Non Invasive Site Characterization

Institution:
University of Grenoble Alpes
Specialization:
ES - Engineering Seismology
Term:
Fall 2015
Teacher(s):
CECILE CORNOU, MARC WATHELET
Credits:
3
Date (from - to):
01/09/2015 – 29/01/2016

In recent years, the number of research papers dealing with ambient vibration analysis methods has increased considerably. Clearly, the interest in these methods originates from both the economical attractive cost benefit ratio and the straightforward data acquisition. Being non‐destructive, these passive techniques complement geotechnical and/or active geophysical methods. This course will achieve the necessary understanding for the problems related to the use of microtremor for geophysical exploration, why may prove very useful for many applications well beyond earthquake engineering:

  • Physical background of ambient vibrations, linkage between subsurface structure and wave field propagation properties, relevancy for geophysical prospecting and site microzonation;
  • Array processing methods (f‐k based, SPAC, noise correlation techniques, state‐of‐the art of other specific techniques) to measure surface wave dispersion curves;
  • Inversion of shear‐wave velocity profiles: state‐of‐the art of different inversion schemes, objective assessment of final uncertainties on velocity profiles and on main engineering parameters (vs30, response spectra).

This course will contain alternance of lectures and exercises. All exercises will be performed by using a platform‐free software that incorporates the latest developments in each technique (http://www.geopsy.org).

Suggested readings:

  • Aki, K. (1957). Space and time spectra of stationary stochastic waves, with special reference to microtremors, Bull. Earthq. Res. Inst. 35, 415‐456.
  • Bard, P.‐Y. (1999). Microtremor measurements: a tool for site effect estimation?, State‐of‐the‐art paper, 2nd International Symposium on the Efects of Surface Geology on Seismic Motion, Yokohama, Balkema, 3, 1251‐‐1279.
  • Capon, J. (1969). High‐resolution frequency‐wavenumber spectrum analysis, Proc. IEEE 57, 1408‐1418.
  • Tokimatsu, K. (1997). Geotechnical site characterization using surface waves, In Proc. 1st Intl. Conf. Earthquake Geotechnical Engineering, Ishihara (ed), Balkema, 1333‐1368.
  • Wathelet M. (2008). An improved neighborhood algorithm: Parameter conditions and dynamic scaling, Geophysical Research Letters, 35, L09301, doi:10.1029/2008GL033256.
  • Cornou, C., M. Ohrnberger, D. M. Boore, K. Kudo, P.‐Y. Bard (2006). Using ambient noise array techniques for site characterisation: results from an international benchmark, in Proc. 3rd Int. Symp. on the Effects of Surface Geology on Seismic Motion, Grenoble, 29 August ‐ 01 September, 2006.
  • Bard, P.Y., Chaljub, E., Cornou, C., Cotton, F. and Guéguen, P. Editors, LCPC Editions, paper NBT.
  • Picozzi, M, S. Parolai, D. Bindi,A. Strollo, 2009. Characterization of shallow geology by high‐frequency seismic noise tomograpy, GJI, 176, 164‐174.