Integration of geophysical data in microzonation studies
Abstract
For the realisation of a seismic microzonation study, the geotechnical model is mainly based on geotechnical and geological data and much less commonly on seismological data. The geophysical methods as H over V spectral ratios using a single station and noise signal (H/V method) or the spectral analyses of surface wave (SASW) are poorly used at present. During two microzonation studies in volcanic areas (Mayotte and Guadeloupe Islands), BRGM used these two methods to supply the lack in geotechnical data and to better constrained the soils columns parameters that are used to calculate the ground motion. Theoretically, the two methods are complementary because H/V gives the resonance frequency of the soil, resonance that is correlated to the thickness of the soil and the shear wave velocity. These two parameters can be deduced from the SASW method. But, practically, the results obtained from the two methods are not so easy to interpret. The use of the two methods has given us many useful information but raised also a lot of question as the results of the two methods are not always in coherency or because the depth of investigation of SASW is not sufficient to interpret the H/V results. Using some examples of the results, we will show the interest in using these methods and also the difficulties we had in the interpretation.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....5994L