Site Condition Mapping using Topographic Slopes

We investigate the possibility of adaptation a new method for large scale assessment of seismic site conditions and amplification, by using maps derived from topographic data, making the technique quick and cost effective. The maps uses topography slopes as a proxy for site conditions, based on its close connection to the results of shear wave velocity measurements proved by previously accomplished correlation calculations. The technique was investigated on a test site in Hungary by using SRTM 3 sec maps and VS,30 (average shear wave velocity down to 30 m) results of surface wave measurements carried out previously. Our results show that the measured and calculated VS,30 values are close to one another, but in case of the test and similar areas (characterized by consolidated alluvial deposits) the velocity values scatter around the important boundary level (360 m/s) of “B” and “C” categories. Consequently some refinement of correlation and involving geologic data can be necessary and useful for a more accurate classification.