Topographic versus stratigraphic amplification: mismatch between code provisions and observations during the L’Aquila (Italy, 2009) sequence

• Published in: Bulletin of earthquake engineering Vol. 11; no. 5; pp. 1325 - 1336
• Main Authors: Gallipoli, M. R., Bianca, M., Mucciarelli, M., Parolai, S., Picozzi, M.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-10-2013; Springer Nature B.V
• Subjects: Accelerometers; Amplification; Civil Engineering; Earth and Environmental Science; Earth Sciences; Earthquake engineering; Earthquakes; Environmental Engineering/Biotechnology; Equivalence; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Original Research Paper; Ridges; Seismic phenomena; Seismology; Slopes; Stations; Stratigraphy; Structural Geology; Topography; L’Aquila earthquake; Seismic code; Topographic effects; Site amplification
• ISSN: 1570-761X; 1573-1456
• DOI: 10.1007/s10518-013-9446-3

During the L’Aquila seismic sequence (Italy, 2009) we had the opportunity to install temporary accelerometric stations to study the role of seismic site amplification in damage enhancement. Two of the monitored sites, Castelnuovo and Navelli were also a good test for the recently introduced Italian seismic code (NTC08
2008
) that prescribes an aggravation factor for slopes and ridges. Castelnuovo was an ideal situation to check the rule proposed for the distribution of amplification as a function of the position along a slope, while Navelli provided the possibility to test the almost equivalent factors that NTC08 sets for stratigraphic and topographic amplification (respectively up to 40 and 60 %). In neither case the observation matches code provisions. For Castelnuovo, there is a frequency dependence that shows as the code is over-conservative for short periods but fails to predict amplification in the intermediate range. For Navelli, the code provision is verified for long periods, but in the range around the site resonance frequency the stratigraphic amplification proves to be three times more important than the topographic one.