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Looking at fault reactivation matching structural geology and seismological data
Author(s)
Language
English
Status
Published
Peer review journal
Yes
Title of the book
Issue/vol(year)
/27(2005)
Pages (printed)
(937-942)
Issued date
2005
Keywords
Abstract
Abstract
We investigate fault reactivation that occurred during the 1997 Colfiorito seismic sequence (central Italy), matching detailed structural
geology, precise earthquake locations and mechanical models of fault interaction. The Colfiorito area, within the Northern Apennines, is
characterised by a relatively recent inversion of the tectonic stress field from compression (late Miocene), to extension (late Pliocene–
Quaternary). In September–October 1997 the area experienced a protracted seismic sequence consisting of six moderate magnitude
earthquakes (5!Mw!6), that ruptured SW-dipping normal fault segments. The two main ruptures of the sequence show opposite directions
of rupture propagation and are segmented by a strike-slip fault inherited from the compressional tectonic phase. Late in the sequence this
strike-slip fault nucleated an MwZ4.3 event and an associated aftershock sequence, which we present as an example of reversal of fault slip
direction. Plotting the strike-slip events on a detailed geological map, the left-lateral strike-slip fault imaged by aftershock distribution and
focal mechanisms, strictly corresponds to the mapped N108 right-lateral strike-slip structure inherited from the compressional tectonic phase.
The two different data-sets for this strike-slip fault show the same geometry but opposite kinematics.
We analyse the coseismic elastic static stress changes due to the occurrence of the normal fault events in order to investigate the
mechanical coupling and interaction between the NW–SE oriented normal fault system and the intervening N108 inherited fault. We show
that the elastic stress perturbation increased on the shallow portion of the activated volume where the N108 structure is located, and promoted
its reactivation with a strike-slip motion. The different amount of slip experienced along the two normal faults responsible for the greater
mainshocks favoured the left-lateral strike-slip kinematics.
We investigate fault reactivation that occurred during the 1997 Colfiorito seismic sequence (central Italy), matching detailed structural
geology, precise earthquake locations and mechanical models of fault interaction. The Colfiorito area, within the Northern Apennines, is
characterised by a relatively recent inversion of the tectonic stress field from compression (late Miocene), to extension (late Pliocene–
Quaternary). In September–October 1997 the area experienced a protracted seismic sequence consisting of six moderate magnitude
earthquakes (5!Mw!6), that ruptured SW-dipping normal fault segments. The two main ruptures of the sequence show opposite directions
of rupture propagation and are segmented by a strike-slip fault inherited from the compressional tectonic phase. Late in the sequence this
strike-slip fault nucleated an MwZ4.3 event and an associated aftershock sequence, which we present as an example of reversal of fault slip
direction. Plotting the strike-slip events on a detailed geological map, the left-lateral strike-slip fault imaged by aftershock distribution and
focal mechanisms, strictly corresponds to the mapped N108 right-lateral strike-slip structure inherited from the compressional tectonic phase.
The two different data-sets for this strike-slip fault show the same geometry but opposite kinematics.
We analyse the coseismic elastic static stress changes due to the occurrence of the normal fault events in order to investigate the
mechanical coupling and interaction between the NW–SE oriented normal fault system and the intervening N108 inherited fault. We show
that the elastic stress perturbation increased on the shallow portion of the activated volume where the N108 structure is located, and promoted
its reactivation with a strike-slip motion. The different amount of slip experienced along the two normal faults responsible for the greater
mainshocks favoured the left-lateral strike-slip kinematics.
References
References
Barchi, M.R., Minelli, G., Pialli, G., 1998. The crop 03 profile: a synthesis
of results on deep structures of the Northern Apennines. Memorie
Societa` Geologica Italiana 52, 383–400.
Barchi, M.R., Galadini, F., Lavecchia, G., Messina, P., Michetti, A.M.,
Peruzza, L., Pizzi, A., Tondi, E., Vittori, E., 2000. Sintesi sulle
conoscenze delle faglie attive in Italia Centrale. Gruppo Nazionale per
la Difesa dei Terremoti, GNDT, 62pp.
Barchi, M.R., Pucci, S., Collettini, C., Mirabella, F., Massoli, D., Guazzetti,
F., Reichenbach, P., Cardinali, M., Vergoni, N., Troiani, E., Chiraz, P.,
Giombini, L., 2001. A geological map of the Colfiorito area.
Federazione Italiana Scienze della Terra (FIST) annual meeting, 2001
Chieti.
Cello, G., Mazzoli, S., Tondi, E., Turco, E., 1997. Active tectonics in the
Central Apennines and possible implications for seismic hazard
analysis in Peninsular Italy. Tectonophysics 272, 43–68.
Chiaraluce, L., Ellsworth, W.L., Chiarabba, C., Cocco, M., 2003. Imaging
the complexity of an active normal fault system: the 1997 Colfiorito
(Central Italy) case study. Journal of Geophysical Research 108 (B6),
2294.
Chiaraluce, L., Barchi, M.A., Collettini, C., Mirabella, F., Pucci, S., 2005.
Connecting seismically active normal faults with Quaternary geological
structures in a complex extensional environment: the Colfiorito 1997
case history (Northern Apennines, Italy). Tectonics 24, TC1002,
doi:10.1029/2004TC001627.
Cocco, M., Nostro, C., Ekstrom, G., 2000. Static stress changes and fault
interaction during the 1997 Umbria–Marche earthquake sequence.
Journal of Seismology 4, 501–516.
CPTI, Gruppo di Lavoro, 1999. Catalogo Parametrico dei Terremoti
Italiani, Istituto Nazionale di Geofisica, Gruppo Nazionale per la Difesa
dai Terremoti (GNDT), Storia Geofisica e Ambiente (SGA), Servizio
Sismico Nazionale (SSN), Bologna, 92pp.
Ekstro¨m, G., Morelli, A., Boschi, E., Dziewonski, A.M., 1998. Moment
tensor analysis of the central Italy earthquake sequence of September–
October 1997. Geophysical Research Letters 25, 1971–1974.
Holdsworth, R.E., Butler, C.A., Roberts, A.M., 1997. The recognition of
reactivation during continental deformation. Journal of the Geological
Society, London 154, 73–78.
King, G.C.P., Cocco, M., 2001. Fault interaction by elastic stress changes:
new clues from earthquake sequences. Advanced in Geophysics 44, 1–
38.
Lavecchia, G., Brozzetti, F., Barchi, M., Menichetti, M., Keller, J.V.A.,
1994. Seismotectonic zoning in east-central Italy deduced from analysis
of the Neogene to present deformations and related stress fields.
Geological Society of America Bulletin 106, 1107–1120.
Lavecchia, G., Minelli, G., Pialli, G., 1988. The Umbria–Marche arcuate
fold belt (Italy). Tectonophysics 146, 125–137.
Miller, S.A., Collettini, C., Chiaraluce, L., Cocco, M., Barchi, M.,
Boris, J.P.K., 2004. Aftershocks driver by a high-pressure CO2 source
at depth. Nature 427, 724–727.
Nostro, C., Cocco, M., Belardinelli, M.E., 1997. Static stress changes in
extensional regimes: an application to southern Apennines (Italy).
Bulletin Seismological Society of America 87, 234–248.
Okada, Y., 1985. Surface deformation due to shear and tensile faults in
half-space. Bulletin Seismological Society of America 75, 1135–1154.
Okada, Y., 1992. Internal deformation due to shear and tensile faults in
half-space. Bulletin Seismological Society of America 82, 1018–1040.
Pino, N.A., Mazza, S., 1999. Rupture directivity of the major shocks in the
1997 Umbria–Marche (Central Italy) sequence from regional broadband
waveforms. Geophysical Research Letters 26, 2101–2104.
Salvi, S., Stramondo, S., Cocco, M., Tesauro, M., Hunstad, I., Anzidei, M.,
Briole, P., Baldi, P., Sansosti, E., Fornaio, G., Lanari, R., Doumaz, F.,
Pesci, A., Galvani, A., 2000. Modeling coseismic displacements
resulting from SAR interferometry and GPS measurements during the
1997 Umbria–Marche seismic sequence. Journal of Seismology 4, 479–
499.
Scholz, C.H., 1998. Earthquakes and friction laws. Nature 391, 37–42.
Sibson, R.H., 1990. Rupture nucleation on unfavourably oriented faults.
Bulletin Seismological Society of America 80, 1580–1604.
Stein, R.S., 1999. The role of stress transfer in earthquake triggering.
Nature 402, 605–609.
Tavarnelli, E., 1999. Normal faults in thrust sheets: pre-orogenic extension,
post-orogenic extension, or both? Journal of Structural Geology 21,
1011–1018.
Waldhauser, F., Ellsworth, W.L., 2000. A double-difference earthquake
location algorithm: method and application to the Northern Hayward
Fault, California. Bulletin Seismological Society of America 90, 1353–
1368.
Barchi, M.R., Minelli, G., Pialli, G., 1998. The crop 03 profile: a synthesis
of results on deep structures of the Northern Apennines. Memorie
Societa` Geologica Italiana 52, 383–400.
Barchi, M.R., Galadini, F., Lavecchia, G., Messina, P., Michetti, A.M.,
Peruzza, L., Pizzi, A., Tondi, E., Vittori, E., 2000. Sintesi sulle
conoscenze delle faglie attive in Italia Centrale. Gruppo Nazionale per
la Difesa dei Terremoti, GNDT, 62pp.
Barchi, M.R., Pucci, S., Collettini, C., Mirabella, F., Massoli, D., Guazzetti,
F., Reichenbach, P., Cardinali, M., Vergoni, N., Troiani, E., Chiraz, P.,
Giombini, L., 2001. A geological map of the Colfiorito area.
Federazione Italiana Scienze della Terra (FIST) annual meeting, 2001
Chieti.
Cello, G., Mazzoli, S., Tondi, E., Turco, E., 1997. Active tectonics in the
Central Apennines and possible implications for seismic hazard
analysis in Peninsular Italy. Tectonophysics 272, 43–68.
Chiaraluce, L., Ellsworth, W.L., Chiarabba, C., Cocco, M., 2003. Imaging
the complexity of an active normal fault system: the 1997 Colfiorito
(Central Italy) case study. Journal of Geophysical Research 108 (B6),
2294.
Chiaraluce, L., Barchi, M.A., Collettini, C., Mirabella, F., Pucci, S., 2005.
Connecting seismically active normal faults with Quaternary geological
structures in a complex extensional environment: the Colfiorito 1997
case history (Northern Apennines, Italy). Tectonics 24, TC1002,
doi:10.1029/2004TC001627.
Cocco, M., Nostro, C., Ekstrom, G., 2000. Static stress changes and fault
interaction during the 1997 Umbria–Marche earthquake sequence.
Journal of Seismology 4, 501–516.
CPTI, Gruppo di Lavoro, 1999. Catalogo Parametrico dei Terremoti
Italiani, Istituto Nazionale di Geofisica, Gruppo Nazionale per la Difesa
dai Terremoti (GNDT), Storia Geofisica e Ambiente (SGA), Servizio
Sismico Nazionale (SSN), Bologna, 92pp.
Ekstro¨m, G., Morelli, A., Boschi, E., Dziewonski, A.M., 1998. Moment
tensor analysis of the central Italy earthquake sequence of September–
October 1997. Geophysical Research Letters 25, 1971–1974.
Holdsworth, R.E., Butler, C.A., Roberts, A.M., 1997. The recognition of
reactivation during continental deformation. Journal of the Geological
Society, London 154, 73–78.
King, G.C.P., Cocco, M., 2001. Fault interaction by elastic stress changes:
new clues from earthquake sequences. Advanced in Geophysics 44, 1–
38.
Lavecchia, G., Brozzetti, F., Barchi, M., Menichetti, M., Keller, J.V.A.,
1994. Seismotectonic zoning in east-central Italy deduced from analysis
of the Neogene to present deformations and related stress fields.
Geological Society of America Bulletin 106, 1107–1120.
Lavecchia, G., Minelli, G., Pialli, G., 1988. The Umbria–Marche arcuate
fold belt (Italy). Tectonophysics 146, 125–137.
Miller, S.A., Collettini, C., Chiaraluce, L., Cocco, M., Barchi, M.,
Boris, J.P.K., 2004. Aftershocks driver by a high-pressure CO2 source
at depth. Nature 427, 724–727.
Nostro, C., Cocco, M., Belardinelli, M.E., 1997. Static stress changes in
extensional regimes: an application to southern Apennines (Italy).
Bulletin Seismological Society of America 87, 234–248.
Okada, Y., 1985. Surface deformation due to shear and tensile faults in
half-space. Bulletin Seismological Society of America 75, 1135–1154.
Okada, Y., 1992. Internal deformation due to shear and tensile faults in
half-space. Bulletin Seismological Society of America 82, 1018–1040.
Pino, N.A., Mazza, S., 1999. Rupture directivity of the major shocks in the
1997 Umbria–Marche (Central Italy) sequence from regional broadband
waveforms. Geophysical Research Letters 26, 2101–2104.
Salvi, S., Stramondo, S., Cocco, M., Tesauro, M., Hunstad, I., Anzidei, M.,
Briole, P., Baldi, P., Sansosti, E., Fornaio, G., Lanari, R., Doumaz, F.,
Pesci, A., Galvani, A., 2000. Modeling coseismic displacements
resulting from SAR interferometry and GPS measurements during the
1997 Umbria–Marche seismic sequence. Journal of Seismology 4, 479–
499.
Scholz, C.H., 1998. Earthquakes and friction laws. Nature 391, 37–42.
Sibson, R.H., 1990. Rupture nucleation on unfavourably oriented faults.
Bulletin Seismological Society of America 80, 1580–1604.
Stein, R.S., 1999. The role of stress transfer in earthquake triggering.
Nature 402, 605–609.
Tavarnelli, E., 1999. Normal faults in thrust sheets: pre-orogenic extension,
post-orogenic extension, or both? Journal of Structural Geology 21,
1011–1018.
Waldhauser, F., Ellsworth, W.L., 2000. A double-difference earthquake
location algorithm: method and application to the Northern Hayward
Fault, California. Bulletin Seismological Society of America 90, 1353–
1368.
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