AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY 
STRONG EARTHQUAKES IN THE SOUTHERN APENNINES (ITALY) 


S. PORFIDO1, E. ESPOSITO1,E. VITTORI2, G. TRANFAGLIA3, A.M. MICHETTI4, 
M. BLUMETTI5, L. FERRELI2, L. GUERRIERI2 and L. SERVA2 
1Istituto di Ricerca Geomare Sud -C.N.R., Via A. Vespucci, 9, 80142, Napoli, Italy 
E-mail: porfido@gms01.geomare.na.cnr.it 
2ANPA – Agenzia Nazionale per la Protezione dell’Ambiente, Via Vitaliano Brancati, 48, 00144, 
Rome, Italy 
3Servizio Idrografico e Mareografico, Via Marchese Campodisola 21, 80133 Napoli, Italy 
4Dipartimento di Scienze CC.FF.MM, Universitá dell’Insubria, Via Lucini, 3, 22100, Como, Italy 
5Dipartimento Servizi Tecnici Nazionali -Servizio Sismico, Via Curtatone, 3, 00185, Rome, Italy 
(Received 2 January 2002; Accepted 17 June 2002) 

Abstract. Moderate to strong crustal earthquakes are generally accompanied by a distinctive pattern 
of coseismic geological phenomena, ranging from surface faulting to ground cracks, landslides, 
liquefaction/compaction, which leave a permanent mark in the landscape. Therefore, the repetition 
of surface faulting earthquakes over a geologic time interval determines a characteristic morphology 
closely related to seismic potential. To support this statement, the areal distribution and dimensions 
of effects of recent historical earthquakes in the Southern Apennines are being investigated in detail. 
This paper presents results concerning the 26 July 1805 earthquake in the Molise region, (I 
=X 
MCS, M 
= 6.8), and the 23 November 1980 earthquake in the Campania and Basilicata regions (I 
=XMSK, Ms 
= 6.9). Landslide data are also compared with two other historical earthquakes in the 
same region with similar macroseismic intensity. The number of significant effects (either ground 
deformation or hydrological anomalies) versus their minimum distance from the causative fault have 
been statistically analyzed, finding characteristic relationships. In particular, the decay of the number 
of landslides with distance from fault follows an exponential law, whereas it shows almost a rectilinear 
trend for liquefaction and hydrological anomalies. Most effects fall within the macroseismic area, 
landslides within intensity V to VI, liquefaction effects within VI and hydrological anomalies within 
IV MCS/MSK, hence at much larger distances. A possible correlation between maximum distance 
of effects and length of the reactivated fault zone is also noted. Maximum distances fit the envelope 
curves for Intensity and Magnitude based on worldwide data. These results suggest that a careful 
examination of coseismic geological effects can be important for a proper estimation of earthquake 
parameters and vulnerability of the natural environment for seismic hazard evaluation purposes. 

Key words: active tectonics, ground effects, historical seismicity, Italy, seismic hazard, seismic 
landscape, seismite, Southern Apennines 

1. Introduction 
Tectonic crustal structures capable of producing moderate to strong (surface wave 
magnitude Ms 
> 
5.5) earthquakes typically generate permanent environmental 
changes, by the occurrence of peculiar geomorphic features: surface faulting, uplift 


Surveys in Geophysics 23: 529–562, 2002. 
© 2002 Kluwer Academic Publishers. Printed in the Netherlands. 



S. PORFIDO ET AL. 
and subsidence, slope failures, drainage changes – including temporary or permanent 
damming, liquefaction, compaction and hydrogeological anomalies. Just after 
a large crustal earthquake, these elements characterize the scenery as scattered “irregularities”; 
with time they become integrated components of the landscape. The 
repeated occurrence of these features (which can be considered as seismites, sensu 
Vittori et al., 1991), leaves a signature in the recent stratigraphy and topography 
of an area (paleoseismic evidence), which is related to the potential magnitude and 
repeat interval of the local seismicity and to the local geological framework. This is 
the recently introduced concept of “seismic landscape” (Serva, 1995; Michetti and 
Hancock, 1997), which postulates that, once the geodynamic and climatic environments 
of an area have been properly taken into account, the geomorphological 
setting is a reliable indicator of its level of seismicity, and must be included in the 
assessment of seismic hazard. 

Therefore, a detailed characterization of permanent and temporary ground 
effects, for documented earthquakes from selected sample areas with specific tectonic 
environments, is a basic tool to define the seismic landscape to be expected 
for a given region and level of seismicity. This also represents also a valid backanalysis 
tool for assessing the actual vulnerability of the environment, and for 
predicting its future response to significant releases of seismic energy (Serva, 1994; 
Esposito et al., 1997a; Jibson et al., 1998; Parise and Jibson, 2000; Keefer, 2000, 
Wasowski and Del Gaudio, 2000), which is much needed for a proper definition of 
land use codes and land planning in seismic areas. 

Depending on the geological environment and the magnitude of the event, the 
scenery following an earthquake is distinctive. Significant recent examples come 
from the 17 January 1995, Kobe earthquake in Japan (body wave magnitude Mw 
= 
7.1, intensity X–XI MM – Mercalli Modified scale: EQE Summary report, 1995; 
Bardet et al, 1995; Sassa et al., 1996) and the 17 August 1999, Kocaeli earthquake 
in Turkey (Mw 
= 7.4, intensity X MM: USGS, 1999; EERI, 1999); these events 
were followed by a wide suite of primary (surface faulting) and secondary (mainly 
liquefaction, soil settlement and landslides) effects clearly related to the distance 
from the ruptured faults. Particularly impressive was the coastal submergence in 
the Goluck area, a common phenomenon along the coastal regions of eastern and 
central Mediterranean Sea (JSCE, 1999). 

The detailed description of ground ruptures is a relatively common feature in 
the historical reports of many destructive seismic events in Southern Italy (Figure 
1), such as the 1980 and 1930 Irpinia, the 1857 Basilicata, the 1805 Molise, the 
1783 Calabria, the 1694 Irpinia, the 1688 Benevento and the 1456 southern Italy 
earthquakes (Serva, 1985; Figliuolo, 1988; Porfido, et al. 1991; Michetti et al., 
1997; Esposito et al., 2000). As an example, the February 1783 Calabria earthquake 
(macroseismic magnitude M 
=6.9, I 
= XI MCS – Mercalli Cancani Sieberg 
macroseismic scale) produced what has been called a “geomorphogenetic crisis” 
(Cotecchia et al., 1986a), changing for ever the geography of large part of the 
region. Many landslides dammed valley floors producing at least 215 permanent 


AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 531 


Figure 1. Historical earthquakes of Intensity = 
IX MCS (from CPTI, 1999) and capable faults (from 
ITHACA database, Michetti et al., 2000c) in the Southern Apennines, superimposed on a digital 
elevation model of the region showing an immature basin and range-like morphology. 

or ephemeral lakes; many ground cracks and extensive liquefaction took place, 
followed by flood waves and eruptions of ground water with characteristic sand 
volcanoes. As well, the other large historical earthquakes have left a clear mark 
in the landscape, mainly, but not only, of their epicentral region. For all these 
earthquakes, a detailed macroseismic field is available, essentially based on the 
amount of damages to buildings, according to the MCS or MSK scales (Postpischl, 
1985). 

In order to search for regularities which may help in the interpretation of the 
correct size of the events and in the assessment of seismic hazard (e.g., the distribution 
of ground effects with respect to the causative fault), this paper analyzes 
the characteristics and the spatial distribution of ground effects of events with 
comparable magnitudes that occurred in the Southern Apennines in the last two 
centuries. A detailed description is given for the Molise event of 1805 (macroseismic 
Magnitude M 
= 6.8), and the Irpinia–Lucania event of 1980 (Ms 
= 6.9), for 
which a wide collection of information is available. Some of these data are also 
compared with those existing for other well studied earthquakes in Southern Italy. 


S. PORFIDO ET AL. 
2. Methods 
Knowledge the 1980 earthquake and the other strong earthquakes that occurred 
in Italy during the XX century basically comes from scientific and technical surveys. 
In contrast, the macroseismic data found in historical documents referring 
to earthquakes in some way are the best available sources of information on past 
seismicity before the end of XIX century. Macroseismic intensities are assigned 
based on distinct degrees of empirical scales, e.g., MCS and MSK; commonly, the 
uncertainty in intensity assignment is a half degree (Boschi et al., 1995). Thanks to 
the progress of historical studies in the last two decades, the information on historical 
seismicity in Italy and Europe has reached satisfactory levels of completeness 
and homogeneity, by means of procedures that allow verification of the research 
paths, the methods for data synthesis, and qualified elements for evaluating the 
data reliability. Such procedures and results are well illustrated in Stucchi (1993), 
Boschi et al. (1995) and Guidoboni and Ferrari (1995). It is essential to consider 
that macroseismic data, covering a wide time period, are influenced by the evolving 
social and cultural environments; therefore, also when they represent the best possible 
dataset, the description of the event may still be incomplete. Documents from 
state and local (church and municipal) archives (chronicles, letters, newspapers 
and reports by scientists and historians) provide two levels of information: general, 
giving information on the type, sometimes the size, and locality of the ground 
effect, or detailed information (from technical reports, projects), that provides the 
precise location (sometimes a map) and the size parameters, damage, occasionally 
also drawings or photographs, of the ground effect. Chiefly, sources contemporary 
or chronologically close to the event are considered and, subordinately, secondhand 
documents. Often, the multiplicity of sources allows one to cross-check the 
data. A reliability index defines the quality of each report. 

The earthquakes described in this study have been the subjects of at least a decade 
of researches and macroseismic analyses by the authors. In this way, numerous 
ground effects, such as landslides, ground fractures, surface ruptures (interpretable 
as coseismic faulting), liquefaction, soil settlements, features related to springs 
(appearance and disappearance, variation of discharge, muddied water and gas 
emissions, have been identified and mapped. Whenever possible, the recorded phenomena 
have been classified as primary (coseismic faulting) or secondary (induced 
by coseismic faulting or ground shaking) effects, based on air photo interpretation, 
field checking and paleoseismological analyses in trenches. The minimum distance 
of each secondary effect from the causative fault has been measured. For the 1980 
event, this distance is the actual space between each effect and the closest point 
of the surface trace of the ruptured fault, while for the 1805 event, as the actual 
earthquake fault trace is still not mapped in detail, the distance has been measured 
from the fault scarp at the base of the Matese Massif in the Bojano basin, which 
historical data and seismological and paleoseismological analyses have recognized 
as the most likely source of that earthquake (Michetti et al., 2000a). In the fol



AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 533 

lowing, all phenomena are named after the nearest village or town. Most locations 
of effects are precise (errors always smaller than 100 m) for the 1980 earthquake, 
having been mapped at 1:5,000 to 1:100,000 scales, whilst location errors may 
range from several tens of meters at best to 1–2 km for the 1805 event. 

The macroseismic field of the 1805 earthquake (Figure 2) was reconstructed 
by Esposito et al. (1987), based on the MCS scale. The coeval sources have been 
preferred, accessible in the state archives of Naples, Campobasso and Isernia, including 
reports by coeval scientists and priests, who directly witnessed this event 
(see Appendix I for the complete reference list). 

Documents stored in the archive of the Financial Ministry have proved extremely 
relevant, in particular the thick folder (more than 320 manuscripts) containing 
the correspondence between the State Secretary Luigi dé Medici and Gabriele 
Giannoccoli, that we would call now “Ministry for Civil Protection” (“avvocato 
fiscale”), who, immediately after the quake, was sent by King Ferdinando IV to 
survey the affected territory. Giannoccoli mailed daily reports describing the areas 
visited, the works in progress, and estimates of damage. He visited personally the 
most devastated area (about fifty localities), for the rest he based his reports on the 
descriptions of trusted collaborators and local administrators. Especially valuable 
was the work of the engineer, Luigi Marchese, who in addition to making surveys 
of damaged buildings and state of the road network, was also charged with making 
a detailed study of the territory of San Giorgio la Molara (Benevento district) where 
a large landslide had affected the land of the cardinal (Ruffo), destroying his mill. 

Many men of letters and scientific academicians were interested in the effects of 
the earthquake. Among them, the noble Gabriele Pepe, Saverio Poli, commander 
of the Royal Military Academy and member of the Royal Society of London, 
Pasquale Iadone, priest and professor of mathematics and philosophy, and Giuseppe 
Capozzi, priest and Royal academician, wrote careful monographs on the 
1805 event (Iadone, 1805; Pepe, 1806; Poli, 1806; Capozzi, 1834), where many 
data can be found to reconstruct the distribution of ground effects. These authors 
declare to have seen mainly the effects which provoked astonishing wonder in the 
people, crossing the land preferentially along the main itineraries (royal roads). 
Poli and Pepe visited more than 100 localities in the districts of Isernia, Campobasso, 
Avellino and Benevento, whereas Iadone described 28 localities in the 
district of Caserta. In several cases these authors singled out the different phases 
of occurrence of the effects (specially for the springs), before, during or after the 
seismic shaking. Numerous geological and hydrological effects were also faithfully 
reported in drawings (Esposito et al., 1987; Esposito et al., 1991; Esposito et al., 
1998). It is worth noting that at the time of this earthquake the territory was largely 
owned by noblemen and religious orders. Occupation and exploitation of land, i.e., 
agriculture and stock-raising, were higher than today. Nevertheless, although significant 
ground effects could hardly pass unnoticed, there cannot be any guarantee 
that all of them were reported, especially when there was no damage to roads or 
villages. 


S. PORFIDO ET AL. 
Figure 2. Geological-structural map of the study area (mainly after Mostardini and Merlini, 1986; 
Bonardi et al., 1988; Bigi et al., 1990, Michetti et al., 2000c). Legend: (1) Marine and continental 
sedimentary deposits present along the Tyrrenian margin, inside the tectonic depressions of the Apennines 
and in the Bradanic foredeep (Upper Pliocene – Quaternary); (2) Volcanic deposits related 
to the activity of the Tyrrhenian margin (Upper Pliocene – Quaternary); (3) Carbonate platform 
sequences of the Apulian Foreland (Upper Jurassic – Upper Miocene); (4) External foredeep and 
piggy-back deposits (Tortonian – Middle Pliocene); (5) Carbonate sequences of the Apennine platform 
structural unit (Upper Triassic – Miocene); 6) Carbonate-siliceous-marly deposits of the Molise 
and Lagonegro units (Upper Triassic – Miocene); (7) Slightly metamorphosed and metamorphosed 
basinal deposits and piggy-back deposits of the Internal units (Jurassic – Lower Miocene); (8) Quaternary 
normal fault; (9) Main overthrust; (10) Boundary of the allochthonous Apenninic units; (11) 
MCS Isoseismal lines of the 26 July 1805 earthquake (Esposito et al., 1987); (12) MSK isoseismal 
lines of the 23 November 1980 earthquake (Postpischl et al., 1985); 13) Epicentres of the 1805 and 
1980 earthquakes. Boxes show the borders of Figures 3 and 8. 

For the 1980 Irpinia event, a comprehensive revision of more than 100 papers 
and reports somehow referring to the geological phenomena associated to 
the earthquake (see reference list in Appendix I) and new specific studies on 
landslides distribution by air photo interpretation and field surveys (Esposito et 
al., 1997; Esposito et al., 1998) were carried out. The large number of technical 
surveyors and the detail of mapping scale assure that only a limited number of 


AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 535 

slides whose volumes exceeded a hundred cubic meters were left unnoticed. The 
accurate review, with new field surveys, air photo interpretation, geomorphological 
analyses and interviews with local witnesses (Blumetti et al., 2002), of the original 
unpublished field maps compiled during a field survey carried out immediately 
after the event by Carmignani et al. (1981), allowed a new interpretation of some 
ground breaks. As a matter of fact, these authors analyzed statistically the distribution 
of ground cracks, without a specific study of the tectonic and/or geotechnical 
significance of each fracture. 

A statistical analysis was carried out on the categories of secondary effects of 
the 1805 and 1980 earthquakes with a significant number of events: landslides, 
hydrological anomalies and liquefaction features. Most of the mapped landslides 
could be classified into four main types: rock fall, rotational slide, earth flow and 
slump-earth flow, according to Varnes (1978). 

In order to analyze the distribution of ground effects with distance and verify 
the occurrence of regularities, cumulative curves of the number of landslides, liquefaction 
features and hydrological anomalies vs. distance from the earthquake 
fault were prepared. Distances from faults of hydrological anomalies and liquefaction 
features were also plotted against macroseismic intensities, in order to try to 
visualize the relation between intensities, distance and number of effects. 

Some of the resulting parameters have been compared with the outcomes of 
comprehensive studies on the effects of recent historical earthquakes, such as (a) 
Keefer (1984), who provides statistics on the distribution of various types of landslides 
as a function of magnitude and maximum distance from the epicentre and 
the ruptured fault trace, based on 40 historical earthquakes distributed worldwide, 

(b) Ambraseys (1988), who analyses the known cases of liquefaction, and (c) 
Rodriguez et al. (1999), who integrate the work of Keefer with new data. 
3. Results and analysis 
3.1. EARTHQUAKES AND GEOLOGICAL SETTING IN SOUTHERN APENNINES 
The Apennines are a NW-SE-trending Neogene and Quaternary thrust and fold belt 
(Mostardini and Merlini, 1986; Patacca and Scandone, 1989; Doglioni et al., 1996). 
Since the Late Pliocene, following the opening of the Tyrrhenian sea (Cinque et 
al., 1991; Scandone et al., 1991), extensional tectonics progressively shifting to 
the East has produced a number of deep tectonic basins, hosting mainly marine 
deposits and volcanics on the Tyrrhenian side. In the inner sectors of the Apennines 
many intermountain basins have developed, typically as northwesterly elongated 
full graben, up to several tens of kilometers long, bounded by steep limestone 
slopes cut by normal faults, and hosting thick Quaternary continental sedimentation 
(e.g., in the study area, the Isernia, Bojano basins). The master faults dip 
prevalently South West, but North East in some basins, e.g., Bojano. A smoother 


S. PORFIDO ET AL. 
morphology characterises the eastern flank of the Southern Apennines, dominated 
by softer Mesozoic to Neogene silico-clastic deposits (Figure 2). 

Studies on active tectonics and paleoseismicity (Vittori et al., 1991; Pantosti et 
al., 1993; Michetti et al., 2000a; Michetti et al., 2000b) confirm that the present-day 
tectonic setting of the Southern Apennines is guided by a system of Quaternary normal 
faults, which determine a still immature basin-and-range morphology. These 
faults are responsible for frequent moderate to strong crustal earthquakes, with 
typical hypocentral depths of 7–20 km (Amato et al., 1997). Their slip-rates are 
of the order of several tenths of a millimeter per year, in good agreement with the 
historical and instrumental seismicity. 

3.2. THE 1805 EARTHQUAKE 
A disastrous earthquake hit the Molise region on 26 July 1805, damaging more 
than 200 localities and reaching its maximum destruction in Frosolone (Isernia 
district) where the peak intensity reached XI MCS (M 
= 6.8); more than 5000 
people died (Esposito et al., 1987). Several earthquakes with intensity I = 
XMCS 
affected the area in historical times before the 1805 event (Figure 1), in the years 
1349, 1456 and 1688 (CPTI, 1999). While their causative faults are still unknown, 
recent studies (Cucci et al., 1996, Guerrieri et al., 1999, Blumetti et al., 2002) 
have identified the master fault of the Bojano graben North East-verging) as the 
seismogenic structure responsible for the 1805 event. 

The Bojano basin is a tectonic depression (Figures 2 and 3) located between the 
Meso-Cenozoic Matese shelf-carbonatic ridge and pelagic carbonates and marls 
(Ferranti, 1994; Di Bucci et al., 1999; Guerrieri et al., 1999, and references therein); 
the basin is filled with more than 160 meters of lake, marsh, fluvial and alluvial 
fan sediments (GEMINA, 1963) overlying Neogene flysch deposits. Since the beginning 
of the Middle Pleistocene, the Bojano basin (and adjoining basins to the 
North West and South East) has been growing as a graben strictly related to the 
activity of a NW-SE trending system of synthetic and antithetic segmented faults 
defining a 30–40 km long regional tectonic structure (Corrado et al., 2000). Middle 
Pleistocene to Late Glacial geomorphological features (Guerrieri et al., 1999) are 
systematically displaced along bedrock fault scarps, suggesting a seismotectonic 
control on landscape evolution due to the activity of normal faults with slip-rates 
not smaller than 0.5 mm/yr. Furthermore, recent trench investigations along the 
northwestern segment of the Bojano fault system (Blumetti et al., 2002) have 
shown stratigraphic evidence of surface faulting in Holocene fan deposits related 
to at least two still undated seismic events, with Magnitude presumably above 6. 

The chronicles of the 1805 event describe at least 60 localities, generally concentrated 
within the area of VIII MCS (epicentral area), where the most significant 
ground effects occurred (Esposito et al., 1987; Esposito et al., 1991; Michetti et 
al., 2000a). Mostly, ground fractures, landslides and hydrological changes were 
recognized and classified, and only one case of liquefaction was registered. 


AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 537 


Figure 3. Epicentral area for the 26 July 1805 Molise event, showing the locations of ruptured fault segments and earthquake-induced ground effects. 


S. PORFIDO ET AL. 
Several reports contemporary to the earthquakes (Fortini, 1806; Pepe, 1806; 
Poli, 1806; Capozzi, 1834) described extensive ground ruptures with vertical displacements 
up to 1–1.5 m, in at least two localities, Morcone (Benevento district) 
and Guardiaregia (Isernia district) (Figure 3). A field check in these areas has 
revealed that they were generally aligned along the southwestern margin of Pleistocene 
continental basins (the most important of which is the Bojano basin), and 
occurred along prominent fault-generated mountain slopes, showing clear evidence 
for Holocene fault activity. Therefore, these fractures probably represent the reactivation 
of several northeast-dipping, Quaternary normal faults segments along the 
northeastern flank of the Matese Massif, for a total end-to-end rupture length of 
about 45 km (Figure 3). These segments belong to the system of capable faults 
(sensu Vittori et al., 1991; i.e., those active faults displaying evidence for recent 
displacement at or near the ground surface) that controlled the Quaternary evolution 
of the Bojano and nearby tectonically connected Isernia, Sepino and Morcone 
basins. 

Concerning the rupture length, a mutual triggering of consecutive fault segments 
is suggested by the occurrence, after the main shock at 21:01 GMT 
(Greenwich Mean Time), of two strong aftershocks before midnight. One had its 
epicentre in the village of Morcone (Benevento district); it produced moderate 
damage to the houses (I 
= VII MCS) and was felt in an area between Isernia 
and Naples. The second aftershock mainly affected the northeastern area of 
Isernia, with the maximum damage (I 
= VIII MCS) recorded in the village of 
Pescolanciano (Isernia district); it was felt over a large area between Rome and 
Naples. 

Definitely, the small number (26) of landslides identified and classified (Table 
I) cannot allow us to take this dataset as being complete. However, the earthquake 
occurred in July, which is normally a very dry period in peninsular Italy; 
in addition, coeval sources never mention rain, as commonly found in historical 
descriptions when rain preceded or followed an earthquake. This may contribute 
to explain the small number of triggered landslides compared to events of similar 
magnitude, such as the 1980 event and earthquakes in other regions of the world 
(Keefer, 1984). As stated above, given that landslides damaging roads or villages 
were certainly reported and the territory was much more densely inhabited at that 
time than today, the distribution of these effects in the epicentral area should be 
still usable for comparisons with other earthquakes. The main types were rock falls 
and rotational slides (Archivio di Stato di Napoli, Iadone, 1805, Pepe, 1806; Poli, 
1806; Esposito et al 1987; Esposito et al., 1991; Esposito et al., 1998). A large 
earth flow (several km2) occurred at Acquaviva d’Isernia (Isernia district), where a 
whole forest was destroyed (Pepe, 1806). Another big earth flow (about 5.5 km2) 
occurred in San Giorgio La Molara (Benevento district): it caused severe damage to 
some buildings and dammed a river valley, producing a temporary lake (Archivio 
di Stato di Napoli, 1805) (Figure 4). 


AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 539 


Figure 4. Map of the landslide induced by the 1805 earthquake in San Giorgio la Molara, drawn just after the event by an engineer. The document, dated1806 and located in the State Archive of Naples, provides the precise location and dimension of the landslide (3.7 km long and 1.5 km wide). 


S. PORFIDO ET AL. 
TABLE I 
Distribution of documented landslides by type for the earthquakes of 1805 and 
1980, compared with landslides distribution of 1857 and 1930 earthquakes. 

Type of slope failure 1805 1857 1930 1980 
earthquake earthquake earthquake earthquake 
(26 data) (39 data) (26 data) (199 data) 
(%) (%) (%) (%) 

Rock falls and topples 38.5 50 7.7 47.2 
Rotational slides 19.2 30 – 20.1 
Earth flows 11.6 2.5 23 3.5 
Slump-earth flows 3.8 7.5 19.2 20.1 
Undefined 26.9 10 50 9.1 

The distribution of the cumulative number of landslides vs. the minimum distance 
from the earthquake fault is given in Figure 5A. Most of the landslides 
(88.5%) occurred within a distance of 30 km; the rest of them took place within a 
distance of about 80 km. 

In particular, six slides (23.0% of the total, mostly rock falls) occurred in the 
epicentral area (0–10 km), distributed along the zone of coseismic faulting, and 
65% were between 10 and 30 km. Most landslides concentrated inside the intensity 
VII–X MCS isoseismal area. The maximum distance of a landslide from the 
epicentre was 114 km, and 82 km from the fault zone (town of Calitri, Avellino 
district), in a zone particularly susceptible to seismic shaking, as suggested by the 
regular occurrence of landslides after major earthquakes in the Southern Apennines 
(Porfido et al., 1991). 

In the surroundings of Cantalupo, within the Bojano basin (Figure 3), some 
typical signs of soil liquefaction, like small sand volcanoes, were also described in 
the historical sources (Poli, 1806). However, no other report of liquefaction features 
is available. 

Hydrological phenomena were numerous inside the macroseismic field (Figure 
3). They included increases in discharge rate of both springs and wells, muddied 
water, drying up of springs, or even new springs. Some variations in chemical 
parameters of the waters (temperature, colour, taste and smell) were observed at 
several locations, both inside and outside the epicentral area (Iadone, 1805; Poli, 
1806; Pepe, 1806). 

Significant hydrological variations (positive increase in discharge) were observed 
in Bojano (Campobasso district), where the Biferno spring flooded the 
village for about twenty days. This dramatic increase in the spring discharge rate 
has been interpreted by King and Muir-Wood (1993) as evidence of the deforma



AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 541 


Figure 5. Cumulative number of landslides vs. minimum distance from earthquake fault (see Table I). 

(A) 1805 earthquake: three landslides (11.5%) occurred at a distance >30 km. (B) 1857 earthquake: 
only one landslide occurred at a distance > 
30 km. (C) 1930 earthquake: four (15.3%) landslides 
occurred at a distance > 
30 km. Rotational slides were mapped as generic slides: a detailed study is 
in progress to better classify these slides. (D) 1980 earthquake: 35 landslides (17.5%) occurred at a 
distance > 
30 km. 
tion of major tectonic blocks. Most of the recorded hydrological phenomena were 
located in the Matese Massif, SSW of the epicentral area, which seems in good 
agreement with a causative earthquake fault dipping North East (King and Muir-
Wood, 1993). This is also suggested by the location of many coseismic ground 
ruptures close to recent northeast-facing bedrock fault scarps. To the North West 
and South East of the ruptured fault segment, diminishing discharge and even 
drying up of springs were observed (Esposito et al., 1987; King and Muir-Wood, 
1993). 

A scatter plot of intensity vs. distance from the earthquake fault for the 48 
identified hydrological variations (from 30 localities) is given in Figure 6A. Hydrological 
anomalies did not occur for intensities less than VI MCS. The cumulative 
distribution of the percentage of hydrological anomalies vs. the distance from the 
earthquake fault is shown in Figure 7A. The resulting trend is almost rectilinear 
up to a distance of 40 km, within which 87.5% of the effects took place. The rest 
of them were distributed out to a maximum distance of about 70 km (a well in 
Naples). 


S. PORFIDO ET AL. 
Figure 6. Hydrological anomalies: scatter plot of local macroseismic intensities vs. minimum 
distance from earthquake fault. (A) 1805 earthquake; (B) 1980 earthquake. 

3.3. THE 1980 IRPINIA–LUCANIA EARTHQUAKE 
The 1980 earthquake took place in the Irpinia-Lucania region, one of the most seismically 
active areas of the Southern Apennines. The structural setting of this region 
is characterised by a horst structure, made of two limestone blocks, Mt. Cervialto 
(1809 m a.s.l.) and Mt. Marzano (1530 m), split by the North-South trending upper 
Sele valley (Cinque et al., 1991). This horst is bounded to the North by the Ofanto 
valley graben, through a system of active normal faults dipping NNE and SSW 
(Michetti et al., 2000b). Such faults separate some minor horst structures from 


AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 543 


Figure 7. Cumulative number of hydrological anomalies vs. minimum distance from earthquake 
fault. (A) 1805 earthquake; (B) 1980 earthquake. 

the main range front, i.e., the Muro Lucano, Castelgrande and Santomenna ridges, 
reactivated during the 1980 event (Blumetti et al., 2002). The intermountain basins 
are filled with alluvial and lake deposits (e.g., Lioni basin), locally interleaved with 
the volcanic products of the now extinct Vulture volcano (0.8–0.5 ma) (Figures 2 
and 8). 

Unequivocal evidence for recent faulting has been proven only for a few Quaternary 
normal fault segments in this area. Most of them still await a detailed 
paleoseismic trench investigation. For instance, small tectonic depressions inside 


S. PORFIDO ET AL. 
the main limestone blocks, e.g., the Pantano di San Gregorio, connected to the 
fault strands reactivated during the 1980 earthquake, have provided paleoseismic 
evidence for repeated prehistoric seismic events (Pantosti et al., 1993). Holocene 
slip-rates at these sites are of the order of 0.2–0.4 mm/yr. However, this value 
should be considered as a minimum for the Irpinia seismogenic fault system, which 
has been the source of numerous disastrous events with intensity I 
= 
XMCS 
during historical times, in 989, 1694, 1930 and 1962 (Figure 1). Because these 
events are not recorded along the causative fault of the 1980 event (Pantosti et al., 
1993), their tectonic sources still await positive identification, and their slip-rates 
should be added to that of the 1980 fault. 

The Irpinia–Lucania earthquake of 23 November 1980 (Ms 
= 
6.9NEICNational 
Earthquake Information Center, and seismic moment M0 = 
26 × 
1018 
Nm, Westaway, 1993; epicentral intensity I0 = IX–X MSK – Medvedev Sponheuer 
Karnik scale, Postpischl et al., 1985) was the first event in the Apennines to undergo 
a systematic field and remote sensing mapping of seismically induced ground effects 
by independent investigators. The main shock took place at latitude 40.724.N 
± 
1.4 km and longitude 15.373.E ± 
1.4 km, its nucleation point was at 10–12 
km of depth (Westaway, 1993). The earthquake was a complex event, involving at 
least three distinct rupture episodes on different fault segments in a time span of 
approximately 40 s. The focal mechanisms suggest normal slip along North West-
South East striking planes, in good agreement with field evidence (Westaway and 
Jackson, 1987; Bernard and Zollo, 1989; Bernard et al., 1993). 

The earthquake heavily damaged more than 800 localities, mainly in the 
Campania and Basilicata regions, killing about 3,000 people (Postpischl et al., 
1985). It induced a widespread suite of geological effects including tectonic surface 
ruptures, soil cracks, landslides, deep-seated gravitational deformations and 
hydrological anomalies (Figure 8). 

Most of the many surface fractures were located within the area enclosed by 
the intensity VIII MSK isoseismal line, especially concentrated in the epicentral 
area (Carmignani et al., 1981). The surface fault ruptures, with mean strike North 
West-South East, dip 60. 
to the North East, and vertical offset ranging from 40 
to 100 cm (Westaway, 1993; Pantosti and Valensise, 1993), were related to the 0 
and 20 s sub events. More difficult was the identification of the fault responsible 
for the 40 s event, notwithstanding the comparable magnitudes (Mw 
= 6.2–6.5, 6.4 
and 6.3 for the 0, 20 and 40 s events, respectively, Westaway, 1993). This fault 
has been recently associated by Blumetti et al. (2002) with the ruptures (up to 20 
cm of normal slip, dip to South West) that occurred between Santomenna (Salerno 
district) and Muro Lucano (Potenza district), mapped just after the event as ground 
cracks by Carmignani et al. (1981). 

In total, 199 landslides were classified. Although there is no guarantee that such 
a database includes all the landslides that occurred because of the Irpinia seismic 
sequence (specially the small ones, without damage to houses or other infrastructure), 
it can be considered complete for phenomena having volumes of several 


AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 545 


Figure 8. Epicentral area for the 23 November 1980, event, showing the locations of ruptured fault segments and earthquake-induced ground effects (modifi edafter Esposito et al., 1998). 


S. PORFIDO ET AL. 
hundreds of cubic meters or more. The careful review of about 100 scientific papers 
concerning slope failures following the 1980 event and new specific studies (Esposito 
et al., 1998, and Appendix I) have permitted us to identify and characterize 
in detail most of the landslides in terms of type, location, dimension and damage. 
Many landslides were abrupt reactivations of already active or dormant slides 
and/or happened along slopes marked by preexisting events, making it difficult 
sometimes to discriminate their triggering earthquake mechanism. Some of these 
landslides had, and still have in some cases, dramatic effects on urban settlements 
(e.g., Agnesi et al., 1983; Carrara et al., 1986; Cotecchia, 1986; D’Elia et al., 1986; 
Del Prete, 1993). 

The volumes of the landslides were generally in the range of hundreds to millions 
of cubic meters (one of the largest was in Calitri, Avellino district, where 23 
million cubic meters of rock slid down, caused enormous damage to the town). 
Big rock falls, occurred in the epicentral area, having volumes ranging from 100 
to 10,000 m3 (Carrara et al., 1986). Most of the landslides were caused by the 
inertial forces induced by seismic shaking. Table I shows the distribution of mass 
movements by type. Rock falls were the most numerous and typically occurred 
during seismic shaking inside the epicentral area. Only a limited number of rotational 
landslides occurred outside the VI MSK isoseismal; these were within the 
V MSK out to a distance of about 100 km (97 km in the case of Ailano, Caserta 
district), and 91 km from Ferrandina, Matera district, due to conditions of preexisting 
precarious equilibrium and were delayed up to 240 hours after the main 
shocks (Del Prete et al., 1992). 

The mapped landslides were distributed over an area of 22,000 km2 (Esposito et 
al., 1997b). Such an area fits well the curve for magnitude proposed by Rodriguez 
et al. (1999). However, the number of slides vs. this surface area is low compared 
to other earthquakes in the world (Keefer, 1984; Rodriguez et al., 1999). The landslide 
distribution vs. distance from the ruptured fault segment (Figure 5D) shows 
that most of them (81.4%) occurred within a distance of 30 km; the percentage 
of mapped landslides (13%) decreases very rapidly with distance between 30 and 
60 km. Isolated phenomena (5%) were observed up to distances of nearly 100 km. 
For comparison, after the 1989 Loma Prieta earthquake (Ms 
= 
7.1), rock falls 
and other highly disruptive landslides larger than about 100 cubic meters were 
restricted to distances not exceeding 10 km from the fault (Keefer and Manson, 
1998). 

Concerning liquefaction, 21 phenomena (in 16 localities) were recognized and 
classified (Galli, 2000). The relationship between number of events and the distance 
from earthquake fault segment (Figures 9A, B) shows that 80% of them 
occurred within 30 km, and 20% between 30 and 60 km. No events occurred more 
than 60 km from the fault. No liquefaction cases were reported in areas of intensity 
less than VI MSK. 

To evaluate the hydrological effects produced by the earthquake within the macroseismic 
field, the variation of water level in 9 selected wells, about 50 stream flow 


AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 547 


Figure 9. Liquefaction cases induced by the 1980 earthquake: (A) Cumulative number of liquefaction 
cases vs. the distance from earthquake fault; (B) Scatter plot of local macroseismic intensity vs. the 
liquefaction distance from earthquake fault. 

gauging stations and 70 important (discharge rate > 
55 l/s) springs was analyzed, 
identifying 35 anomalies (Esposito et al., 2001). All the river gauging stations registered 
a distinct increase in water flow. As a rule, the overall period of hydrologic 
anomaly did not exceed 48–72 h. 

Eight springs, mainly located in the Upper Sele Valley and in the Mt. Matese 
region, displayed a distinct hydrological anomaly. On the whole, a general increase 
of discharge was observed for a period of 6 to 12 months after the event (Cotecchia 
et al., 1986b; Onorati et al., 1994; Esposito et al., 1999). 


S. PORFIDO ET AL. 
Figure 10. Plot of the maximum distances from the fault of the three main types of landslide induced 
by the 1805, 1857, 1930 and 1980 earthquakes. All the values are in good agreement with the 
upper-bound envelope curves proposed by Keefer (1984). 

A scatter plot of local macroseismic intensity vs. distance from the earthquake 
fault for the 35 identified hydrological variations (from 34 localities) is given in 
Figure 6B. Hydrological anomalies occurred for intensities as low as IV MSK. 
The cumulative distribution of the percentage of hydrological anomalies vs. the 
distance from the earthquake fault is shown in Figure 7B. The resulting trend is 
almost rectilinear up to a distance of about 130 km, within which 87.5% of the 
effects took place. The remainder are distributed out to a maximum distance of 

187.5 km. Therefore, the 1980 Irpinia earthquake activated several major hydrogeological 
structures, corresponding to the main Apenninic carbonate massifs from 
the Abruzzo-Molise (North West) to the Basilicata (South East) regions. 

AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 549 

4. Discussion 
The 1805 Molise and 1980 Irpinia–Lucania earthquakes were accompanied by 
coseismic dip-slip surface faulting and a large number of secondary geological 
effects, including landslides, ground cracks, liquefaction and variations in the discharge 
rate of major carbonate springs. Historical data and paleoseismological 
analyses have allowed mapping only short segments of the actual earthquake fault 
trace of the 1805 event, which are located along the fault at the base of the northeastern 
slope of the Matese Massif in the Bojano-Morcone basin (Michetti et al., 
2000a). Thus, the portion of this fault running from just North of Isernia (Miranda) 
to at least Morcone (Figure 3) is the most likely source of this earthquake. 
The path of the main 1980 fault rupture (dipping North East) at first surprised 
geologists for its poor morphological evidence, but was later traced in detail by 
Westaway and Jackson (1987) and Pantosti and Valensise (1993), who recognized 
the repetition of several coseismic faulting events during the Holocene. Another 
surface rupture (dipping South West) accompanied the 40 s event (Blumetti et al., 
2002). Surface fault ruptures of both events followed the traces of already existing 
Quaternary capable normal faults with distinctive geomorphic expressions, such as 
Pleistocene intermountain basins in their hanging walls (1805 event and likely 40 s 
event in 1980), fault-generated carbonate slopes, bedrock fault scarps and recent 
tectono-karstic basins (Michetti et al., 2000c). 

Both earthquakes were characterized by complex rupture mechanisms, involving 
the reactivation of several segments aligned WNW-ENE within a very 
short time interval. The total rupture length, based on a field survey for the 1980 
event and historical sources and modelling for the 1805 event, was in the range 
of 40 km, which is in good agreement with the worldwide data for that range of 
magnitude (Wells and Coppersmith, 1994; Esposito et al., 1997a). 

The types of landslides triggered by these earthquakes were primarily controlled 
by the stratigraphy and tectonic setting of the areas struck. In general, landslides 
occurred on slopes typically showing evidence of recurrence of similar phenomena, 
and were represented mainly by rock falls, rotational slides and slump-earth flows, 
and rapid earth flows. Rock falls were widespread (47.2%) for the 1980 event 
(Table I), due to the rugged topography in the epicentral area, with steep slopes 
made of highly fractured carbonate rocks. Regarding the 1805 event, although the 
number of recorded phenomena is much smaller (26), this has presented a unique 
opportunity to study the types of slides for an event that occurred two centuries 
ago and to compare their distribution with that of the well studied 1980 event in 
the same tectonic environment. The percentages of landslide types are comparable 
(Table I); rock falls were widespread (38.5%), probably because the North East 
sector of the epicentral area includes relatively soft silico-clastic deposits (Figure 
2). 

The landslide distribution is quite similar to the general pattern of the isoseismal 
distribution, showing a concentration of the mass-movements in the areas of 


S. PORFIDO ET AL. 
greatest intensity, and their progressive reduction in density with distance from the 
epicentre. Most of the slides were confined within an area of about 15,000 km2 
for the 1805 event, and about 22,000 km2 for the 1980 event. This agrees with 
the relationship between area affected by landslides and earthquake magnitude 
proposed by Rodriguez et al. (1999), especially for multiple seismic events, which 
predicts an area slightly larger than that proposed by Keefer (1984). 

Figures 5A and 5D show the cumulative distribution of landslides vs. the distance 
from the causative fault for the 1805 and 1980 events. For the latter, more than 
50% of landslides occurred within a distance of 10 km, whereas for both events 
80% of landslides occurred within a distance of 20 to 30 km. The distances of the 
furthest landslides for the 1805 and 1980 events were 82 and 97 km, respectively. 
The area of maximum density overlaps that of maximum damage, classified as 
intensity VII to X MCS. It is interesting to note that the best fit exponential curves 
for these two earthquakes have similar exponents. For comparison, also the data 
available for the earthquakes of 1857 in Val d’Agri (I 
=X–XIMCS, M 
=6.9; 
CPTI, 1999) and 1930 in Irpinia (I 
=X MCS, M 
= 6.7; CPTI, 1999) are shown 
in Figures 5B and 5C and in Table I. The numbers of known landslides are 39 
and 26, respectively (Esposito et al., 1998; Esposito et al., 2000). The cumulative 
curves show a similar distribution of percentages with distance, but no phenomena 
are known beyond about 50 km. The exponents of the best fit exponential curves 
are a little higher in absolute value than those of A and D. It should be noted that 
the 1930 event occurred in a relatively dry period and its epicentral area was at the 
eastern border of the Apennines, where the relatively soft materials are less prone 
to rock falls, the most common type of slope failure in the epicentral area of the 
other events. 

It is also noteworthy that the maximum distances from the fault of the three 
main types of mapped landslides (rock falls, coherent slides and earth flows) for 
the four earthquakes fall within the envelope curves for magnitude proposed by 
Keefer (1984). 

The liquefaction data for the 1980 event well fit the maximum epicentral distance 
vs. magnitude envelope curves of Keefer (1984), Ambraseys (1988) and 
Rodriguez et al. (1999) (Figure 11). Most liquefaction events occurred within 
the isoseismal VIII MSK. The maximum distance from the fault was 55 km and 
minimum intensity VI MSK (Galli, 2000). 

The graphs of the cumulative percentage of hydrological anomalies vs. the 
minimum distance from the fault (Figure 7) display both an almost linear decay 
for nearly 90% of the data, the 1805 earthquake up to a distance of 40 km, and 
the 1980 event up to a distance of nearly 130 km, with an abrupt flattening of the 
curves at higher distances. The farthest recorded anomaly occurred 187 km away 
from the 1980 fault, where the surface shaking was almost negligible, suggesting 
that the rupture mechanism had a strong influence on deep circulation. According 
to King and Muir-Wood (1993), the mechanisms causing the observed hydrological 
changes in both earthquakes depended essentially on the style of faulting. In partic



AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 551 


Figure 11. Maximum epicentral distance of spreads and flows as function of magnitude Ms.The 
solid line shows the upper bound envelope curve obtained by Keefer (1984); the dashed line shows 
the liquefaction bound proposed by Ambraseys (1988). The data for the 1805 and 1980 earthquakes 
are compared with 15 more events proposed by Rodriguez et al. (1999): 1– Irpinia 1980 Italy; 3 – 
Borah Peak 1983 USA; 4 – Nagoken-Seibu 1984 Japan; 7 – San Salvador 1986 El Salvador; 9 – 
Edgecumbe 1987 New Zealand; 18 – Loma Prieta 1989 USA; 20 – Luzon 1990 Philippines; 21 – 
Valle de la Estrella 1991 Costa Rica; 22 – Erzincan 1992 Turkey; 24 – Suusamyr 1992 Kyrgyzstan; 
26 – Hokkaido-Nansei 1993 Japan; 29 – Klamath Falls 1993 USA; 30 – Northridge 1994 USA; 31 – 
Paez 1994 Colombia; 33 – Hyogu-ken Nanbu 1995 Japan. 

ular, the type and distribution of hydrological variations fit well a normal faulting 
mechanism. Data on hydrological anomalies are more abundant and widespread 
for the 1805 earthquake than for the 1980 one (Figures 3 and 8). Nevertheless, the 
1980 event affected aquifers about 200 km away from the fault, and the 1805 event 
about 70 km away (Figures 6 and 7). Even taking into account the better accuracy 
of the research conducted after the 1980 event, such a strong influence of the Irpinia 
earthquake on the hydrogeological structure of the Southern Apennines still needs 
a satisfactory explanation. 

5. Conclusions 
The three main types of ground effects considered in this study focused in the 
epicentral-macroseismic areas of the 1805 and 1980 earthquakes; these effects occurred 
at different minimum thresholds of intensity and out to different distances: 
landslides for intensities as low as V MCS/MSK and distances out to 100 km, 
liquefaction for minimum intensity VI MSK and shorter distances (55 km at Sca



S. PORFIDO ET AL. 
fati, Salerno district). By contrast, hydrological changes occurred almost 200 km 
away from the fault zone, where the intensity was about IV. This may suggest that 
aquifers are more sensitive to seismic shaking than other effects. Nevertheless, it 
would probably be necessary to better explore this susceptibility to earthquakes 
further, and the seismotectonic deformation of aquifers hosted in wide carbonate 
bodies apparently far from each other (Kresic, 1997; Ingebritsen and Sanford, 
1999). 

The modern, relatively well-studied, 1980 earthquake and the historical, 1805 
earthquake show striking analogies, both in the overall pattern of coseismic geological 
phenomena and in the details of ground effects. It can be observed that 
the distances of surface effects of these two strong earthquakes from the causative 
fault did not exceed 4 times the length of the ruptured fault zone for hydrological 
anomalies and three times the length for landslides and liquefaction. 

The study of the geological phenomena induced by great earthquakes provides 
basic information for the characterization of seismic hazards (USGS, 1999). Even 
if the type and relevance of surface effects strongly depend on the local geomorphological 
setting, their characterization allows for a realistic estimation of 
the earthquake source parameters, and for a proper evaluation of the vulnerability 
of the environment in the presence of significant releases of seismic energy. 
The satisfactory results of this study encourage a continuation of the search for 
relationships among ground effects, intensities and fault parameters, starting from 
other historical strong earthquakes in the Southern Apennines, within the same 
lithologic, geomorphic and tectonic environment. During strong historical earthquakes 
in the Southern Apennines, primary and secondary ground effects tend to 
concentrate within Pleistocene to Holocene intermountain tectonic basins. As a 
matter of fact, because primary and secondary ground effects are typical morphogenetic 
components of the seismicity of an area, such a study will be fundamental 
for properly assessing the characteristic seismic landscapes (sensu Serva, 1995; 
Michetti and Hancock, 1997) and, therefore for forecasting the most likely future 
seismic magnitude and pattern of geological effects for the different “seismically 
homogeneous” sectors of the Apennines. 

Acknowledgments 

We are indebted to the editors of this Special Issue and the two anonymous referees 
for their careful reading of the manuscript and their many suggestions. 


AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 553 

Appendix I 

SUMMARY OF CONTRIBUTIONS ON 23 NOVEMBER 1980 
EARTHQUAKE-INDUCED LANDSLIDES 

Abbate, E., Borrelli, V., Cornaggia, F., Ferrini, G., Pandeli, E., Pranzini, G., Principi, G.: 1983, 
Comune di Rocca S. Fe1ice (AV). Indagini di microzonazione sismica. Intervento urgente in 39 
centri abitati della Campania e Basilicata colpiti dal terremoto del 23 Novembre 1980, CNR-PFG 
Pubbl. 492. 

Agnesi, V., Carrara, A., Macaluso, T., Monte-Leone, S., Pipitone, G., Sorriso-Valvo, M.: 1982, Osservazioni 
preliminari sui fenomeni di instabilityà dei versanti indotti dal sisma del 1980 nell’alta 
Valle del Sele, Geologia Applicata e Idrogeologia XVII, 79–93. 

Autori vari: 1983, Indagini di Microzonazione Sismica – Intervento urgente in 39 centri abitati della 
Campania e Basilicata colpiti dal terremoto del 23 Novembre 1980, CNR-PFG Pubbl. 492. 

Baldassarre, G.: 1981, Effetti geologici del sisma del 23-11-80 nella periferia dell’abitato di Atella 
(PZ) (Basilicata), Geologia Applicata e Idrogeologia XVI. 

Baldassarre, G., Radina, H.: 1982, Note sulle condizioni di instabilità di alcuni tracciati stradali in 
Basilicata, Geologia Applicata e Idrogeologia XVII, parte I, 385–404. 

Battista, C., Pennetta, L., Romenazzi, L.: 1986, A preliminary analysis of failures around the built-up 
area of Calabritto, Irpinia, activated by the earthquake of November 23, 1980, Geologia Applicata 
e Idrogeologia XXI, parte II. 

Biasini, A., Landini, B.: 1981, Dissesti in atto e potenziali da aerofotografie del 1979 Monti Picentini 
(Campania), Rendiconti Società Geologica Italiana 4, 151–154. 

Bollettinari, G., Carton, A., Salmi, M., Esposito, E., Panizza, M., Petrini, V.: 1983, Comune di 
S.Gregorio Magno (SA). Indagini di microzonazione sismica. Intervento urgente in 39 centri abitati 
della Campania e Basilicata colpiti dal terremoto del 23 Novembre 1980, CNR-PFG Pubbl. 492. 

Bollettinari, G., Esposito, E., Gasperi, G., Panizza, M., Rizzo, V., Petrini, V., Solmi, M.: 1983, 
Comune di Balvano (PZ) – microzonazione sismica preliminare. Indagini di microzonazione sismica. 
Intervento urgente in 39 centri abitati della Campania e Basilicata colpiti dal terremoto del 
23 Novembre 1980, CNR-PFG Pubbl. 492. 

Bousquet, J.C., Oars, O., Lanzafame, O., Philip, H.: 1983, Ruptures de surface d’origine gravitationnelle 
lors du seisme de l’Irpinia (23-11-1980; Italie Meridionale), Geologia Applicata e 
Idrogeologia XVIII, parte I, 427–435. 

Bozzano, F., De Pari, P., Gambino, P.: 1995, Instabilità dei versanti nell’area di S. Angelo dei 
Lombardi–Alta valle del F. Ofanto, IV Conv. Naz. dei Giovani Ricercatori: Gruppo Nazionale 
di Geol. Appl, Riccione, 18–21 Ottobre 1994, Quaderni di Geologia Applicata (CNR-GNDCI) I, 
Pitagora Editrice, Bologna. 

Budella, P., Calcaterra, D., De Riso, R., Santo, A.: 1990, Geologia e Fenomeni franosi dell’alta valle 
del Fiume Ofanto (Appennino Meridionale), Memorie Società Geologica Italiana 45, 309–324. 

Budetta, P.: 1982, Geologia e frane dell’ Alta Valle del F. Sele (Appennino Meridionale), Memorie e 
Note dell’Istituto di Geologia Applicata Napoli XVI. 

Calcagnile, G., Canziani, R., Del Gaudio, V., Guerricchio, A., Melidoro, G., Ruina G.: 1983, Indagini 
geologico-geofisiche in alcune aree franose di Avigliano e di Stigliano (Basilicata), Geologia 
Applicata e Idrogeologia XVIII,parte I. 

Calcagnile, G., Canziani, R., Del Gaudio, V., Ruina G., Ziccarelli, L.: 1985, Indagini geofisiche in 
alcune aree interessate dal sisma del 23 Novembre 1980 (indagini preliminari), Geologia Applicata 
e Idrogeologia XX, parte 11, 449–452. 

Calcagnile, G., Melidoro, G., Panza, G.F., Salviola, O.: 1978, Studio introduttivo alla correlazione 
fra movimenti franosi e attività sismica nell’ Appennino Centro-Meridionale, Geologia Applicata 
e Idrogeologia XIII, 159–184. 


S. PORFIDO ET AL. 
Cantalamessa, G., Dramis, F., Pambianchi, G., Romeno, A., Santoni, A. M., Tonnetti, G.: 1981, 
Fenomeni franosi connessi con attività sismica nell’area compresa tra S. Giorgio La Molara e 
Bisaccia, Rendiconti Società Geologica Italiana 4, 467–469. 

Cantelli, C., Ferrari, G., Postpischl, D., Raffagli, A., Torri, G., Zarri, F.: 1983, Comune di Vietri 
di Potenza (PZ). Indagini di microzonazione sismica. Intervento urgente in 39 centri abitati della 
Campania e Basilicata colpiti dal terremoto del 23 Novembre 1980’, CNR-PFG Pubbl. 492. 

Carulli, G.B., Migliacci, A., Onofri, R., Porfido, S.: 1981, Indagini geologiche ed ingegneristiche in 
prospettiva sismica a S. Michele Di Serino (AV), Rendiconti Società Geologica Italiana 4, 161– 

164. 
Carulli, G.B., Migliacci, A., Onofri, R., Porfido, S.: 1983, Comune di Solofra (AV). Indagini di 
microzonazione sismica. Intervento urgente in 39 centri abitati della Campania e Basilicata colpiti 
dal terremoto del 23 Novembre 1980, CNR-PFG Pubbl. 492. 

Catenacci, V.: 1992, Il dissesto geologico e geoambientale in Italia dal dopoguerra al 1990, Memorie 
descrittive della Carta Geologica d’ltalia XLVII, Ist. PoI. E Zecca dello Stato, Rome. 

Cestari, G.: 1986, Effetti del sisma del 23-11-80 sulla stabilityà dei versanti del Cilento Settentrionale 
(1. 
nota), Geologia Applicata e Idrogeologia XXI, parte I, 37–52. 

Cherubini, C., Guerricchio, A., Melidoro, G.: 1981, Un fenomeno di scivolamento profondo delle 
argille grigio-azzurre Plio-Calabriane nella Valle del T. Sauro (lucania) prodotto dal terremoto del 
23 Novembre 1980 – nota preliminare, Rendiconti Società Geologica Italiana 4, 155–159. 

Chiocchini, U., Cherubini, C.: 1986, Seismic microzoning of the Lioni village destroyed by the 
November 23rd 1980 earthquake (Irpinia, Campano-Lucano Apennine), Geologia Applicata e 
Idrogeologia XXI, parte III. 

Chiocchini, U., Cipriani, N.: 1986, Seismic microzoning to rebuild Caposele village destojed by 
the November 23, 1980 earthquake (Irpinia, Campano-Lucano Apennine), Geologia Applicata e 
Idrogeologia XXI, parte III. 

Cotecchia, V.: 1981, Relazione sui problemi geomorfologici, idrogeologici e geotecnici evidenziatisi 
nel territorio colpito dal sisma Campano-Lucano del 23 Novembre 1980 e proposte di intervento 
del Sottoprogetto “Fenomeni Franosi” P.F. “Conservazione del Suolo” del C.N.R) per lo studio 
delle situazioni d’instabilità dei versanti, finalizzato all’opera di ricostruzione e di utilizzazione 
dell’area disastrata’, CNR P.F. “Conservazione del suolo”, Univ. di Bari, gennaio 1981. 

Cotecchia, V.: 1981, Considerazioni sui problemi geomorfologici, idrogeologici e geotecnici evidenziatisi 
nel territorio colpito dal sisma Campano-Lucano del 23 Novembre 1980 e possibilità 
di intervento del Progetto Finalizzato “Conservazione del Suolo” del CNR, Rendiconti Societá 
Geologica Italiana 4, 73–102. 

Cotecchia, V.: 1982, Phenomena of ground instability produced by the earthquake of November 23, 
1980 in Southern Italy, 4th International Congress I.A.E.G., 10–15 Dec., New Delhi, India, theme 
6, 1–14. 

Cotecchia, V.: 1984, Note sui fenomeni d’instabilità del territorio e sulla loro rappresentazione con 
particolare riguardo agli eventi sismici. Lineamenti di geologia regionale e tecnica delle aree colpite 
dal terremoto del 23 Novembre 1980, FORMEZ-Napoli, 207–290. 

Cotecchia, V., Del Prete, M.: 1984, Reactivation of large flows in the part of Southern Italy affected 
by the earthquake of November 1980, with reference to evolutive mechanism, IV Int. Symp. on 
Landslides, Toronto. 

Cotecchia, V., Del Prete, M.: 1986, Some observations on stability of old landslides in the historic 
centre of Grassano after the earthquake of 23 November 1980, Geologia Applicata e Idrogeologia 
XXI, 155–167. 

Cotecchia, V., Del Prete, M., Federico, A., Fenelli, B.G., Pellegrino, A., Picarelli, L.: 1986, Studio 
di una colata attiva in formazioni strutturalmente complesse presso Brindisi di Montagna Scalo 
(Potenza), Geologia Applicata e Idrogeologia XXI. 


AREAL DISTRIBUTION OF GROUND EFFECTS INDUCED BY STRONG EARTHQUAKES 555 

Cotecchia, V., Del Prete, M., Tafuni, N.: 1986, Effects of earthquake of 23 November 1980 on preexisting 
landslides in the Senerchia area (Southern Italy), IV Int. Symp. on Engineering geology 
problems in seismic areas, Bari, pp. 177–198. 

Cotecchia, V., Del Prete, M., Tafuni, N.: 1986, Effects of earthquake of 23 November 1980 on preexisting 
landslides in the Senerchia area (Southem Italy), Geologia Applicata e Idrogeologia XXI, 
parte IV, Bari. 

Cotecchia, V., Lenti, V., Salvemini, A., Spilotro, G.: 1986, Reactivation of large “Buoninventre” slide 
by irpinian earthquake of 23 November 1980, I.A.E.G., Proceeding of the International Symposium 
on “Engineering Geology Problems in Seismic Areas”, Bari, 13–16 Aprile, 3. 

Cotecchia, V., Luongo, G., Pagliarulo, R., Salvemini, A., Santagatti, G., Ventrella, N.A.: 1986, 
Excursion Guidebook (Post Symposium Tecnical Tour) I.A.E.G., Proceeding of the International 
Symposium on “Engineering Geology Problems in Seismic Areas”, Bari, 13–16 Aprile, 6. 

Cotecchia, V., Monterisi, L., Salvemini, A.: 1986, Effects of the November 23, 1980 earthquake 
on the Conza della Campania Dam and on its supplemental structures, Geologia Applicata e 
Idrogeologia XXI, parte IV, 363–393. 

Cotecchia, V., Monterisi, L., Salvemini, A., Ventrella, N.A.: 1986, Analysis of mass movement that 
occurred during construction of Conza Dam (Avellino – Southem Italy) on Ofanto River, Geologia 
Applicata e Idrogeologia XXI, parte IV, 199–216. 

Cotecchia, V., Nuzzo, G.: 1986, Hydrological study of the upper valleys of the Sele and Ofanto 
Rivers struck by the November 23, 1980 earthquake. Historical period of the survey: 1928–1979. 
Reference years: 1980–1981, Geologia Applicata e Idrogeologia XXI, parte IV, 65–95. 

Crescenti, U., Dramis, F., Gentili, B., Praturlon, A.: 1984, The Bisaccia landslide: a case of deep 
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terrains, Communications du Colloque, 22–24 Mars, Caen, 14–21. 

Dalla Giovanna, G., Marchetti, G., Corsanego, A., Papani, G., Petrucci, F., Tellini, C., Vernia, L., 
Augusti, V., Capurro, M., Stura, D., Logiudice, E., Sorriso-Valvo, M.: 1983, Comune di Caposele 
(AV). Indagini di microzonazione sismica. Intervento urgente in 39 centri abitati della Campania e 
Basilicata colpiti dal terremoto del 23 Novembre 1980, CNR-PFG, Pubbl. 492. 

D’Elia, B.: 1983, La stabilità dei pendii naturali in condizioni sismiche, A.G.I. XV Convegno 
Nazionale di Geotecnica 4–6 Maggio Spoleto, 125–135. 

D’Elia, B.: 1992, Dynamic aspects of a landslide reactivated by the November 23, 1980 Irpinia 
earthquake (Southern Italy), Proceedings of the French-Italian Conference on slope stability in 
seismic areas, May 14–15, Bordighera (Imperia), Italy, pp. 25–32. 

D’Elia, B., Federico, G., Pescatore, T., Rippa, F.: 1986, Occurrence of a large landslide (Andretta – 
Italy) reactivated by the November 23, 1980 earthquake, Geologia Applicata e Idrogeologia XXI, 
365–381. 

Del Prete, M.: 1981, Alcuni problemi geologici e geotecnici per la ricostruzione nelle zone colpite 
dal sisma del 23-11-1980, Atti e Relazioni dell Accademia Pugliese delle Scienze XXXIX, parte II, 
3–12. 

Del Prete, M.: 1981, La frana del centro storico di Grassano: meccanismo, età, effetti del terremoto 
del 23-11-1980, Rendiconti Società Geologica Italiana 4, 169–172. 

Del Prete, M.: 1990, Examples of mudslides hazard in southern Apennines (Italy), Atti Convegno 
“Irpinia dieci anni dopo”. 

Del Prete, M.: 1992, Frane per colamento e loro effetti nelle aree dell’appennino centro-meridionale’, 
In A. Vallario, 1992, Frane e territorio Liguori Editore, Napoli. 

Del Prete, M., Bentivenga, M., Favia, E., Modugno, L., Summa, V.: 1990, Movimenti franosi nelle 
aree sismiche della Basilicata, della Puglia e dell’Irpinia, Atti del Convegno GNDT I, 435–442. 

Del Prete, M., Chiocchini, V., Palmentola, G.: 1981, Excursion Guidebook, Atti della Conferenza 
Internazionale sulle zone sismiche dell’area mediterranea, Matera, 373–386. 


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Del Prete, M., Trisorio-Liuzzi, G.: 1981, Risultato dello studio preliminare della frana di Calitri 
(AV) mobilitata dalla scossa sismica del 23.11.80, Geologia Applicata e Idrogeologia XVI,parte 
II, 153–166. 

Esposito, E., Luongo, G., Marturano, A., Porfido, S.: 1989, Terremoti ed effetti superficiali. Esempi 
di ricorrenze sistematiche. Conferenza annuale scientifìca sulle attività di ricerca dei dipartimenti, 
Università di Napoli Dip. Geofisica-Vulcanologia, 126–127. 

Faccioli, E., Siro, L.: 1983, Comune di Muro Lucano (PZ) – microzonazione sismica preliminare. 
Indagini di microzonazione sismica. Intervento urgente in 39 centri abitati della Campania 
e Basilicata colpiti dal terremoto del 23 Novembre 1980, CNR-PFG, Pubbl. 492. 

Faccioli, E., Siro, L.: 1983, Comune di Castelgrande (PZ) – microzonazione sismica preliminare. 
Indagini di microzonazione sismica. Intervento urgente in 39 centri abitati della Campania e 
Basilicata colpiti dal terremoto del 23 Novembre 1980, CNR-PFG, Pubbl. 492. 

Faccioli, E., Siro, L.: 1983, Comune di Pescopagano (PZ). Indagini di microzonazione sismica. 
Intervento urgente in 39 centri abitati della Campania e Basilicata colpiti dal terremoto del 23 
Novembre 1980, CNR-PFG, Pubbl. 492. 

Fenelli, G.B., Picarelli, L., Silvestri, F.: 1992, Deformation process of a hill shaken by the Irpinia 
earthquake in 1980, Proceeding of the French–Italian Conference on Slope Stability in Seismic 
Areas, May 14–15, Bordighera (Imperia), Italy, 47–62. 

Genevois, R., Prestininzi A.: 1982, Deformazioni e movimenti di massa indotti dal sisma del 23-111980 
nella media Valle del F. Tammaro (BN), Geologia Applicata e Idrogeologia XVII, 305–317. 

Grassi, D., Merenda, L., Sdao, F.: 1988, Esempi di fenomeni gravitativi di diverso tipo nell’ 
Appennino Campano-Lucano, Memorie Società Geologica Italiana 41, 897–904. 

Guelfi, G., Monforti, E., Bozzo, E., Gallianai, Plesi, O.: 1983, Comune di Conza della Campania 
(AV) – microzonazione sismica preliminare. Indagini di microzonazione sismica. Intervento urgente 
in 39 centri abitati della Campania e Basilicata colpiti dal terremoto del 23 Novembre 1980, 
CNR-PFG, Pubbl. 492. 

Guerricchio, A., Melidoro, G.: 1981, Movimenti di massa pseudo-tettonici nell’ Appennino 
dell’Italia Meridionale, Geologia Applicata e Idrogeologia XVI, 251–294. 

Guerricchio, A., Melidoro, G.: 1982, New views on the origin of badlands in the Plio-Pleistocenic 
clays of Italy, Proceedings 4th International Congress. I.A.E.G., 10–15 Dec., New Delhi, India, II, 
theme I: 227–236. 

Guerricchio, A., Melidoro, G.: 1988, Fenomeni franosi dell’ abitato di Stigliano (Basilicata), 
CNR-GNDCI, linea 2, Riunione sul monitoraggio dei fenomeni franosi e sulle tecniche di 
rappresentazione cartografica, Bologna, pp. 43–63. 

Guida, M., Iaccarino, G.: 1984, Evoluzione dei versanti e franosità, Ricerche e Studi FORMEZ 36, 
75–98. 

Hutchinson, J. N., Del Prete, M.: 1985, Landslides at Calitri, Southern Apennines, reactivated by the 
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Iaccarino, G., Ianniello, G.: 1993, Carta delle frane del Comune di Tito, Carta inedita allegata al 
Piano Regolatore Generale del Comune di Tito. 

Iaccarino, G., Paparo Filomarino, M., Pellegrino, A., Picarelli L.: 1986, Bisaccia hill and its stability, 
Int. Symp. on Engineering Problems in Seismic Areas, Bari. 

Lazzari, S.: 1986, Criteri e tecniche di intervento per la tutela e la protezione dei centri urbani 
della Basilicata interessati da movimenti franosi, A.G.I. XVI Convegno Nazionale di Geotecnica, 
Bologna 14–16 Maggio, pp. 91–100. 

Lazzari, S., Annovi, A., Martini, E.: 1988, Il problema del consolidamento e del trasferimento degli 
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Maggiore, M.: 1981, Evidenze di movimenti connessi col terremoto del 23-11-1980 lungo faglie 
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Maggiore, M., Walsh, N.: 1980, Ground displacements: local effects of the 1980 Irpinia earthquake 
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Maugeri, M., Motta, E., Sorriso Valvo, M.: 1982, The Senerchia landslide triggered by the 23 November 
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Nardi, R., Pochini, A., Puccinelli, A.: 1985, Contributo all’ analisi del territorio interessato dal sisma 
del 23 Novembre 1980: 1 – Cartografia geologica e geomorfologica di dettaglio dei centri abitati di 
Balvano, Muro Lucano e S. Gregorio Magno. 2 – Aree ad elavata franosità potenziale del territorio 
del comune di Balvano, Geologia Applicata e Idrogeologia XX, parte II, 591–593. 

Ortolani, F.: 1981, Principali effetti geologici di superficie del terremoto del 23-11-1980, Rendiconti 
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Ortolani, F., Pagliuca, S., Toccaceli, R.: 1990, Pericolosità geologica delle aree interessate dal terremoto 
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Ortolani, F., Torre, M.: 1981, Guida all’escursione nell’area interessata dal terremoto del 23-11-1980, 
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Pagliuca, S., Toccaceli, R. M.: 1992, Carta geomorfologica della comunità montana “Fortore 
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Rolandi, G.: 1986, Carta delle frane del Comune di Bella, Carta inedita allegata al Piano Regolatore 
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Samuelli-Ferretti, A., Siro, L.: 1983, Comune di Calitri (AV). Indagini di microzonazione sismica. 
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Samuelli-Ferretti, A., Vignola, N.: 1983, Comune di Torella dei Lombardi (AV) – microzonazione 
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S. PORFIDO ET AL. 
SUMMARY OF CONTRIBUTIONS ON 26 JULY 1805 EARTHQUAKE-INDUCED 
LANDSLIDES 

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Archivio di Stato di Napoli, Archivio Borbone, 690. 
Archivio di Stato di Napoli, Ministero delle Finanze, fascicoli 2478 e 2479. 
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