Journal of Geodynamics 36 (2003) 113–128
www.elsevier.com/locate/jog
Spatiotemporal evolution of the Central Apennines fault
system (Italy)
E. Tondi*, G. Cello
Dipartimento di Scienze della Terra, Università di Camerino (MC), Italy
Abstract
A variety of models show that crustal deformation is a self-organized process on long (geologic) timescales. In this paper, we analyse an active seismogenic crustal-scale fault system (the Central Apennines
Fault System or CAFS) with the aim of assessing the spatial and temporal characteristics of fault development and related earthquake activity. The basic properties of the CAFS, as derived from our study, are
then compared with those of other fault systems worldwide in order to validate/constrain the results of
available statistical physics models based on self organized criticality (SOC).
# 2003 Elsevier Ltd. All rights reserved.
1. Introduction
Available models showing that crustal deformation is a self-organized process are mostly based
on simulations of earthquake ruptures on single fault surfaces (e.g. Bak and Tang, 1989). In these
models the deforming material reaches a self-organized critical (SOC) state in which the cascade
effect due to the nearest-neighbor interactions generates a power–law distribution of earthquake
magnitudes similar to that expressed by the well known Gutenberg–Richter relation. On the other
hand, the spatial and temporal characteristics of SOC-generated fault patterns show remarkable
similarity with real data sets from differently sized fault systems characterizing different tectonic
environments and affecting a variety of rock types (Sornette and Sornette, 1989; Walsh and
Watterson, 1992; Sornette and Virieux, 1992; Cowie et al., 1993; Cowie, 1998, Cowie and
Roberts, 2001).
The aim of our work is that of defining the main attributes of a natural seismogenic fault system, exposed in the central Apennines (Fig. 1a), in order to use these data to validate/constrain
the results of the model development of faults and related earthquake activity.
* Corresponding author. Fax: +39-0737-402644.
E-mail address: [email protected] (E. Tondi).
0264-3707/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0264-3707(03)00043-7
114
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
We consider the Central Apennines Fault System (CAFS; Fig. 1) as an appropriate tectonic
feature for the analysis of the basic characteristics and the spatiotemporal properties of crustalscale active faults for the following reasons:
1. It has been investigated in great detail, in the last few years, due to its relevance for seismic
hazard assessment (SHA) in peninsular Italy (Cello and Tondi 2000; Barchi et al., 2000 and
references therein).
Fig. 1. (a) Schematic structural map of the central Apennines (the inside box includes the CAFS-related structures
shown in c). Additional information: the magnitude of the crustal earthquakes from 1970 to 1990 is shown with
squares of variable size (data from Gasparini et al., 1985 and Basili et al., 2001). (b) Simplified stratigraphic column; 1:
anhydrite (Trias); 2: shallow water limestones (Jurassic–Early Cretaceous); 3: pelagic marls and limestones (Cretaceous–Miocene). (c) The Central Apennines Fault System (CAFS); measured active surface faults and related deep
seismogenic structures are also shown (see Table 2 for data).
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
Fig. 1 (continued).
115
116
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
2. It represents the most important tectonic element in central Italy which is currently growing
(Cello, 1997) and releasing seismic energy, as shown by available data on seismic moment
release from historical earthquakes recorded in the area in the past 1000 years (Fig. 2).
3. The central Apennines Fault System includes several fault segments which are well exposed
over a large area (more than 100 km long and 40 km wide).
4. Historical catalogues and available paleosismological data furnish a good record for
medium-large earthquakes which occurred in the area in the past 1000 years (Table 1;
Boschi et al., 1997; Blumetti, 1995; Camassi and Stucchi, 1998).
2. The Central Apennines Fault System
The Late-Quaternary (post-700 ka) fault structure of the central Apennines represents a kinematically coherent network (Fig. 1c) that developed in response to the a stress field that has been
acting in the region since the Middle Pleistocene (Cello et al., 1997). It consist of a surface fault
trace pattern extending from Camerino to l’Aquila over a total length of about 100 km. Several
faults within the CAFS bound small tectonic depressions infilled with Pleistocene-Holocene
coarse-grained continental deposits and show remarkably well exposed scarps associated with the
recent activity responsible for the moderate to strong seismicity of this sector of the Apennines.
Slip data from CAFS structures (Cello et al., 1997) show that roughly N–S trending left-lateral
strike–slip and transtensional/normal (from NNW–SSE to WNW–ESE trending) faults are all
kinematically consistent with the existence of a Late-Quaternary remote stress field characterized
by a NE–SW-oriented minimum horizontal compressive stress and by a NW–SE trending maximum horizontal compressive stress. Within this framework, the extensional/transtensional features have been related to regional strike–slip deformation and to the development of a composite
Fig. 2. Block diagram showing both surface faults, belonging to a seismogenic zone, and the related seismogenic fault
(after Tondi, 2000).
117
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
Table 1
Earthquakes parameters of selected historical earthquakes recorded in central Italy over the last 1000 years between
Lat. 42 .150 and Lat. 43 .300 and between Long. 12 and Long. 14 (Database from Boschi et al., 1997; Camassi and
Stucchi, 1998 and Ekstrom et al., 1998)
Year
Latitude
Longitude
Epicentral Zone
Imax
Me (Mw)
Database
1279
1298
1328
1349
1349
1461
1480
1599
1639
1639
1695
1703
1703
1703
1730
1747
1751
1762
1785
1786
1799
1832
1859
1865
1873
1917
1943
1961
1979
1984
1997
1997
43.27
42.55
42.85
42.62
42.17
42.32
42.90
42.72
42.63
42.65
42.62
42.68
42.62
42.47
42.45
43.22
43.23
42.30
42.53
42.32
43.15
42.97
42.79
43.28
43.08
42.58
42.92
42.40
42.72
43.25
43.00
43.00
12.78
12.83
13.02
12.12
13.38
13.55
13.80
13.00
13.27
13.25
12.10
13.12
13.10
13.20
13.08
12.78
12.73
13.58
12.78
13.37
13.13
12.60
13.01
12.32
13.25
12.63
13.65
13.05
13.07
12.52
12.60
12.60
Colfiorito
Rieti
Norcia
Viterbese-Umbria
Aquilano
Aquilano
Marche meridionali
Cascia
Amatrice
Amatrice
Lazio settentrionale
Norcia
Montereale
L’Aquila
Leonessa
Appennino umbro-marchigiano
Appennino umbro
Aquilano
Umbria meridionale
L’Aquila
Appennino marchigiano
Valle del Topino
Norcia
Umbria settentrionale
Marche meridionali
Ternano
Marche meridionali-Abruzzo
Valle del Velino
Norcia
Umbria settentrionale
Colfiorito
Colfiorito
9
9.5
10
8.5
10
10
7.5
8.5
10
10
9
11
8
10
9
8.5
10
9.5
8.5
8
9.5
10
8.5
7.5
9
7.5
9
8
8.5
8
7
8
6.4
6.2
6.2
6.3
7
6.2
5.2
5.9
5.5
6
6
6.7
6
6.6
6.3
5.7
6.2
5.6
5.6
5.6
5.9
6.1
5.9
5.2
6
5.1
5.9
5.1
(5.8)
5.6
(5.7)
(6)
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Camassi and Stucchi, 1998
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Camassi and Stucchi, 1998
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Boschi et al., 1997
Ekstrom et al., 1998
Ekstrom et al., 1998
negative flower structure which represents the surface expression of a crustal scale left-lateral
brittle shear zone (Cello et al., 1997).
As shown in Fig. 1c, the active faults of the CAFS consist of arrays of distinct overlapping
segments which in 3D may either be unconnected or linked vertically or laterally into a single
continuous fault surface. Moreover, unconnected neighboring faults may interact with one
another through their stress fields, hence promoting distinctive earthquake sequences (Gupta and
Scholz, 2000, and references therein). In this tectonic context, segmentation for SHA may only
rarely be applied to individual surface faults; rather, as suggested by Cello et al. (1997) it shouldapply to volumes or, to a first approximation, areas. For simplicity, following Tondi (2000), we
assume that the surface faults belonging to each seismogenic zone (i.e. the Norcia Seismic Zone
118
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
or the Colfiorito Seismic Zone; Fig. 1c) responsible for generating single seismic events with
multiple ruptures (as in the case of the Norcia, 1979 and Colfiorito, 1997 earthquakes) are the
surface manifestations of earthquake-related deformation (Fig. 2 and Table 2).
2.1. Historical earthquakes in central Italy
Seismicity, in the axial zones of the central Apennines, is (mainly) associated with CAFS
structures and is mostly characterized by moderate earthquakes (Fig. 1). However, a few major
Table 2
Length displacement values, and kinematics of the active surface faults (a) and related deep seisomgenic structures (b)
belonging to the CAFS (see Fig. 1 for location)
Np.
Surface active fault
Length, km
Kinematic
Displacement, m
a1
a2
a3
A4
B1
B2
B3
B4
B5
C1
D1
D2
D3
E1
F1
G1
H1
Colfiorito
Colfiorito
Colfiorito
Colfiorito
Norcia
Norcia
Norcia
Norcia
Norcia
Mt. Vettore
Cascia
Cascia
Cascia
Chiavano
Leonessa
F. Velino
Pizzoli
9
5.5
7
7.5
27.8
15.5
4
2.6
2.6
6
3.6
3.4
3.3
13
11.7
16
13.3
Oblique
Oblique
Oblique
Strike–slip
Oblique
Dip–slip
Dip–slip
Oblique
Oblique
Oblique
Dip–slip
Dip–slip
Dip–slip
Strike–slip
Dip–slip
Strike–slip
Dip–slip
240
110
170
650
900
400
40
90
100
150
150
200
100
900
450
1200
500
Seismogenic Fault
Length, km
Colfiorito
Preci-Cittareale
Preci
Norcia
Castel S. Maria
Mt. Vettore
Cascia
Leonessa
Amatrice
Montereale
Pizzoli-L’Aquila
Pizzoli
L’Aquila
Lucoli
12.3
27.5
9.8
8.7
9
18
7.2
11.7
8.4
10.5
34
19.5
14.5
8.3
(b)
1
2
2a
2b
2c
3
4
5
6
7
8
8a
8b
9
119
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
historical events within the Umbria–Marche–Abruzzi sector show maximum intensities of X–XI
degrees MCS and equivalent magnitudes around 6.5–7.0. The earlier data have been derived from
the most recent Parametric Catalogue of Earthquakes (Boschi et al., 1997; Camassi and Stucchi,
1998), which furnishes accurate locations, and the values of the equivalent magnitude of the
major earthquakes which occurred in central Italy over the past 1000 years. In Table 1 we also
report the historical earthquakes that occurred in central Italy along a transect between Lat.
42 .150 and Lat. 43 .300 , and between Long. 12 and Long. 14 . Based on the well-known relation
between magnitude and seismic moment (Kanamori, 1977):
m ¼ ðlog10 Mo=1:5Þ 10:73
ð1Þ
we use the equivalent magnitude of each historical event to calculate its seismic moment release
(see also Westaway, 1992) by employing the expression:
Mo ¼ 10ðmþ10:73Þ1:5 :
ð2Þ
By doing so, we estimate (Fig. 3a) the seismic moments released by the historical earthquakes
reported in Table 1. As can be seen, most of the energy released from earthquakes in central Italy
(more than 90%) is related to the current deformation history and growth of CAFS structures
(see also Cello and Tondi, 2000). Furthermore, if one looks at the magnitude (Fig. 3b) and the
seismic moment release (Fig. 3c) within the CAFS as a function of time, it can be noted that, in
the last millennium, the seismic energy released was similar in two distinct episodes with Me>6.5
which occurred at a time interval of ca. 350 years. Combining this type of information with
available structural and paleoseismological data (Brozzetti and Lavecchia, 1994; Calamita et al.,
1994b; Blumetti, 1995; Cello et al., 1997, 1998; Tondi et al., 1997; Barchi et al., 2000; Tondi, 2000)
it is possible to relate each historical earthquake to its correlative seismogenic fault (refer to
Fig. 1c, and Table 3).
Table 3
Historical earthquakes and correlative seismogenic faults. Inferred seismic moments, fault areas, and coseismic displacements are also shown
Year Latitude Longitude Epicentral
zone
Imax Me
Seismogenic
(MW) Fault
Fault Mo
length,
km
Fault
area,
cm2
Coseismic
displacement,
cm
1279
1328
1349
1599
1639
1703
1703
1703
1730
1786
1859
1979
1997
9
6.4
10
6.2
10
7
8,5
5.9
10
6
11
6.7
8
6
10
6.6
9
6.3
8
5.6
8.5
5.9
8.5 (5.8)
8
(6)
12.3
9.8
34
7.2
8.4
27.5
10.5
19.5
11.7
6.3
8.7
9
12.3
1.5E+12
9.6E+11
4.1E+12
5.2E+11
112
86
321
56
43.27
42.85
42.17
42.72
42.65
42.68
42.62
42.47
42.45
42.32
42.79
42.72
43.00
12.78
13.02
13.38
13.00
13.25
13.12
13.10
13.20
13.08
13.37
13.01
13.07
12.60
Colfiorito
Norcia
L’Aquila
Cascia
Amatrice
Norcia
Montereale
L’Aquila
Leonessa
L’Aquila
Norcia
Norcia
Colfiorito
Colfiorito
Preci
Pizzoli-L’Aquila
Cascia
Amatrice
Preci-Cittareale
Montereale
Pizzoli
Leonessa
Lucoli
Norcia
Castel S. Maria
Colfiorito
4.9E+25
2.5E+25
3.9E+26
8.8E+24
1.2E+25
1.4E+26
1.2E+25
9.9E+25
3.5E+25
3.1E+24
8.8E+24
6.2E+24
1.2E+25
7.1 E+12 69
3.3E+12 141
1.1E+12
38
2.3E+12 141
1.4E+12
85
4E+11
26
6.4E+11
45
7.7E+12
27
120
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
Fig. 3. (a) Cumulative seismic moments from historical earthquakes occurred between Lat. 42.15 and Lat. 43.30 and
between Long. 12 and Long. 14 showing that most (about 90%) of the seismic energy was released by CAFS-related
earthquakes. (b) Graphical representation of the equivalent magnitude of CAFS-related historical earthquakes vs.
time. (c) Cumulative seismic moment release associated to the historical earthquakes reported in (b). Dark bar shows
the seismic energy released by earthquake with magnitude > 6.5.
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
121
Fig. 4. Fault length (data from Table 2b) vs. moment (data from Table 3) of the historical earthquakes shown in
Fig. 2b.
Once the seismogenic fault corresponding to each historical earthquake is known, together with
its equivalent magnitude, the computed seismic moment can be compared with the length of the
seismogenic fault. The results, illustrated in Fig. 4, are similar to those derived from other areas
worldwide (Kanamori and Anderson, 1975; Scholz et al., 1986); in particular the scaling relation
derived for the CAFS is comparable with that obtained for ‘‘small’’ earthquakes (sensu Scholz,
2002) where MoL3. This result suggests therefore that most of the analyzed earthquakes are
characterized by source dimensions that are smaller than the width of the seismogenic layer (ca.
12 km; Deschamps et al., 1984).
3. Characteristic rupture patterns for CAFS structures
The well-established relation:
Mo ¼ Au
ð3Þ
where: A=fault surface area; =rigidity modulus=3.1011 dyne/cm2; du=last slip increment on
the fault, allows the coseismic slip during a single seismic event to be evaluated once the maximum length of the seismogenic fault responsible for a related historical earthquake is known.
The estimates derived from the earlier expression for CAFS structures are reported in Table 3;
they are in good agreement with estimates obtained from available paleoseismological data
(Blumetti, 1995; Cello et al., 1998), and conform to the scaling relations between fault length and
slip published by Wells and Coppersmith (1994). Moreover, in Fig. 5 we show the cumulative
displacement accumulated on all CAFS structures over the last millennium (Fig. 5a; continuous
lines), and that computed at four specific sites along the system (lines 1, 2, 3, 4 in Fig. 5b). As can
be seen, the largest events are associated with synchronous steps in the profiles 2 and 3, with
larger displacements in the central sectors of the CAFS. We also note that the steps are quite
regular, hence, if one assumes that a time window of about one millennium is long enough to
characterize the slip pattern of the fault system as a whole, then CAFS structures may be
122
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
Fig. 5. Spatiotemporal evolution of earthquakes within the CAFS. (a) Cumulative displacement as a function of time,
shown as a total and at four different points along the system. Note that the continuous line steps (total displacement
on the CAFS) are regular, so, the system appears to be (i) ‘‘slip-predictable’’ and (ii) ‘‘time-predictable’’ (Shimazaki
and Nakata, 1980). (b) latitude coordinates of ruptured seismogenic faults.
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
123
considered to be both ‘‘time and slip-predictable’’ (Shimazaki and Nakata, 1980). Accordingly,
we can speculate that the average recurrence time for large earthquakes in central Italy is about
350 years, and that the displacement rate of the whole system is 1.6 cm/year.
3.1. Scaling properties of CAFS-related earthquakes
The Gutenberg–Richter equation:
LogN ¼ A bm
ð4Þ
is often used in SHA to evaluate the maximum credible earthquake in a given time window.
The b value usually observed for natural earthquake populations is 0.7–1.5 (Scholz, 1982;
Pacheco et al., 1992).
In Fig. 6 we show the Log N– m relation derived for CAFS-related earthquakes (data from
Table 1); as can be seen, the computed b value is 0.8. This corroborates the validity of the
moment–length relation of Fig. 4, as value of b of 0.8 also indicates that most of the historical
earthquakes in central Italy can be classified as small earthquakes (see Scholz, 1982). Moreover,
the magnitude of the maximum expected event almost coincides with the largest historical events
(1349 and 1703) occurred in central Italy in the last millennium (Fig. 6).
A different scaling property of CAFS-related earthquakes can be assessed by relating coseismic
slip and length of the ruptured fault (see, for example, Romanowicz and Rundle, 1993). The point
distribution in Fig. 7 emphasizes that CAFS-related structures display coseismic slip (data from
Table 3) and fault displacement (data from Table 2a) that are proportional to the length of the
seismogenic fault (data from Table 2b) with D/ L1.2 and to the length of the surface fault (data
from Table 2a) with D/ L1.15. Similar results have been obtained by Watterson (1986), Walsh
and Watterson (1988), Marret and Allmendinger (1991), Gillespie et al. (1992), Cowie and Scholz
(1992a, b) and Schlische et al., (1996). The scaling relationships shown in Fig. 8 emphasize that
Fig. 6. Cumulative distribution of the equivalent magnitudes of the earthquakes occurring within the CAFS (data
from Table 3).
124
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
Fig. 7. Log–Log plots of (a) coseismic slip (data from Table 3) vs. seismogenic fault length (data from Table 2b); (b)
fault displacement vs. surface fault length (data from Table 2a), inferred for CAFS structures.
the fault dimensional parameters of CAFS-related structures can be expressed by a power–law
relation of the form (Mandelbrot, 1983):
Nð 5 SÞ ¼ aSD
ð5Þ
where N(5S) is the number of features having a size greater than or equal to S (e.g. the fault
length or displacement); a is a measure of the sample size, and the power–law exponent D (i.e. the
absolute slope of the line) is the fractal dimension of the analyzed population. The graph of
Fig. 8a displays an exponent D=1.5. Exponent D may also be derived from statistical physics
models of fault growth. Sornette et al. (1990) and Cowie et al. (1993) show that, as the material is
increasingly deformed, D decreases from a value of about 2.0 to D=1.0 when a major fault
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
125
Fig. 8. Cumulative distribution of the (a) seismogenic fault length (data from Table 2b); (b) coseismic slip (data from
Table 3); (c) surface fault length (data from Table 2a) and (d) fault displacement (data from Table 2a) inferred for
CAFS structures.
extends all across the model. Accordingly, we suggest that D=1.5 may be indicative of a low
degree of maturity of the system. The same result was also obtained by Cello (1997) who analyzed
CAFS structures using a box-counting technique.
The diagrams of Fig. 8c and 8d both display a clear break in the population distribution. This
occurs at a length of about 10 km, in Fig. 8c, and for displacement values between 200–300
meters, in Fig. 8d. As concerns the length distribution (Fig. 8c), it can be seen that for L< 10 km
the relation is characterized by a D value=0.7, whereas for L>10 km d=2. Because the thickness
of the seismogenic layer, in this sector of the Apennines is 10–12 km, we tentatively suggest that
the two relations can be used, the first, to describe the distribution of small faults (which do not
break the whole seismogenic crust) and, the second, that of large faults that do.
4. Summary and conclusions
An active crustal-scale fault system, the Central Apennines Faults System (CAFS), was analyzed in detail in order to assess the spatial and temporal characteristics of fault development and
related earthquake activity. The main results of our work may be summarized as follows:
1. The CAFS is a multi-scalar seismogenic fault structure including strike-slip and normal/
transtensional active fault segments. The cumulative distribution of fault lengths within the
126
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
2.
3.
4.
5.
6.
CAFS is expressed by the relation N(5S)=aSD. The value D=1.5 of the exponent of the
power law suggests that the system is an immature still-growing fault structure.
The displacement rate of the whole system in the last 700 ka is 1.6 cm/year.
The two largest earthquakes recorded within the CAFS (1349–1703 A.D.) account for
approximately 90% of the total seismic energy released by the system in the last millennium.
Given the assumption that one millennium is a time period long enough to characterize the
slip pattern of the CAFS, the cumulated coseismic slip patterns can be interpreted in terms
of ‘‘time-predictable’’ and ‘‘slip-predictable’’ models, and the average recurrence time for
M>6.5 events is about 350 years.
The b value of the Gutemberg–Richter relation for CAFS-related earthquakes is 0.8; the
magnitude of the maximum expected event coincides with the largest historical event.
The exponent of the relation between seismogenic fault length and seismic moment is 2.6;
this suggests that most of the seismic events in central Italy can be considered as small
earthquakes (with MoL3).
In conclusion, we believe that a structural approach to the study of crustal-scale fault systems
may be useful to validate/constrain possible models of brittle crustal deformation by supplying
real data on the spatiotemporal evolution of natural systems which are nicely exposed; this is
because one can directly observe in the field the various modes of interaction and linkage among
differently-sized structures showing a variable degree of maturity.
Acknowledgements
This work has been supported by MIUR Cofin 2002 (Resp. G. Cello, prot. 2002043912). We
wish to thank P. Gillespie and G. Roberts who helped us to improve the overall quality of this
paper.
References
Bak, P., Tang, C., 1989. Earthquakes as a self-organized critical phenomenon. Journal of Geophysical Research 94,
15635–15637.
Barchi, M., Galadini, F., La vecchia, G., Messina, P., Michetti, A.M., Peruzza, L., Pizzi, A., Tondi, E., Vittori, E.,
2000. Sintesi delle conoscenze sulle faglie attive in Italia Centrale: parametrizzazione ai fini della caratterizzazione
della pericolosità sismica. NR-Gruppo Nazionale per la Difesa dai Terremoti, Roma.
Basili, R., Bordoni, P., Burrato, P., Nappi, R., Pantosti, D., Spinelli, A., Valensise, G., 1992. Database of potential
sources for earthquakes lager than M 5.5 in Italy. Annali di Geofisica 44 (4), 964.
Blumetti, A.M., 1995. Neotectonic investigation and evidence of paleosesmicity in the epicentral area of the January–
February 1703, central Italy, earthquake. In: Serva, L., Slemmons, D. B. (Eds.), Perspectives in Paleoseismology, 6,
pp. 83–100.
Boschi, E., Guidoboni, E., Ferrari, G., Valensise, G., Gasperini, P. (Eds.), 1997. Catalogo dei forti terremoti in Italia
dal 461 a.C. al 1990, 2644. ING-SGA, Bologna.
Brozzetti, F., Lavecchia, G., 1994. Seismicity and related extensional stress field: the case of the Norcia Seismic Zone
(Central Italy). Ann. Tectonicae 8, 36–57.
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
127
Calamita, F., Coltorti, M., Farabollini, P., Pizzi, A., 1994. Le faglie normali quaternarie nella Dorsale appenninica
umbro-marchigiana. Proposta di un modello di tettonica d’inversione. Studi Geol. Camerti Vol. spec, 211–225.
Camassi, R., Stucchi, M., 1998. NT4.1, a Parametric Catalogne of Damaging Earthquakes in the Italian Area (release
NT4.1.1). GNDT, Milano.
Cello, G., 1997. Fractal analysis of a Quaternary fault array in the Central Apennines, Italy. Journal of Structural
Geology 19 (7), 945–953.
Cello, G., Tondi, E., 2000. The Resolution of Geological Analysis and Models for Earthquake Faulting Studies.
Journal of Geodynamics 29, 149.
Cello, G., Mazzoli, S., Tondi, E., 1998. The 1703 seismic sequence of central Italy: a major evidence of a crustal seismogenic zone in the Umbria-Marche-Abruzzi Apennines. Journal of Geodynamics 26, 443–460.
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.
Cowie, P.A., 1998. A healing-reloading feedback control on the growth rate of seismogenic faults. Journal of Structural
Geology 20, 1075–1087.
Cowie, P.A., Scholz, C.H., 1992a. Physical explanation for the displacement–length scaling relationship for faults using
a post-yield fracture mechanics model. Journal of Structural Geology 14, 1133–1148.
Cowie, P.A., Scholz, C.H., 1992b. Displacement–length scaling relationship for faults: data synthesis and discussion.
Journal of Structural Geology 14, 1149–1156.
Cowie, P.A., Roberts, G., 2001. Constraining slip rates and spacings for active normal faults. Journal of Structural
Geology 23, 1901–1925.
Cowie, P.A., Vanneste, C., Sornette, D., 1993. Statistical physics model for the spatiotemporal evolution of faults.
Journal of Geophysical Research 98, 21809–21821.
Deschamps, A., Iannaccone, G., Scarpa, R., 1984. The Umbrian earthquake (Italy) of 19 September 1979. Ann. Geophys. 2, 29–36.
Ekstrom, 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.
Gasparini, C., Iannaccone, G., Scarpa, R., 1985. Fault-plane solutions and seismicity of the Italian peninsula. Tectonophysics 117, 59–78.
Gillespie, P.A., Walsh, J.J., Watterson, J., 1992. Limitations of dimension and displacement data from single faults and
the consequences for data analysis and interpretation. Journal of Structural Geology 14, 1157–1172.
Gupta, A., Scholz, C.H., 2000. A model of normal fault interaction based on observations and theory. Journal of
Structural Geology 22, 865–879.
Mandelbrot, B.B., 1983. The Fractal Geometry of Nature. W. H. Freeman, San Francisco.
Marret, R., Allmendinger, R.W., 1991. Estimates of strain due to brittle faulting-sampling of fault populations. Journal of Structural Geology 13, 735–738.
Kanamori, H., 1977. The energy release in great earthquakes. Journal of Geophysical Research 82, 2981–2987.
Kanamori, H., Anderson, D., 1975. Theoretical basis of some empirical relations in seismology. Bulletin of Seismological Society of America 65, 1073–1095.
Pacheco, J., Scholz, C.H., Sykes, L.R., 1992. Changes in frequency-size relationship from small to large earthquakes.
Nature 335, 71–73.
Romanowicz, B., Rundle, J.B., 1993. On scaling relations for large earthquakes. Bulletin of Seismological Society of
America 83, 1294–1297.
Schlische, R.W., Young, S.S., Ackermann, R.V., Gupta, A., 1996. Geometry and scaling relations of a population of
very small rift-related normal faults. Geology 24, 683–686.
Scholz, C.H., 1982. Scaling law for large earthquakes: consequences for physical models. Bulletin of Seismological
Society of America 72, 1–14.
Scholz, C.H., 2002. The Mechanics of Earthquakes and Faulting, second ed.. Cambridge University Press, Cambridge.
Scholz, C.H., Aviles, C., Wesnousky, S., 1986. Scaling differences between large intraplate and interplate earthquakes.
Bulletin of Seismological Society of America 76, 65–70.
Shimazaki, K., Nakata, T., 1980. Time-predictable recurrence model for large earthquakes. Geophysical Research
Letters 7, 279–282.
128
E. Tondi, G. Cello / Journal of Geodynamics 36 (2003) 113–128
Sornette, A., Sornette, D., 1989. Self-organized critically and earthquakes. Europhys. Lett. 9, 197–202.
Sornette, A., Davy, P., Sornette, D., 1990. Growth of fractal fault patterns. Phys. Rev. Lett. 65, 2266–2269.
Sornette, D., Virieux, J., 1992. Linking short-timescale deformation to long-timescale tectonics. Nature 357, 401–403.
Tondi, E., 2000. Geological analysis and seismic hazard in the Central Apennines. In: Cello, G., Tondi, E. (Eds.), The
resolution of geological analysis and models for earthquake faulting studies. Journal of Geodynamics 29 (3–5), 517–
534.
Tondi, E., Cello, G., Mazzoli, S., 1997. Strutture sismogenetiche in Appennino centrale: potenziale sismico, analisi
frattale e processi di crescita. Il Quaternari 10 (2), 409–414.
Watterson, J., 1986. Fault dimension, displacement and growth. Pageoph 124, 365–373.
Walsh, J.J., Watterson, J., 1988. Analysis of the relationship between displacements and dimensions of faults. Journal
of Structural Geology 10, 239–247.
Walsh, J.J., Watterson, J., 1992. Populations of faults and fault displacements and their effects on estimates of faultrelated regional extension. Journal of Structural Geology 14, 701–712.
Wells, D.L., Coppersmith, K.J., 1994. New empirical relationships among magnitude, rupture length, rupture width,
rupture area, and surface displacement. Bulletin of Seismological Society of America 84, 974–1002.
Westaway, R., 1992. Seismic moment summation for historical earthquakes in Italy: tectonic implications. Journal of
Geophysical Research 97 (15), 15–437-464.