INGVPublished1.1. TTC - Monitoraggio sismico del territorio nazionaleope

Ameri, G.

Augliera, P.

Bindi, D.

D'Alema, E.

Ladina, C.

Lovati, S.

Luzi, L.

Marzorati, S.

Massa, M.

Pacor, F.

Puglia, R.

English

Earth-prints

Open File Report: 
http://www.mi.ingv.it/docs/report_RAN_20090406.pdf 
2009
Strong­motion parameters of the Mw=6.3 
Abruzzo (Central Italy) earthquake
Ameri G., Augliera P., Bindi D., D'Alema E., Ladina C., Lovati S., 
Luzi L., Marzorati S., Massa M., Pacor F. and Puglia R. 
Strong-motion parameters of the Mw=6.3 Abruzzo (Central Italy) earthquake 
 
Ameri G., Augliera P., Bindi D., D’Alema E., Ladina C., Lovati S., Luzi L., Marzorati S., 
Massa M., Pacor F. and Puglia R.  
 
INGV sezione di Milano-Pavia, Italy  
 
UPDATED 21 May 2009: EC8 site classification of AQG and AQK stations have 
been revised by S4-project team (http://esse4.mi.ingv.it); Table 2 has been modified 
accordingly.  
 
1. Introduction 
 
On April 6, 2009 at 01:32:39 GMT a magnitude Mw=6.3 (Harvard CMT) earthquake 
occurred in the Abruzzo region (Central Italy), close to the town of L’Aquila (located at 
about 6 km northeast to the epicenter). The mainshock has been recorded by 55 stations 
belonging to the Italian Strong Motion Network (RAN managed by the Italian 
Department of Civil Protection, DPC) 
(http://www.protezionecivile.it/minisite/index.php?dir_pk=1036&cms_pk=15425). Soon 
after the earthquake occurred the first emergency structures of the National Earthquake 
Centre of INGV (Struttura di Pronto Intervento, SPI) was activated, to install in the 
epicentral area the stations of the real-time temporary seismic network. In addition 
several institutions, such as the Istituto Nazionale di Geofisica e Vulcanologia (INGV), 
the University of Potenza and the Helmholtz-Zentrum Potsdam (Deutsches 
GeoForschungsZentrum – GFZ) installed about 30 stations to detect site effects and the 
response of buildings. In Figure 1 the RAN stations installed in the epicentral area are 
shown. This event is the third largest earthquake recorded by strong-motion instruments 
since 1972, after the 1976 Friuli (Mw=6.4) and the 1980 Irpinia (Mw=6.9).  
In this note we present the strong motion parameters of engineering interest computed for 
the mainshock, recorded by the stations of the RAN. 
 
Figure 1- Distribution of the RAN seismic stations installed in the epicentral area. The epicenter is shown 
as a red star.   
 1
2. Events and historical seismicity 
 
The April 6, 2009 Abruzzo earthquake has been generated by a normal fault, with NW-
SE trend and SW dip. The strongest aftershocks occurred on April 7 at 17:47:37 (Mw = 
5.5), located south-east to the mainshock (Figure 2), and on April 9 at 00:52:59 (Mw = 
5.4) in the Monti della Laga area, located north to the mainshock. The hypocentral 
coordinates and the main parameters of the strongest events are shown in Table 1, where 
the focal solution is shown as well.  
 
Table 1- Main events of the sequence  
ID Date OT Lat(1) Lon(1) depth(1) Ml(1) Mw* strike;dip;rake* 
2206550980 09/04/2009 19:38:16 42.501 13.356 17.2 4.9 5.2 123, 53, -110 
2206541910 09/04/2009 04:32:44 42.445 13.42 8.1 4   
2206539720 09/04/2009 00:52:59 42.484 13.343 15.4 5.1 5.4  130, 48, -112 
1206521070 07/04/2009 17:47:37 42.275 13.464 15.1 5.3 5.5 106, 51, -138 
2206516040 07/04/2009 09:26:28 42.342 13.388 10.2 4.7   
2206509940 06/04/2009 23:15:37 42.451 13.364 8.6 4.8   
2206505980 06/04/2009 16:38:09 42.362 13.333 10.2 4   
2206497570 06/04/2009 02:37:04 42.366 13.34 10.1 4.6   
2206496920 06/04/2009 01:32:39 42.334 13.334 8.8 5.8 6.3 127, 50, -109 
(1) Istituto Nazionale di Geofisica e Vulcanologia 
*Harvard CMT 
 
 
Figure 2- Mainshock and aftershocks of the L’Aquila sequence. 
 
 2
This area has been struck by destructive earthquakes in the past documented since 1300 
BC (Stucchi et al., 2007). The three strongest earthquakes occurred in 1349 (epicentral 
intensity I0=IX-X MCS), 1461(I0=X) and 1703 (I0=X). The historical seismicity of 
L’Aquila is shown in Figure 3. In particular, the 26 November 1461 event presents an 
epicenter location and a distribution of the most damaged sites (Figure 4) comparable to 
the observed damage after the L’Aquila mainshock. 
 
 
 
Figure3- Historical seismicity of L’Aquila. (Stucchi et al., 2007) 
 
 
 
 
Figure 4 - 1461 earthquake intensity data (Stucchi et al., 2007) 
 
 
 3
3. Recording stations 
 
The mainshock has been recorded by 55 stations of the Italian strong motion network 
(RAN). 
Table 2 lists the main characteristics of the recording stations. Two site classifications are 
proposed. The first is the one adopted by Sabetta and Pugliese (1987, 1996) where 3 
classes are discriminated on the base of shear wave velocity and depth (0 = rock sites, 1 = 
deposits with depth less than 20 m; 2 = deposits with depth larger than 20m) and the 
second is the EC8 classification derived from geological/geophysical information (project 
S4, http://esse4.mi.ingv.it). In particular, the classes denoted with star have been 
attributed on the basis of a direct measure of the Vs30. Most of the stations belong to 
class A or B, while few stations belong to class C.  
 
Table 2 - RAN Stations  
Code Name lat Lon class_SP class_EC8 
ANT  ANTRODOCO  42.418 13.079 0 A 
AQA  L'AQUILA - V. ATERNO -F. ATERNO  42.376 13.339 1 B 
AQG  L'AQUILA - V. ATERNO -COLLE GRILLI  42.373 13.337 1 A 
AQK  AQUIL PARK ING.  42.345 13.401 2 B 
AQV  L'AQUILA - V. ATERNO - CENTRO VALLE  42.377 13.344 2* B* 
ASS  ASSISI  43.075 12.604 0 A 
AVL AVELLINO 40.923 14.787 1 B 
AVZ  AVEZZANO  42.027 13.426 2 C 
BBN BIBBIENA 43.748 11.821 2 C 
BDT BADIA TEDALDA 43.707 12.188 0 A 
BNE BENEVENTO 41.128 14.785 1 B 
BOJ  BOJANO  41.484 14.472 2 C 
CDS  CASTEL DI SANGRO  41.787 14.112 0 A 
CER CERIGNOLA 41.26 15.91   
CHT  CHIETI  42.37 14.148 2 C 
CLN  CELANO  42.085 13.521 0 A 
CMB CAMPOBASSO 41.563 14.652 0 A 
CMR CASTELMAURO 41.833 14.712   
CNM CASALNUOVO MONTEROTARO 41.618 15.105 0 A 
CSO1  CARSOLI 1  42.101 13.088 0 A 
CSS  CASSINO  41.486 13.823 0 A 
CTL CATTOLICA 43.955 12.736   
FMG  FIAMIGNANO  42.268 13.117 0 A 
FOR FORLI' 44.199 12.042 2 C 
GNL GENZANO DI LUCANIA 40.843 16.033 0 A 
GSA  GRAN SASSO (ASSERGI)  42.421 13.519 0 A 
GSG  GRAN SASSO (LAB. INFN GALLERIA)  42.46 13.55 0 A 
ISR  ISERNIA  41.611 14.236 1 B 
LSS  LEONESSA  42.558 12.969 0 A 
MMP1  MOMPEO 1  42.249 12.748 0 A 
MNG MONTE S. ANGELO 41.704 15.958   
MNN MANFREDONIA 41.634 15.911 0 A 
MTR  MONTEREALE  42.524 13.245 2 A 
NAP NAPOLI OVEST 40.799 14.18 2 C 
ORC  ORTUCCHIO  41.954 13.642 0 A 
PDM PIEDIMONTE MATESE 41.355 14.385 2 C 
 4
Code Name lat Lon class_SP class_EC8 
PIC PIANCASTAGNAIO 42.85 11.685 1 B 
PTF  PETRELLA TIFERNINA  41.696 14.702   
RIC RICCIA 41.483 14.838 0 A 
SBC  SUBIACO  41.913 13.106 0 A 
SCM S. CROCE DI MAGLIANO 41.711 14.984 1 B 
SCP  SERRACAPRIOLA  41.807 15.165   
SDG S. GIOVANNI ROTONDO 41.709 15.733   
SEP S. ELIA A PIANISI 41.625 14.88 0 A 
SNM SAN MARINO 43.934 12.449 0 A 
SNS SANZA 40.243 15.55 0 A 
SPC  SPOLETO (CANTINA)  42.743 12.74 2 C 
SPO  SPOLETO  42.734 12.741 0 A 
SSR  S. SEVERO  41.691 15.374 2 C 
STN STURNO 41.018 15.112 0 A 
SUL  SULMONA  42.089 13.934 0 A 
TLS TELESE TERME 41.222 14.53 0 A 
TMO  TERMOLI  41.989 14.975   
VIE VIESTE 41.877 16.165   
VRP VAIRANO PATENORA 41.333 14.132 1 B 
 
 5
4. The strong motion records of the mainshock 
 
The mainshock strong-motion data have been recorded at epicentral distances ranging 
from 4 to 297 km and Joyner-Boore distances (Rjb) ranging from 0 to 284 km (in the 
following we will assign, for graphic reasons, Rjb=1 to sites formally having Rjb=0). In 
particular, 23 records at distances smaller than 50 km are available. To compute the Rjb 
distance, the geometry of the fault has been hypothesized by merging different 
information, such as geology, distribution of the aftershocks and geodetic observations 
(Figure 5).  
 
Figure 5 - Fault geometry plotted against the main events. Triangles show the RAN seismic stations 
installed in the epicentral area. 
 
In Table 3 the main parameters for each strong motion record (epicentral and Joyner-
Boore distances, maximum horizontal PGA and maximum horizontal PGV) are listed.  
The observed largest PGA (PGV) is 646 cm/s2 (43 cm/s) recorded at station Valle 
dell’Aterno – Centro Valle (AQV), but, in general all the near fault PGA are larger than 
350 cm/s2 and the PGV are larger than 30 cm/s.  
Figure 6 shows the EW component of the acceleration time series recorded by the closest 
stations to the epicenter (AQK, AQA, AQV and AQG). Near-source long-period pulses, 
possibly related to source effects, are present in all the records. However the effect of the 
site response, discussed in paragraph 7, is visible in L’Aquila (AQK) record which shows 
the highest low frequency content and in the AQA record, which exhibits a high-
frequency content. 
 6
Table 3 - Peak ground acceleration and velocity recorded at each RAN station (maximum between the 
horizontal components) 
Code Rjb (km) Repi (km) Max H PGA 
(cm/s2) 
Max H PGV 
(cm/s) 
ANT 19.3 23.0 25.98 2.47 
AQA 0.1 4.6 435.63 32.03 
AQG 0.1 4.4 506.86 35.54 
AQK 0.1 5.6 347.23 36.21 
AQV 0.1 4.9 646.07 42.83 
ASS 96.5 101.7 6.04 0.43 
AVL 185.7 198.0 1.25 0.38 
AVZ 25.1 34.9 67.68 11.28 
BBN 194.5 199.5 1.00 0.24 
BDT 172.8 178.8 1.99 0.38 
BNE 167.9 180.2 2.06 0.68 
BOJ 121.1 133.4 14.16 3.33 
CAN 217.6 217.6 1.86 0.33 
CDS 76.2 88.4 9.95 1.72 
CHT 52.2 67.0 29.41 7.91 
CLN 20.0 31.6 89.14 6.64 
CMB 126.5 138.7 2.88 1.30 
CMR 112.9 126.6 5.34 0.74 
CNM 153.1 166.6 1.88 0.84 
CSO1 31.7 33.5 18.28 2.29 
CSS 91.1 102.6 9.44 1.64 
CTL 178.8 186.7 4.37 0.76 
FMG 16.6 19.3 26.34 2.61 
FOR 225.6 232.3 1.58 0.63 
GNL 266.5 279.0 2.19 0.57 
GSA 8.6 18.0 148.22 9.84 
GSG 13.7 22.6 29.43 3.04 
ISR 97.3 109.7 7.21 0.78 
LSS 35.6 39.0 9.64 0.83 
MMP1 45.9 49.1 8.83 0.89 
MNN 212.4 226.8 2.38 0.28 
MTR 15.9 22.4 61.58 3.53 
NAP 173.1 184.6 2.65 0.83 
ORC 37.3 49.3 64.23 5.86 
PDM 127.1 139.4 1.54 0.30 
PIC 143.0 146.7 1.24 0.30 
PTF 120.4 133.4 6.86 1.31 
RIC 144.1 156.3 2.54 0.56 
SBC 46.6 50.4 6.64 1.26 
SCM 139.2 152.9 4.32 0.80 
SCP 147.8 162.1 5.65 1.19 
SDG 195.6 191.6 1.33 0.20 
SEP 137.1 150.2 3.67 0.83 
SNM 184.7 191.9 2.29 0.70 
SNS 284.9 167.9 3.82 0.74 
SPC 63.2 66.7 7.55 0.69 
SPO 62.6 65.9 9.57 0.81 
SSR 169.0 183.1 5.33 1.25 
STL 277.0 277.0 0.94 0.27 
STN 195.6 207.8 1.32 0.29 
SUL 43.4 56.4 33.64 3.73 
TLS 146.2 158.5 2.59 0.56 
TMO 126.0 140.6 9.84 2.88 
VIE 224.2 239.0 2.21 0.48 
VRP 117.5 129.4 3.53 0.81 
 7
30 35 40 45 50 55
-500
0
500
Time [s]
P
G
A
 [g
al
]
2009/04/06 01:32:39 (Mw 6.3) EW component AQV
30 35 40 45 50 55
-500
0
500
Time [s]
P
G
A
 [g
al
]
2009/04/06 01:32:39 (Mw 6.3) EW component AQK
 
15 20 25 30 35 40
-500
0
500
Time [s]
P
G
A
 [g
al
]
2009/04/06 01:32:39 (Mw 6.3) EW component AQA
 
 
30 35 40 45 50 55
-500
0
500
Time [s]
P
G
A
 [g
al
]
2009/04/06 01:32:39 (Mw 6.3) EW component AQG
 
Figure 6 - EW component of the acceleration time series recorded by the stations located within 6 km from 
the epicenter.  
 
 
5. Comparison with predictive models 
 
Corrected data have been obtained by a standard processing (non standard errors 
removal, baseline correction, band pass filtering with acasual filter selected by visual 
inspection, integration of the corrected acceleration in order to obtain velocity). The peak 
ground motions calculated from processed data have been compared with the prediction 
obtained using different ground motion prediction equations (GMPEs): Sabetta and 
Pugliese (1996, SP96), Bindi et al. (2008, ITA08), Ambraseys et al. (2005, AM05), 
Faccioli and Cauzzi (2008, FC08) and Akkar and Bommer (2007, AkBo07). Note that 
ITA08 and SP96 GMPEs are calculated using data from Italian earthquakes only. In the 
 8
following (unless otherwise noted) we will plot the ground motion estimated from 
GMPEs in terms of mean ± one standard deviation. 
Figure 7 shows the comparison with ITA08 and SP96 both for the maximum horizontal 
and vertical components.  
In general, ITA08 underestimates the peak acceleration of sites located within the surface 
projection of the fault (Rjb = 0.0 km) by about a factor of 2, while Sabetta and Pugliese 
(1996) does not. Both overestimate the acceleration for distances larger than 20 km. A 
better fit is obtained for the peak ground velocity, especially for the vertical component.  
 
 
Figure 7 - Left: recorded PGAs for different site classes plotted as a function of the Rjb distance compared 
with the ITA08 and SP96 median ± one standard deviation curves for rock sites and for maximum 
horizontal component (Top) and vertical component (Bottom). Right: the same as left figures but for PGV. 
 
As a preliminary investigation of the possible causes of the peak parameters 
overestimation, the stations  (for Rjb < 100km) are subdivided by their azimuth from the 
epicentre in order to look for potential asymmetries in the ground motion distribution. In 
Figure 8 we compare ITA08 with observations divided into two azimuth classes. Red 
dots indicate stations having azimuth from 0° to 180° (located eastward to the epicenter), 
while blue dots span the remaining azimuths (sites located westward to the epicenter). It 
can be noticed how almost all the sites with azimuth from 180° to 360° are 
overestimated.  
 
 
 9
 
Figure 8- ITA08 curves for rock site compared with observed values divided into two azimuth classes. Red 
symbols indicate sites located at azimuths between 0 and 180°, blue symbols sites with azimuths between 
180° and 360° 
 
In Figure 9, the acceleration response spectra for horizontal (RSHA) and vertical (RSVA) 
components (at 5% damping), observed at two different stations (AQG – class B and 
GSA – Class A) are compared with the ITA08 predictions. A fairly good fit is observed 
at both stations although ITA08 underestimates the spectra recorded at AQG station at 
long periods. 
 
 
Figure 9 - Observed response spectra at two stations compared with ITA08 predictions.  
 
 
 10
Figures 10 and 11 show the comparisons with other ground motion prediction equations 
based on European (Ambraseys, 2005; Akkar and Bommer, 2007) and worldwide 
(Cauzzi and Faccioli, 2008) strong motion records. In general, all the predictive models 
overestimate the PGA recorded at distances larger than 30 km, while a better fit is found 
for PGV. 
 
 
 
Figure 10 - Comparison between observed data and AM05 predictions (rock sites) for Horizontal (left) and 
vertical (right) maximum horizontal PGA. ITA08 curves  are also shown. 
 
Figure 11 - Comparison between observed data and CF08 predictions (rock sites, Vs30=1000m/s) for 
hypocentral distance and for geometric mean of horizontal PGAs.  
 
 11
 
Figure 12 -  comparison between observed data and the AkBo07 predictions (rock sites) for maximum 
horizontal PGV. ITA08 curves are also shown.  
 
6. Comparison with EC8 
 
In Figure 13 the 5% damped acceleration response spectra for two near-fault records 
belonging to soil class A and B are compared with the EC8 spectral shapes and the 
ITA08 GMPE. The EC8 spectrum is scaled with the expected peak ground acceleration 
with 10% probability of exceedance in 50 years. The spectrum designed for rock sites is 
conservative at high periods, while the observations for class B exceed both short periods 
(0-0.4s) and intermediate periods (0.8 – 1.5s).  
 
 12
 
    
Figure 13 - Comparison between observed spectra and EC8 spectral shapes scaled to the PGA of the 
national hazard map (0.25 g).  
 
 
7. Site effects in the upper Aterno valley 
 
A strong motion array, transversal to the upper Aterno valley composed of 7 stations, has 
been installed by the Italian civil protection, in order to detect the variation of the seismic 
motion along the valley (Figure 14). For some stations of the array we performed H/V 
ratio in order to detect the resonance frequency, using the ground motion recorded by the 
national accelerometric network before 2005. In particular, the site Valle dell’Aterno 
centro valle (AQV), was investigated in detail in the project “Italian strong motion data 
base in the period 1972-2004 in the framework of the agreement between Istituto 
Nazionale di Geofisica e Vulcanologia and Department of Civil Protection 2004-2006. A 
cross-hole test is available for the site shown in Figure 15.  
 13
The station Aquilpark (AQK), installed in the L’Aquila town has a remarkable 
amplification at low frequency (about 0.6 Hz, figure 16c), as also demonstrated by De 
Luca et al. (2005) using weak motion and ambient noise data. The stations AQV, AQA 
and AQG installed in the upper Aterno valley have a response at higher frequencies than 
AQK (2 Hz, 9.5 Hz and a broad amplification range between 2 and 6 Hz, respectively), as 
shown in  Figure 16a-b-d. In Figure 16d is also shown the 1D linear model computed 
from the shear wave velocity profile in Figure 15. 
 
 
 
 
Figure 14 - geologic map of the upper Aterno valley. Squares indicate the array stations. 
 14
 0
10
20
30
40
50
60
0 500 1000 1500
V (m/s)
D
ep
th
 (m
)
Vs
 
Figure 15 - shear wave velocity profile at AQV (ITACA database http://itaca.mi.ingv.it) 
0
2
4
6
8
10
12
14
16
18
20
0.1 1.0 10.0 100.0
Frequency (Hz)
A
m
pl
itu
de
mean + 1 std
mean 
mean - 1 std
0
2
4
6
8
10
12
14
16
18
20
0.1 1.0 10.0 100.0
Frequency (Hz)
A
m
pl
itu
de
mean + 1 std
mean
mean - 1 std
 
   (a)      (b) 
0
2
4
6
8
10
12
14
16
18
20
0.1 1.0 10.0 100.0
Frequency (Hz)
A
m
pl
itu
de
mean + 1 std
mean
mean - 1 std
0
2
4
6
8
10
12
14
16
18
20
0.1 1 10 100
Frequency (Hz)
A
m
pl
itu
de
1D
mean - 1 std
mean 
mean + 1 std
 
   (c)      (d) 
Figure 16 - H/V spectral ratios from strong motion data at a) AQA, b) AQG, c) AQK, d) AQV  
 
 
 
 
 15
 
Acknowledgements 
 
In this report we made use of the records available thanks to the work carried out by 
Monitoraggio del Territorio e gestione banche dati of the Dipartimento della Protezione 
Civile - Ufficio Valutazione, Prevenzione e Mitigazione del Rischio Sismico (SISM). 
 
 
 
References 
 
Akkar S, Bommer JJ (2007) Empirical Prediction Equations for Peak Ground Velocity 
Derived from Strong-Motion Records from Europe and the Middle East. Bull Seism Soc 
Am., 97, 511-530. 
 
Ambraseys, N. N., Douglas, J., Sarma, S. K. and P. M. Smit (2005). Equations for the 
estimation of strong ground motions from shallow crustal earthquakes using data from 
Europe and Middle East: Horizontal peak ground acceleration and spectral acceleration. 
Bull. Earth. Eng., 3, 1-53. 
 
Cauzzi C. and E. Faccioli (2008) Broadband (0.05 to 20 s) prediction of displacement 
response spectra based on worldwide digital records. J. Seismol., 12, 453-475 
 
Bindi D., L. Luzi, M. Massa, F. Pacor (2008) Horizontal and vertical ground motion 
prediction equations derived from the Italian Accelerometric Archive (ITACA). Bull 
Earth. Eng., submitted. 
 
G. De Luca, S. Marcucci, G. Milana, T. Sano' (2005) - Evidence of Low-Frequency 
Amplification in the City of L'Aquila, Central Italy, through a Multidisciplinary 
Approach Including Strong- and Weak-Motion Data, Ambient Noise, and Numerical 
Modeling. Bull Seism Soc Am., 95, 1469 - 1481. 
 
Sabetta F, Pugliese A (1987) Attenuation of peak ground acceleration and velocity from 
Italian strong motion records. Bull Seism Soc Am., 77, 1491-1513. 
 
Sabetta F, Pugliese A (1996) Estimation of response spectra and simulation of non-
stationary earthquake ground motions. Bull Seism Soc Am., 86, 337-352. 
 
Stucchi et alii. (2007). DBMI04, il database delle osservazioni macrosismiche dei 
terremoti italiani utilizzate per la compilazione del catalogo parametrico CPTI04. 
http://emidius.mi.ingv.it/DBMI04/. Quaderni di Geofisica, 49, pp.38. 
 16


Strong-motion parameters of the Mw=6.3 Abruzzo (Central Italy) earthquake

https://www.earth-prints.org/bitstream/2122/8368/1/Ameri_et_al_Web_Products_2009.pdf

Strong-motion parameters of the Mw=6.3 Abruzzo (Central Italy) earthquake

Abstract

Similar works

Full text

Available Versions

Earth-prints