To define more accurately the near field and the directivity effect, different methodologies of
finite-fault modelling have been used to describe the behaviour of ground shaking based on
deterministic, stochastic and hybrid stochastic-deterministic approaches as in the framework of
the ongoing European project “LESSLOSS – Risk Mitigation for Earthquakes and
Landslides”.
In this study, we simulate and compare seismic scenarios obtained from the complex source
characteristic of the 1980 Irpinia earthquake, M 6.9, Southern Italy, using models based on
the source models hypothesized in Bernard and Zollo (1989) and in Valensise et al. (1990).
Furthermore, two finite-fault numerical approaches are used:
1. The approach RSSIM [Carvalho et al., 2004] that is a non-stationary stochastic simulation
method that synthesizes the ground motion due to an extended source;
2. The approach EXSIM [Motazedian and Atkinson, 2005] that is a new version of FINSIM
[Beresnev and Atkinson, 1998] introducing a new variation based on a “dynamic corner
frequency”.
The shaking scenarios are computed in terms of Response Acceleration Spectra (PSA), time
series, peak ground acceleration (PGA) at bedrock level. Source and path propagation
parameters taken from other studies were tested and the computed shaking scenarios are
compared to acceleration records to eight different stations. Preliminary results are here
presented in terms of PGA maps for the Campania region (Southern Italy)

Carvalho, A.

Zonno, G.

Earth-prints Repository

MODELING THE 1980 IRPINIA EARTHQUAKE BY STOCHASTIC SIMULATION.  
COMPARISON OF SEISMIC SCENARIOS USING FINITE-FAULT APPROACHES
G. ZONNO1 and  A. CARVALHO2 
1 INGV - Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Milano, Italy
2 LNEC - Laboratório Nacional de Engenharia Civil, Lisbon, Portugal
Paper No  1694
INGV LNEC
S U M M A R Y
To define more accurately the near field and the directivity effect, different methodologies of 
finite-fault modelling have been used to describe the behaviour of ground shaking based on 
deterministic, stochastic and hybrid stochastic-deterministic approaches as in the framework of 
the ongoing European project “LESSLOSS – Risk Mitigation for Earthquakes and 
Landslides”. 
In this study, we simulate and compare seismic scenarios obtained from the complex source 
characteristic of the 1980 Irpinia earthquake, M 6.9, Southern Italy, using models based on 
the source models hypothesized in Bernard and Zollo (1989) and in Valensise et al. (1990).  
Furthermore, two finite-fault numerical approaches are used: 
1. The approach RSSIM [Carvalho et al., 2004] that is a non-stationary stochastic simulation
method that synthesizes the ground motion due to an extended source;
2. The approach EXSIM [Motazedian and Atkinson, 2005] that is a new version of FINSIM 
[Beresnev and Atkinson, 1998] introducing a new variation based on a “dynamic corner 
frequency”.
The shaking scenarios are computed in terms of Response Acceleration Spectra (PSA), time 
series, peak ground acceleration (PGA) at bedrock level. Source and path propagation 
parameters taken from other studies were tested and the computed shaking scenarios are 
compared to acceleration records to eight different stations. Preliminary results are here 
presented in terms of PGA maps for the Campania region (Southern Italy).
ACKNOWLEDGEMENTS
This study was partially funded by the European 
Commission through the LESSLOSS FP6 Integrated Project 
Risk Mitigation for Earthquakes and Landslides, No.: GOCE-
CT-2003-505488 and partially by the Italian Dipartimento 
della Protezione Civile in the frame of the 2004-2006 
Agreement with Istituto Nazionale di Geofisica e 
Vulcanologia – INGV. The authors thank the following 
colleagues: R. Berardi (SOGIN SpA) for furnishing the ENEL 
- ENEA Irpinia Accelerometric Data Base; R. Basili (INGV) 
for the presentation of DISS 3.0.2 and for helpful discussion 
on the faults geometry of the 1980 Irpinia Earthquake and 
F. Meroni (INGV) for generating the figures of shaking maps 
using the GIS.
PRESENTION of the DATA BASE DISS 3.0.2  
Database of Individual Seismogenic Sources, (version 3.0.2)
Figure 1. DISS 3 is available through the internet at the URL:   
http://www.ingv.it/DISS/. The database can be navigated through a user-friendly 
cartographic interface. Data tables forming DISS are also available for download in 
several GIS formats.
The main object of the database is the seismogenic source, 
intended as a simplified and georeferenced 3D representation of a 
fault plane. Two categories of seismogenic sources based on 
geological/geophysical data are stored in the database: individual 
seismogenic sources and seismogenic areas. The database stores 
only seismogenic sources that are capable of earthquakes of M ≥ 5.5.
The individual seismogenic source is identified through geological and 
geophysical investigations, is capable of primary slip during a large 
earthquake and is assumed to exhibit “characteristic” behavior with 
respect to rupture length/width and expected magnitude. Each record 
of this category includes data on surface ruptures – when present and 
an evaluation of the uncertainties associated with the source. All 
records are fully parameterized and, thus, are ready to use in 
computer applications. (Yellow rectangles).
Seismogenic areas are crustal bodies for which a geographic outline, 
predominant faulting mechanism, effective depth, and expected 
maximum magnitude are supplied. Seismogenic areas are drawn with 
consideration of known large-scale tectonic structures, major 
earthquakes not associated with obvious tectonic structures, 
seismicity patterns, and long- and short-term strain observations. 
(Orange ribbons).
Unlike its predecessors, both the structure and the content of 
DISS 3 put significant emphasis on potential applications in 
the assessment of seismic hazard.
DISS Working Group (2005). Database of Individual Seismogenic Sources (DISS), Version 3.0.2: A compilation of potential sources for earthquakes larger than M 5.5 in Italy and 
surrounding areas. http://www.ingv.it/DISS/, © INGV 2005 - Istituto Nazionale di Geofisica e Vulcanologia - All rights reserved.
Amoruso A., Crescentini L. and R. Scarpa (2005) “Faulting geometry for the complex 1980 Campania-Lucania earthquake from levelling data”, Geophys. J. Int. (2005) 162, 156–168 
doi: 10.1111/j.1365-246X.2005.02652.
Berardi R., BERENZI A. and CAPOZZA F. (1981) “Campania-Lucania earthquake on 23 November 1980: accelerometric recordings of the main quake and relating processes, in 
Proceedings of the Progetto Finalizzato geodinamica Meeting on 'Sismicita deil'ltalia: stato delle conoscenze scientifiche e qualita delta normativa sismica', Udine, May 1981, pp.1-103.
Bernard P. and Zollo A. (1989) “The Irpinia (Italy) 1980 earthquake: detailed analysis of a complex normal faulting”, J. Geophys. Res., 94, 1631-1647.
Boschi E., Pantosti D., Slejko D., Stucchi M. and Valensise G. (Eds) (1993) - Special issue on the meeting “IRPINIA 10 ANNI DOPO”, Annals of Geophysics, Vol XXXVI, n. 1, April 1993.
Boore, D.M. (2003). “Simulation of ground motion using the stochastic method,” Pure Appl. Geophys. 160, pp. 635-676. 
Carvalho, A.; Campos Costa, A.; Sousa Oliveira, C. [2004]. “A stochastic finite-fault modeling for the 1755 Lisbon earthquake,” 13th World Conference on Earthquake Engineering 
Vancouver, B.C., Canada August 1-6, 2004 Paper No. 2194
Carvalho, A.; Zonno, G.; Franceschina, G.; Bilé Serra J. and Campos Costa, A. [2006]. “Earthquake shaking scenarios for the Metropolitan Area of Lisbon”, submitted to Soil Dynamics 
and Earthquake Engineering.
DISS Working Group (2005). Database of Individual Seismogenic Sources (DISS), Version 3.0.2: A compilation of potential sources for earthquakes larger than M 5.5 in Italy and 
surrounding areas. http://www.ingv.it/DISS/, © INGV 2005 - Istituto Nazionale di Geofisica e Vulcanologia - All rights reserved. 
Main references
Ferrer, I., Sanchez-Carratala, C. R. [2004]. “Application of non-stationary seismological models to the determination of stochastic response spectra,” 13th World 
Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004 Paper No. 2280
Faravelli, L. [1987]. “Modelling the seismic input for a stochastic dynamic structural problem”. 5th International Conference on Application of Statistics and 
Probability in Soil and Structures, Vancouver, 230 – 237.
Pantosti D. and Valensise G. (1990) “Faulting mechanism and complexity of the 23 November, 1980 Campania-Lucania earthquake inferred from surface 
observations”, J. Geophys. Res., 95, 15319-15341.
Valensise G., Amato A., Beranzoli L., Boschi E., Cocco M., Giardini D. and Pantosti D. (1989) “Un modello di sintesi del terremoto Campano-Lucano del 23 Novembre
1980”, Atti 8 Convegno G.N.G.T.S., Roma 1989.
Westaway R. and Jackson R. (1987) “The earthquake of 1980 November 23 in Campania-Basilicata (Southern Italy)”, Geophys. J. R. astr. Soc, 90, 375-443.
Motazedian D. and Atkinson G.M. (2005) “stochastic Finite-Fault Modeling Based on Dynamic Corner Frequency”, BSSA, Vol. 95, n.3, pp995-1010, June 2005. 
Doi:10.1785/0120030207.
Beresnev, I.A., Atkinson, G.M. [1998]. “FINSIM - a FORTRAN program for simulating stochastic acceleration time histories from finite fault,” Seism. Res. Lett., 69, 
pp. 27-52.
Sousa, M.L., Campos Costa A., Carvalho, A., Coelho, E. [2004] “An automatic seismic scenario loss methodology integrated on a geographic information system,” 
13th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004 Paper No. 2526
Figure 6. – Left: geometry of the faults of the Irpinia region from DISS 3.0.2; Right: a spot of DISS 3.0.2 on the  
geometry of the faults (yellow lines) of the 1980 Irpinia Earthquake (after named as MODEL B) and the 
locations (blue triangles) of the accelerometric stations used in this study. 
A reference PGA map coming from 3D Finite-Fault geometry of Individual Seismogenic
Sources of the Italy, represented in the data base DISS 3.0.2, could give important 
constrains and improvements in the assessment of local seismic hazard. The total 
contribution of the seismic scenarios (an example is given in the following in terms of PGA 
parameter) could give a general reference (at the bedrock) for the ground motion shaking 
overcoming the paucity of available accelerometric records.
A stochastic reference PGA map using the Data Base DISS 3.0.2
Figure 3. The figure shows the fault geometry of the Model A and 
Model B that are coming respectively from a modification of the 
original model of Bernard and Zollo (1989) and from the model of 
Valensise et al. (1990) as it is stored in the Data Base DISS 3.0.2.  
The solid red traces represent the outcrop lines close to the most 
superficial edge of the faults while the pink circles are the origins of 
three faults following the convention defining strike direction is that 
fault always dips to the right of it (used in the EXSIM program).
MAIN OUTCOMES
In this study we have obtained some preliminary results in:
• producing a reference PGA map coming directly from DISS 3.0.2;
• comparing two fault models (Model A and Model B) of the 1980 
Irpinia earthquake in terms of simulated time series;
• comparing the capacity of two finite-fault methods (RSSIM and 
EXSIM) in terms of simulated 5 % damped response spectra;
• trying to study some of the features of the complex source 
characteristic of the 1980 Irpinia earthquake, Southern Italy, using 
simple kinematic source models.
Figure 7. Left: Simulated time series 
at the 8 stations (see Figure 3 and 
Table 2). The contribution of the three 
faults, named 0 sec, 20 sec and 40 
sec) are obtained adding in the time 
domain the simulated 3 time series 
with a delay of 20 and 40 sec. 
Right Top: comparison of the 
components NS, DU and WE at the 
station BRN with the EXSIM simulated 
time series (green line) using the 
Model B. 
B B  
R R  
I I I 
E E  
NN
Z Z  
AA
Figure 11. Campania probabilistic PGA map from “Gruppo di Lavoro MPS 
(2004). Redazione della mappa di pericolosità sismica prevista dall'Ordinanza
PCM 3274 del 20 marzo 2003. Rapporto Conclusivo per il Dipartimento della 
Protezione Civile, INGV, Milano-Roma, aprile 2004, 65 pp. + 5 appendici”
Figure 10. This map presents Campania region and also Basilicata region where it is located 
20s fault. The stochastic PGA map is obtained from RSSIM using the 1980 Irpinia Earthquake 
fault model MODEL A (modified Bernard & Zollo, 1989). The computation has been done at 
level of municipalities.
Figure 13. Campania stochastic PGA map (for a grid of 0.02 x 0.02 
degree) from EXSIM using the 1980 Irpinia Earthquake fault model 
MODEL B [DISS 3.0.2, DISS Working Group (2005)]. Warning: 
the results are preliminary because we have used only 3 trials.
Figure 8. Comparison of computed response spectra 
from records of Irpinia data set (ENEL – ENEA) and the 
EXSIM simulated response spectra (red line), using the 
Model B.
Figure 5. Comparison of the 5% damped response spectra (components:  WE (green line) and NS (blue line)) 
from the observed data [correction ORMSBY filter in the time domain: .50 - .70 and 25. – 27. Hz] with the 
simulated response spectra using the Model A.  Left: results from the method RSSIM using different options (see 
Note 1); Right: results from the method EXSIM [5% damping and SARAGONI-Hart window 0.1 – 40. Hz]. 
Figure 12. Campania stochastic PGA map (for a grid of 0.02 x 0.02 
degree) from EXSIM using the 1980 Irpinia Earthquake fault model 
MODEL A (modified from Bernard & Zollo, 1989). Warning: the 
results are preliminary because we have used only 3 trials.
The EXSIM program (Extended Finite-
Fault Simulation, Motazedian and 
Atkinson, 2005) is an updated version of 
FINSIM. The modifications to FINSIM 
introduce the new concept of a “Dynamic 
corner frequency”. The model has several 
significant advantages over previous 
stochastic finite-fault models, including 
independence of results from sub_fault 
size, conservation of radiated energy, 
and the ability to have only a portion of 
the fault active at any time during the 
rupture (simulating self-healing 
behaviour (Heaton,1990)).
NOTE 1. Legend of Figure 5 Left. The colors mean: YELLOW - original scaling factor, all station 
with f1 filter; GREEN - original scaling factor, f1 filter only distances > 30 km; BLUE - original 
scaling factor, without filter and RED - Boore scaling factor, all f1 filter.
The 1980 Irpinia Earthquake
On 23 November 1980 a violent earthquake hits the Campania and Basilicata regions, causing nearly 3,000 deaths and 
severely damaging homes and infrastructures. The 1980 Irpinia Earthquake is a complex event that involves at least 
three distinct ruptures in a time span of approximately 40 sec. The main event (0s) was followed by a rupture episode 
about 20s after and one 40s after the starting of the earthquake. Different analogic accelerograms were recorded during 
the events but only 8 of them were within 50km from the hypocenter. This earthquake was widely studied and a 
complete review was published in the proceedings of the Special issue on the meeting “IRPINIA 10 ANNI DOPO” (Annals 
of Geophysics, Vol. XXXVI, n. 1, April 1993). Other main references are indicated in the bottom box.
Stochastic shaking simulations
As first we did stochastic shaking simulations of the Finite-Fault approaches RSSIM
and EXSIM comparating the observed 5% damped response spectra with the 
simulated response spectra (Figure 5 and Figure 8). The main input parameters of this 
stochastic simulations are the fault geometry, the location of the nucleation point, the 
average elastic properties of the propagation media, such as crustal shear velocity, 
density and attenuation factors, and source related parameters as seismic moment 
and slip distribution on the fault.  We don’t use the random slip distribution because 
it gave a vorser fit between the computed and simulated response spectra. We 
assumed that both Model A and Model B have a regular geometric distribution in the 
slip distribution (see Figure 2 and Figure 9). The position ( , ) of the sub-fault of the 
nucleation points are shown in the Table 1. For the Model A we used the location of 
nucleation points (from literature) that takes better results but for the Model B we 
assumed a bilateral rupture that means a nucleation point in the centre of the fault. 
Using EXSIM (we have changed EXSIM code so to perform multiple ruptures) we 
have adopted the option of dynamic corner frequency model (with the value of 50% of 
the fault actively slipping at any time in the rupture) with a stress drop of 100 bars, 
a value of Q equal to 100 and a value of k of 0.03. We have used the given slip 
distributions shown in the Figures 2 and 9. On the subdivision of fault we keep values 
to have the grid size of about 2 km x 2 km for all three faults (0 s, 20 s and 40 s).
Using RSSIM the same  stress drop, Q  and k values were adopted as well as the 
same slip distribution and fault parameters. In this method, a impedance function, f1, 
is used to take into account the impedance effect caused by the change in the density 
and S-wave propagation velocity from the source region to the prediction site [see 
Ferrer and Sánchez-Carratalá, 2004]. It was adopted the expression 
f1(f)=2/[1+(fzi/f)2] for f>fzi, with fzi=0.32 Hz according to Faravelli [1987]. 
The comparison of PGA maps
Figure 2.
The total 
amount of 
slip 
distribution 
is given 
from the 
assigned 
value of Mw 
(Table 1) 
and is 
concentrate, 
for each 
fault, 
following a 
simple 
schematic 
geometry.
B B  
R R  
I I I 
E E  
NN
Z Z  
AA
Figure 4. Left: comparison of 
the accelerometric components 
NS, DU and WE at the station 
Bagnoli Irpino (BGI), Calitri
(CLT) and Brienza (BRN) with 
the respectively simulated time 
series (green line) using the 
program EXSIM and the Model 
A. At the station of Brienza the 
Model gives a simulated time 
series more comparable with the 
observed one. 
Comment on the used methods
The RSSIM method, coming from FINSIM, 
is customized for engineering applications 
and is devoted to take into account the soil 
effects in a very efficient way.
It has a disadvantage when working in the 
frequency domain with a non-stationary 
stochastic approach, as it loses the capacity 
to produce time series at the analyzed 
sites. For this reason both the methods are 
to be used following the necessity of the 
specific applications. Of course, all the new 
features like those of the EXSIM program 
will be updated in the RSSIM method too.
The sub-event (20 s)
While the main features of the first (0 s) 
and of the last (40 s) sub-events are widely 
accepted, the second sub-event (20 s) is 
still controversial and very different models 
have been assumed in the available 
literature. 
The research of some elements to 
support a model against the other ones 
is out the scope of this study. 
To perform this study we have assumed 
basically only the models of Bernard and 
Zollo (1989) and in Valensise et al. (1990) 
as shown in Figure 3 and with the 
parameters represented in Table 1.
Stochastic reference PGA maps Stochastic reference P A aps i  f    
using the Data Base DISS 3.0.2using the ata Base ISS 3.0.2i      . .
http://zonesismiche.mi.ingv.it/mappa
_ps_apr04/griglia002/campania.html
Model A : 
used slip distributions 
Model B : 
used slip distributions 
Figure 9. The total amount of slip 
distribution is given from the assigned 
value of Mw (Table 1) and is 
concentrated, for each fault, following a 
regular simple schematic geometry 
around the nucleation point. In the 
Model B the nucleation points are 
always located in the centre of faults 
(see Table 1). The dip angle of the fault 
is not shown in this projection, the 
same appears for the Figure 2.
Table 1.  Parameter 
of the fault models 
used in this study 
(Model A and Model 
B; see the Figure 3). 
In the table are 
indicated the position 
of the nucleation 
points in respect to 
the number of the 
sub_faults.
Table 2. Name references (ENEL-ENEA) of 
the used records at the stations: Bagnoli 
Irpino, Sturno, Rionero in Vulture, Auletta, 
Mercato San Severino, Calitri, Bisaccia and 
Brienza (see also the Figure 3). 
Short description on the used simulation methods
The RSSIM (Carvalho et al., 2004) approach is a non-stationary stochastic 
simulation method that synthesizes the ground motion due to an extended source. 
This method has been implemented starting from the classic simulation code 
FINSIM (Beresnev and Atkinson, 1998).  
Like FINSIM, the RSSIM method assumes that the fault plane is a rectangle, 
subdivided into an appropriate number of sub-faults, which are modelled as point 
sources characterized by an ω2 spectrum. 
Differently from FINSIM, RSSIM avoids the computation of acceleration time series 
representing the contribution of each sub-fault, but synthesizes the ground motion 
due to the entire fault from the Power Spectral Density Function (PSDF) radiated by 
each sub-fault, using the random vibration theory and the extreme values statistics. 
The RSSIM program is a part of LNECloss system (Sousa et al., 2004)


Modeling the 1980 Irpinia earthquake by stochastic simulation. Comparison of seismic scenarios using finite-fault approaches

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Modeling the 1980 Irpinia earthquake by stochastic simulation. Comparison of seismic scenarios using finite-fault approaches

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