Skip to Main Content
GEOREF RECORD

Assessing regional and site-dependent variability of ground motions for ShakeMap implementation in Italy

P. L. Bragato
Assessing regional and site-dependent variability of ground motions for ShakeMap implementation in Italy
Bulletin of the Seismological Society of America (October 2009) 99 (5): 2950-2960

Abstract

This study investigates the theoretical improvement of the ground-motion models used for ShakeMap implementation in Italy, obtainable by accounting for regional differences of wave propagation and for site effects. The analysis considers 922 recordings of 116 earthquakes with local magnitude M (sub L) in the range 2.7-4.5, collected from 137 stations at epicentral distances up to 100 km. Alternative partitions of the available stations divided into separated zones are considered. For each zone in a partition, an empirical ground-motion model is estimated, which includes station correction terms. A genetic algorithm is used in order to minimize the standard deviation of the residuals log (sub 10) (observed)-log (sub 10) (predicted) over the set of the possible partitions. For the logarithm of the peak ground acceleration, it is estimated that site effects contribute to about 30% of the overall standard deviation, while regional differences contribute with no more than 4%. Furthermore, the estimated station correction terms are weakly correlated with the amplification factors based on shear-wave velocity in the upper 30 m (V (sub S30) ) used in ShakeMap to model site effects. Similar results apply to peak ground velocity and spectral acceleration response at 0.3, 1, and 3 sec. These results suggest that parametrizations of site effects alternative to those based on V (sub S30) should be considered, while the contribution of any regionalization of the ground-motion models is marginal.


ISSN: 0037-1106
EISSN: 1943-3573
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 99
Serial Issue: 5
Title: Assessing regional and site-dependent variability of ground motions for ShakeMap implementation in Italy
Author(s): Bragato, P. L.
Affiliation: Istituto Nazionale di Oceanografia e di Geofisica Sperimentale-OGS, Dipartimento Centro di Ricerche Sismologiche, Udine, Italy
Pages: 2950-2960
Published: 200910
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 30
Accession Number: 2009-095010
Categories: SeismologyEngineering geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sketch maps
N36°30'00" - N47°30'00", E06°30'00" - E19°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200951
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal