Nodal patterns in the seismic response of sedimentary valleys
Instituto de Física, Universidad Nacional Autónoma de México, Apdo. Postal 20-364, 01000 Mexico, Mexico
Corresponding author: email@example.com
Sedimentary basins, where many large cities in the world are built, have very soft terrains. When an intense seism of long duration hits the sedimentary basin, a nodal pattern, in which regions of high seismic wave amplitudes alternate with regions where these amplitudes are very small and even null, is formed. This nodal pattern, which leads to the so called “pockets of damage”, is always observed, for example, in Mexico City. In this paper the PR mode, in which P-waves in the soft terrain are coupled to the Rayleigh wave produced in the interface with the harder subsoil underneath it, is discussed. It is proposed that this coupled mode is the culprit of the enormous damage observed in sedimentary basins due to their peculiar seismic response.
© EDP Sciences, Springer-Verlag, 2007