SEG Honorary Lecturer Near Surface 2013

Valentina Socco

Valentina Socco

(Politecnico di Torino, Italy)

"Surface wave analysis for near-surface characterization: Introduction, theme and variations"

Erfahrungsbericht

(von Aglaja)

Im Rahmen der SEG Near Surface Lecture Tour 2013 hatten wir, die SGS, die Ehre, Valentina Socco bei uns am 03.09.2013 an der Freien Universität in Berlin begrüßen zu dürfen.
Das Aufeinandertreffen begann bereits einen Tag vorher bei einem gemeinsamen Dinner im wunderschönen Nikolaiviertel in Berlin Mitte. Umgeben vom ältesten Wohngebiet Berlins und somit auch der Geschichte vergangener Tage, speisten wir im rustikal-antiken Restaurant „Zum Paddenwirt“ und führten angeregte Gespräche. Valentina Socco war besonders an dem deutschen Uni-System und den Zukunftsplänen jedes einzelnen Studenten interessiert und gab uns dazu auch ein paar Tipps. Auch diskutierten wir angeregt über die außerordentlichen Kaffee-Gewohnheiten der Italiener.
Am 03.09.2013 begrüßten wir Frau Socco auf unserem Geo-Campus in Lankwitz und führten sie durch das Geophysikgebäude, sowie durch die Gerätehalle und das Gesteinsphysiklabor, in welchem sie durch ein Mitglied eine kleine Führung bekam. Zum Lunch ging es in unsere Cafeteria, in der Frau Socco mit weiteren Mitarbeitern und Studenten unserer Fakultät ins Gespräch kam.
Anschließend folgte der Vortrag im Haus C, welcher erfreulicherweise recht gut besucht war. Eine bunte Mischung aus Geophysikstudenten der FU, TU und Uni Potsdam, aber auch Studenten aus weiteren Fachrichtungen, wissenschaftlichen Mitarbeitern der FU, sowie des GFZ waren anwesend. Die informative und interessante Präsentation dauerte knapp 90 Minuten und endete mit einer Diskussionsrunde, in der alle aufgekommenen Fragen beantwortet werden konnten. Zum Abschluss wurden die Vorsitzenden des SEG Student Chapters von Valentina Socco zum Kaffee eingeladen, bei dem wir ihr ein Feedback zu ihrem Vortrag gaben. Am Hauptbahnhof verabschiedeten wir uns von ihr und wünschten ihr eine weitere erfolgreiche Lecture Tour.

Abstract

While seismologists have been using surface waves to image the Earth's crust since the ‘60s and geotechnical engineers developed surface-wave analysis methods to characterize the soil in the ‘80s, we have had to wait until the last decade to see surface-wave analysis becoming a standard method in seismic exploration. Nowadays, surface waves, which are traditionally considered noise in seismic gathers, have shown the potential of estimating the shear properties of the shallow subsurface. They are, hence, routinely used in many near-surface applications that range from seismic hazard studies to the building of weathering-layer velocity models for seismic reflection corrections.

Different kinds of surface waves can be gathered, according to the environment and the subsurface conditions: Rayleigh waves, from land surveys, Scholte waves, in marine environments, Love waves, when horizontally polarized sources and receivers are used, Lamb waves or P-guided waves, when very high-impedance contrasts are present. Regardless of the kind of waves, the most established analysis method is based on the inversion of the geometrical dispersion of surface waves. This approach, which exploits the relationship between the vertical distribution of the seismic properties in the subsurface and the phase velocity of different surface wave harmonics, only considers the kinematics of the propagation and is based on several simplified assumptions. I will examine the potentials and limitations of this approach and different technical solutions for acquisition, processing, and inversion in the context of different applications.

The most important assumptions that are usually made in surface-wave analysis are that the site is 1D and that the experimentally retrieved dispersion curve coincides with the surface-wave fundamental mode. Both assumptions are often violated and specific measures have to be taken to handle multimodal propagation in laterally varying environments. Several technical solutions have been proposed and I will discuss them to define the best practice for surface-wave analysis in complex geologic conditions. Recently, tomographic techniques, which are usually applied in seismology, have been adapted to active seismic data. Their potentials and requirements will be presented.

Content: Society of Exploration Geophysicists

Biography

Laura Valentina Socco is presently associate professor in Applied Geophysics at the Politecnico di Torino, where she obtained her PhD in environmental geo-engineering (1997) and her MSc in civil engineering (1992). She has been in charge of the Applied Geophysics Lab at the Politecnico since 2007. Her research work covers several near-surface geophysical methods and applications, and, over the last decade, has focused on surface-wave methods and geophysical data integration for near-surface characterization, with particular regard to the development of new processing and inversion approaches. She is author of about 100 peer-reviewed scientific publications in journals and for conferences and has been given an honorable mention for Best Paper in Geophysics in 2012. She is member of the EAGE Research Committee, and is vice-chairwoman of the EAGE Near Surface Division Committee. She is Associate Editor of Geophysics (since 2003) and Near Surface Geophysics (since 2006). She has been the principal investigator of many research projects financed by national and international institutions as well as by private companies. She teaches geophysical prospecting in the Petroleum Engineering MSc Program. She has been advisor of more than 40 MSc and of 5 PhD theses. She has been convener of several workshops at EAGE conferences and an invited speaker at international conferences and research institutions.

Content: Society of Exploration Geophysicists

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Fotos: Florian / SGS