We discuss the mechanics of crustal normal fault-related earthquakes, and show that they represent dissipation of gravitational potential energy (graviquakes) and their magnitude increases with the involved volume (delimited by the seismogenic fault and an antithetic dilated wedge in its hangingwall), and the fault dip. The magnitude increases with the deepening of the brittle–ductile transition (BDT), which in turn enlarges the involved volume. The fault dip seems rather controlled by the static friction of the involved crustal layers. We apply the model to the extensional area of the Italian peninsula, whose geodynamics is controlled by the Alpine and Apennines subduction zones. The latter has a well-developed backarc basin and a large part of the accretion- ary prism is affected by on-going extensional tectonics, which is responsible for most of peninsular Italy seismic- ity. Analyzing the seismic record of the Apennines, the length of seismogenic normal faults tends to be at most about 3 times the hypocenter depth. We compile a map of the brittle–ductile transition depth and, assuming a fixed 45° or 60° fault dip and a dilated wedge developed during the interseismic period almost perpendicular to the fault plane, we compute the maximum volume of the hangingwall collapsing at the coseismic stage, and estimate the maximum expected magnitude. Lower magnitude values are obtained in areas with thinner brittle layer and higher heat flow. Moreover, lower magnitude relative to those theoretically expected may occur in areas of higher strain rate where faults may creep faster due to lower frictional values.

Graviquakes in Italy / Petricca, Patrizio; Barba, S.; Carminati, Eugenio Ambrogio Maria; Doglioni, Carlo; Riguzzi, F.. - In: TECTONOPHYSICS. - ISSN 0040-1951. - STAMPA. - 656:(2015), pp. 202-214. [10.1016/j.tecto.2015.07.001]

Graviquakes in Italy

PETRICCA, PATRIZIO;CARMINATI, Eugenio Ambrogio Maria;DOGLIONI, Carlo;
2015

Abstract

We discuss the mechanics of crustal normal fault-related earthquakes, and show that they represent dissipation of gravitational potential energy (graviquakes) and their magnitude increases with the involved volume (delimited by the seismogenic fault and an antithetic dilated wedge in its hangingwall), and the fault dip. The magnitude increases with the deepening of the brittle–ductile transition (BDT), which in turn enlarges the involved volume. The fault dip seems rather controlled by the static friction of the involved crustal layers. We apply the model to the extensional area of the Italian peninsula, whose geodynamics is controlled by the Alpine and Apennines subduction zones. The latter has a well-developed backarc basin and a large part of the accretion- ary prism is affected by on-going extensional tectonics, which is responsible for most of peninsular Italy seismic- ity. Analyzing the seismic record of the Apennines, the length of seismogenic normal faults tends to be at most about 3 times the hypocenter depth. We compile a map of the brittle–ductile transition depth and, assuming a fixed 45° or 60° fault dip and a dilated wedge developed during the interseismic period almost perpendicular to the fault plane, we compute the maximum volume of the hangingwall collapsing at the coseismic stage, and estimate the maximum expected magnitude. Lower magnitude values are obtained in areas with thinner brittle layer and higher heat flow. Moreover, lower magnitude relative to those theoretically expected may occur in areas of higher strain rate where faults may creep faster due to lower frictional values.
2015
Graviquakes; Italian seismicity; Normal fault earthquakes; Seismic volume; Earth-Surface Processes; Geophysics
01 Pubblicazione su rivista::01a Articolo in rivista
Graviquakes in Italy / Petricca, Patrizio; Barba, S.; Carminati, Eugenio Ambrogio Maria; Doglioni, Carlo; Riguzzi, F.. - In: TECTONOPHYSICS. - ISSN 0040-1951. - STAMPA. - 656:(2015), pp. 202-214. [10.1016/j.tecto.2015.07.001]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/789996
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