Everywhere I felt transported by the powerful feelings born of my Jena experience: as Goethe's profound insights on nature had raised me to a state where I felt as if endowed with new sensory organs'. 'Whether deep in the Amazon forests or on the high peaks of the Andes I could perceive, from pole to pole, the same pulse of life in rocks, plants and animals that animates the human spirit. In a letter of 1806 addressed to Karoline von Wolzogen he reminisces: The association of earthquake science with Jena becomes clear when one considers Humboldt's interest in the classics. The concept of volcanism was then broader than it is today, as tectonic processes were included. We owe Humboldt an early monographic treatment of some specific earthquakes, and geologist Leopold von Buch (1774≡853) the earliest scientific earthquake theory based on the assumption of a causal connection with volcanism. A celebration of hundred years of seismology in Jena is most timely as it allows me to express our indebtedness to the great naturalist Alexander von Humboldt (17691859, see Ertel, 1953).

While the subject may have seemed rather exotic at the time and still is, at least in some parts of Europe it fitted the universality of Goethe's genius. Eggeling, Rudolf Straubel and Adolf Winkelmann pioneered seismological research in Jena. In a letter to Schiller (1800), Johann Wolfgang von Goethe called the city of Jena a 'mainspring of knowledge.' Farsighted scientists such as Heinrich v. Key words: history of seismology, wave theory, surface waves. This presentation was given on Jin the great hall of the FriedrichSchiller University Jena on the celebration of 'Hundred Years of Earthquake Research at Jena.' Special attention is paid to developments in wave theory and the theory of surface waves. Some aspects of the evolution of seismology in general and particularly in Jena are discussed. The link between Latin American and German Earth scientists is invoked by citing the example of Alexander von Humboldt. The author presented this lecture after a oneyear stay at UNAM, in Mexico. Palabras clave: historia de la sismología, teoría de ondas, ondas superficiales. El trabajo fue presentado en el Gran Auditorio de la Universidad Federico Schiller en Jena, Alemania, como una conferencia invitada en ocasión de la celebración del Centésimo Aniversario de la Investigación Sismológica en Jena. Se analizan algunos aspectos de la evolución de la sismología en general, y en Jena en particular, que tocan el desarrollo de la teoría de ondas y específicamente, de las ondas superficiales. La fértil relación entre las ciencias de la tierra de América Latina con Alemania se remonta a Alejandro von Humboldt. La presente disertación fue presentada por el autor a raíz de una estancia de un año en la Universidad Nacional Autónoma de México. *Corresponding author: September 22, 2011. The distance to the reflector can be found from the reflection arrival time at the source point if the velocity is known.Seismic waves and surface waves: past and presentįriedrichSchillerUniversitat Jena Institut für Geowissenschaften Jena, Germany. The arrival time-versusoffset relation for a plane reflector and constant velocity is hyperbolic. In such cases, a two-dimensional solution is generally used.

However, the dip is often very gentle and the direction of profiling is frequently nearly along either the direction of dip or the direction of strike. In general, this is a problem in three dimensions. The basic problem in reflection seismic surveying is to determine the position of a bed that gives rise to a reflection on a seismic record. Although this assumption is rarely even approximately true, it leads to simple formulas that give answers that are within the required accuracy in many instances. The simplest assumption, which is made in §4.1, is that the velocity is constant between the surface and the reflecting bed. However, even if we had such a detailed knowledge of the velocity, the calculations would be tedious often we assume a simple distribution of velocity that is close enough to give useable results. The accurate interpretation of reflection data requires a knowledge of the velocity at all points along the reflection paths. This chapter uses a geometrical-optics approach to derive the basic relationships between traveltime and the locations of reflecting/refracting interfaces most structural interpretation relies on such an approach.

Seismac waves