Topography effects in the 1999 Athens earthquake : engineering issues in seismology

It is well known that irregular topography can substantially affect the amplitude and frequency characteristics of seismic motion. Macroseismic observations of destructive earthquakes often show higher damage intensity at the tops of hills, ridges and canyons than at lower elevations and on flat areas. Systematic seismic motion amplification over convex topographies has been confirmed by instrumental studies and also predicted by theoretical and numerical simulations of wave diffraction. Nonetheless, for the most part, the former have been limited to weak motion data and the later have treated topographic asperities as simple geometric irregularities on the surface of homogeneous, linearly elastic halfspaces. Despite the qualitative agreement between theory and observations on topography effects, there is still much uncertainty concerning the actual severity of amplification near topographic irregularities, inasmuch as predictive methods are still lacking on the quantitative aspects of seismic amplification near such features. Focusing of seismic rays by convex topographies does play a significant role as shown theoretically, yet it is not the only physical phenomenon involved. On the other hand, weak motion data may not be applicable to describe topography effects for strong shaking, and indeed there exist very few- if any- well documented case studies demonstrating the severity of topographic effects for strong ground motion. In this dissertation, we find that topography and local soil conditions need to be accounted for simultaneously for the prediction of site amplification factors, especially when earthquake motions are strong enough to elicit clear nonlinear soil behavior.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Assimaki, Dominic, 1975-

Advisor dc:contributor.advisor

• Eduardo Kausel.

• Civil and Environmental Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/30048

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/30048