Iunio Iervolino (University of Naples) - 27/04/10, 5.30pm at UCL
An EPICentre seminar will be given by Iunio Iervolino (University of Naples) at UCL on
Tuesday 27th April, 5.30pm.
Venue: Chadwick Building, room 218 (2nd floor)
see map: http://www.ucl.ac.uk/maps/ucl-maps/map2_low_res
Title: Near-Source Pulse-Like Seismic Demand
Abstract:
Directivity in earthquakes is such that a site located close to the source of a seismic event may be in a geometrical configuration with respect to the propagating rupture favoring the constructive interference of the approaching waves; i.e., a synchronization of phases causing a buildup of energy. This phenomenon requires the rupture propagating toward the site and the alignment of the site with the slip of the fault. Rupture directivity effects in ground motion are known since many years to both seismologists and earthquake engineers; i.e., the velocity fault-normal signals may show a large pulse occurring at the beginning of the record and containing the most of energy. The results are waveforms different from ordinary ground motions recorded in the far field or in geometrical conditions not favorable with respect to directivity. Current attenuation laws are not able to capture such effect well, if at all, and current probabilistic seismic hazard analysis is not able to predict the resulting peculiar spectral shape. Moreover, it is believed that structures with dynamic behavior in a range of periods related to the pulse period may be subjected to underestimated seismic demand. In the talk the near-source issue in earthquake engineering is discussed with respect to both hazard analysis and seismic action on structures. Analyses are based on a large dataset of identified pulse-like records. Finally, the attempt to identify near-source effects in the data recorded during the mainshock of the recent Abruzzo (central Italy) sequence is presented.