Seismic waves and surface waves: past and present

the author presented this lecture after a one-year stay at unam, in mexico. the link between latin american and german earth scientists is invoked by citing the example of alexander von humboldt. some aspects of the evolution of seismology in general and particularly in jena are discussed. special attention is paid to developments in wave theory and the theory of surface waves. this presentation was given on june 16, 2000 in the great hall of the friedrich-schiller university jena on the celebration of "hundred years of earthquake research at jena."