HR: 0830h
AN: S51E-0088    [PDF]
TI: Uncertainty Analysis For Seismic Hazard In Northern And Central Italy
AU: Lombardi, A
EM: lombardi@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, via di Vigna Murata, 605, Rome, 00143 Italy
AU: * akinci, a
EM: akinci@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, via di Vigna Murata, 605, Rome, 00143 Italy
AU: Malagnini, L
EM: malagnini@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, via di Vigna Murata, 605, Rome, 00143 Italy
AU: Mueller, C
EM: mueller@usgs.gov
AF: U.S. Geological Survey, DFC MS 966 Box 25046, Denver, CO 80225 United States
AB: We investigate the uncertainty of estimated peak ground acceleration (PGA) for different input variables in three zones of Italy (Eastern Alp, Western Alp, Apennines). The process of earthquake occurrence is assumed Poissonian and the mean hazard maps of 10% probability of exceedence of PGA in 50 years are generated by following the basic methodology of Cornell. The hazard is characterized by using the Frankel's approach: the historical seismicity is spatially-smoothed to different length scales. Three different attenuation relationships are used for hazard calculations in each zone and then weighted through a logic tree. Different uncertainty maps are obtained by the Cramer's approach for every zone: ú the overall uncertainty maps are estimated by simultaneously varying, in a Monte Carlo series of runs, all parameters considered: they provide a confidence interval for PGA values of the mean hazard maps; ú the parameter uncertainty maps are obtained by separately varying each parameter: by them it is possible to determine sensitivity on uncertainty of every input parameter. The parameters considered in every zone are (1) maximum magnitude, (2) attenuation law and (3) b-value. Our results show that ú changes on the maximum magnitude have least effects on hazard calculation than the b-value; ú the attenuation relationship is the parameter which has the most high impact on the hazard assessment. These results provide important information about the most beneficial areas of investigation for reducing uncertainty in seismic hazard calculation in North and Central Italy.
DE: 7223 Seismic hazard assessment and prediction
SC: Seismology [S]
MN: 2003 Fall Meeting