and E. SERPELLONI
(2001): Insights into present-day crustal motion in the Central Mediterranean area from GPS
surveys, Geophys. J. Int., 146 (1), 98-110.
BARBA, S., R. DI GIOVAMBATTISTA and G. SMRIGLIO (1995): Italian seismic databank allows on line
access, Eos, Trans. Am. Geophys. Un., 76, 9-89.
BISIO, L., R. DI GIOVAMBATTISTA, G. MILANO and C. CHIARABBA (2004): Three-dimensional earthquake
locations and upper crustal structure of the Sannio-Matese region (Southern Italy), Tectonophysics,
385 (1-4), 121-136.
BOSCHI, E., E. GUIDOBONI, G. FERRARI, G. VALENSISE and P. GASPERINI (1997): Catalogue of Strong
Italian Earthquakes, 461 B.C. to 1990 (ING-SGA, Roma-Bologna), pp. 644, with CD-ROM.
CHIARABBA, C. and A. AMATO (1997): Upper-crustal structure of the Benevento area (Southern Italy):
fault heterogeneities and potential for large earthquakes, Geophys. J. Int., 130, 229-239.
CIARANFI, N., M. GUIDA, G. IACCARINO, T. PESCATORE, P. PIERI, L. RAPISARDI, G. RICCHETTI, I.
SGROSSO, M. TORRE, L. TORIORICI, E. TURCO, R. SCARPA, M. CUSCITO, I. GUERRA, G. IANNACCONE,
G.F. PANZA and P. SCANDONE (1983): Seismotectonic elements of the Southern Apennines, Boll.
Soc. Geol. It., 102 (2-3), 201-222.
CNR-PFG (CONSIGLIO NAZIONALE DELLE RICERCHE-PROGETTO FINALIZZATO GEODINAMICA) (1983):
Neotectonic Map of Italy (Sottoprogetto Neotettonica, Dir. Barberi, Coor. Bosi), Scale 1:500000,
Sheet 4.
DI BUCCI, D., S. CORRADO and G. NASO (2002): Active faults at the boundary between Central and
Southern Apennines (Isernia, Italy), Tectonophysics, 359, 47-63.
DOGLIONI, C. (1996): Geological remarks on the relationships between extension and convergent geodynamic
settings, Tectonophysics, 252, 253-268.
EKSTRÖM, G., A. MORELLI, E. BOSCHI and A. DZIEWONSKI (1998): Moment tensor analysis of the Central
Italy earthquake sequence of September-October 1997, Geophys. Res. Lett., 25 (11), 1971-1974.
FEDERICI, P., R. DI MARO, A. MARCHETTI and M. COCCO (1992): Analisi della sismicità dell’area del
Sannio-Matese negli anni 1991-1992, in Atti dell’XI Convegno Annuale GNGTS, CNR, Roma, I,
389-404.
FOXALL, W., A. MICHELINI and T.V. MCEVILLY (1993): Earthquake travel time tomography of Southern
Santa Cruz Mountains: control of fault heterogeneity of the San Andrea Fault Zone, J. Geophys.
Res., 98, 17,691-17,710.
FREPOLI, A. and A. AMATO (2000): Spatial variation in stresses in peninsular Italy and Sicily from
background seismicity, Tectonophysics, 317, 109-124.
GASPARINI, C., G. IANNACCONE and R. SCARPA (1980): On the focal mechanisms of Italian earthquakes,
Rock Mech., 9, 85-91.
GASPARINI, C., G. IANNACCONE and R. SCARPA (1985): Fault plane solutions and seismicity of the Italian
Peninsula, Tectonophysics, 117, 59-78.
GEPHART, J.W. (1990): FMSI; a Fortran program for inverting fault/slickenside and earthquake focal
mechanism data to obtain the regional stress tensor, Comput. Geosci., 16 (7), 953-989.
GEPHART, J.W. and D.W. FORSYTH (1984): An improved method for determining the regional stress
tensor using earthquake focal mechanism data; application to the San Fernando earthquake sequence,
J. Geophys. Res., 89 (B11), 9305-9320.
HIPPOLYTE, J.C., J. ANGELIER and F. ROURE (1994): A major geodynamic change revealed by Quaternary
stress patterns in the Southern Apennines (Italy), Tectonophysics, 230, 199-210.
MILANO, G., R. DI GIOVAMBATTISTA and G. ALESSIO (1999): Earthquake swarms in the Southern
Apennines Chain (Italy): the 1997 seismic sequence in the Sannio-Matese mountains, Tectonophysics,
306, 57-58.
MILANO, G., G. VENTURA and R. DI GIOVAMBATTISTA (2002): Seismic evidence of longitudinal extension
in the Southern Appennines Chain (Italy): the 1997-1998 Sannio-Matese seismic sequence,
Geophys. Res. Lett., 29 (20), 2004, doi: 10.1029/2002GL015188.
MONTONE, P., A. AMATO and S. PONDRELLI (1999): Active stress map of Italy, J. Geophys. Res., B104
(11), 25,595-25,610.
OLDOW, J.S., B. D’ARGENIO, L. FERRANTI, G. PAPPONE, E. MARSELLA and M. SACCHI (1993): Largescale
longitudinal extension in the Southern Apennines contractional belt, Italy, Geology, 21,
1123-1126.
PATACCA, E. and P. SCANDONE (1989): Post-Tortonian mountain building in the Apennines. The role
of the passive sinking of a relic lithospheric slab, in The Lithosphere in Italy, A. BORIANI, M.
BONAFEDE, G.B. PICCARDO and G.B. VAI (Acc. Naz. Lincei), 80, 157-176.
POSTPISCHL, D. (1985): Catalogo dei terremoti Italiani dall’anno 1000 al 1980, Quad. Ric. Sci., 114
(2B), pp. 239.
SCANDONE, P., E. PATACCA, C. MELETTI, M. BELLATALLA, N. PERILLI and U. SANTINI (1990): Struttura
geologica, evoluzione cinematica e schema sismotettonico della Penisola Italiana, in Atti del Convegno
GNDT, 25-27 Giungo 1990, Pisa, 1, 119-135.
SELVAGGI, G., B. CASTELLO and R. AZZARA (1997): Spatial distribution of scalar seismic moment release
in Italy (1983-1996): seismotectonic implication for the Apennines, Ann. Geofis., XL (6),
1565-1578.
SERPELLONI, E., M. ANZIDEI, P. BALDI, G. CASULA, A. GALVANI, A. PESCI and F. RIGUZZI (2001): Geodetic
deformations in the Central-Southern Apennines (Italy) from repeated GPS surveys, Ann.
Geofis., 44 (3), 627-647.
TODA, S., R.S. STEIN and T. SAGIYA (2002): Evidence from the AD 2000 Izu Islands earthquake
swarm that stressing rate governs seismicity, Nature, 419 (6902), 58-61.
VALENSISE, G. and D. PANTOSTI (2001): The investigation of potential earthquake sources in peninsular
Italy: a review, J. Seismol., 5, 287-306.
ZHAO, D. and H. NEGISHI (1998): The 1995 Kobe earthquake; seismic image of the source zone and
its implications for the rupture nucleation, J. Geophys. Res., 103 (B5), 9967-9986.