Seismic hazard is a key instrument for any assessment and mitigation of the seismic risk. It represents a tool for estimating the seismic actions expected at a site on a probabilistic basis. The maps shown hereafter, refer to seismic parameters suitable for engineering purposes, such as spectral ordinates, peak values, and site intensities. All parameters have been computed for a 10% exceedance probability within 50 years, representing the default value assumed in many international seismic codes for the engineering design of civil structures.
Values have been computed on a grid spacing 5x5 Km all over the country. For a more detailed description of the methodologies and data used, please refer to the documentation cited in the references and available for download.
Seismic hazard maps shown hereafter refer to the following parameters:
Peak ground acceleration (PGA)
Spectral Acceleration at 5Hz (0.2 seconds)
Spectral Acceleration at 1Hz (1.0 seconds)
The web-content will be regularly improved and enriched, covering also in the future the topic of the assessment of Seismic Risk in Italy.
NEWS: 22-07-2004
Mesh: 0.05° longitude-latitude equally spaced mesh for computing accelerations at different return periods. Whole Italian country coverage.
Mesh_2_50.txt: 2% exceedance probability in 50 years (2475 yrs. return period)
Mesh_5_50.txt: 5% exceedance probability in 50 years (975 yrs. return period)
Mesh_10_50.txt: 10% exceedance probability in 50 years (475 yrs. return period)
Mesh_50_50.txt: 50% exceedance probability in 50 years (72 yrs. return period)
PGA: peak round accelerations on stiff soils (g’s values)
SA_0.2s: 0,2 seconds spectral accelerations on stiff soils (g’s values)
SA_1.0s: 1,0 second spectral accelerations on stiff soils (g’s values)
Format: 2F10.2, 3F10.5
Uniform hazard spectra with a 10% chance of being exceeded in 50 years (475 yrs. return period). Values have been directly computed to the coordinates of the downtown centres of the Italian villages.
PGA & PGV: peak ground acceleration & velocity (values in g & cm/sec, respectively)
T4.00…T.040: spectral accelerations (in g) from 4,0 to 0,04 second periods.
Romeo, R. & Pugliese, A. (1998). Seismicity, Seismotectonic and Seismic Hazard of Italy. Engineering Geology, 55(4), 241-266.
Romeo, R., Paciello, A. & Rinaldis, D. (1999). Seismic hazard maps of Italy including site effects. Soil Dynamics and Earthquake Engineering, 20(1-4), 85-92.
DECREE 3274 OF THE ITALIAN GOVERNMENT (in Italian). Elements and criteria for the seismic classification of the country.
Links to other Italian sites
concerning the seismic hazard:
http://emidius.mi.ingv.it/GNDT/PS.html#PERICOLOSITA
http://ssn.protezionecivile.it/PROG/2000/carte_pericolosita/index.html
Contacts: geoappl@uniurb.it (specifying 'hazard' in the subject)