Bulletin of the Seismological Society of America; December 2000; v. 90; no. 6;
p. 1549-1553; DOI: 10.1785/0120000004
© 2000 Seismological Society of America
Coexistence of Gravity Waves and Elastic Waves in Unconsolidated Sediments
R. Esquivel-Sirvent
Instituto de Física
UNAM
Apartado Postal 20-364
México, D.F. 01000, Mexico
Based on a linear viscoelastic model, we study the coexistence and
transition of gravity waves and surface elastic waves in a half-space of
unconsolidated sediment. The dispersion relation and surface response are
calculated as a function of the period and rigidity of the system. The
dispersion relation shows two branches. One branch corresponds to a Rayleigh
wave for short-wave periods, and it becomes a leaky surface wave as the period
increases. The second branch shows a linear dependence of the phase velocity
with period as expected for gravity waves. As the period increases, this
branch evolves into a leaky surface wave joining the first branch. The surface
response function, which is related to the vertical displacement, is also
calculated. Two distinct peaks are present in the surface response function.
One corresponds to a classical Rayleigh wave, while the second is a
gravity-driven mode whose amplitude is strongly dependent on the wave period
and soil rigidity.
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