OCTOBER 28, 2022 at 10:30am CT
Speaker: Andreas Fichtner, Professor of Seismology & Wave Physics, Institute of Geophysics, ETH Zürich
Host: Sean Gulick
Title: Fiber-optic seismology in volcanic, glacial and other challenging environments
Abstract: Fiber-optic deformation sensing provides new opportunities for seismic data acquisition with high spatio-temporal resolution. The relative ease of deploying fiber-optic cables, or the possibility to piggyback on existing telecom infrastructure make this technology particularly attractive for environments where large numbers of conventional seismic instruments may be difficult to install. These include active volcanoes, glaciers or densely populated urban centers.
In the first, more observational part of this talk, we will present a series of case studies where Distributed Acoustic Sensing (DAS) greatly improved the location of glacial icequakes, enabled the observation of previously unknown volcanic tremor and resonance phenomena, and increased the number of detected seismic events by two orders of magnitude – all relative to data from existing seismometer networks.
In the second, more theoretical part, we will report on the development of a novel fiber-optic sensing system that is based on the transmission of microwave-modulated laser pulses. While being more than 10 times cheaper than most DAS systems, the microwave system allows for interrogation distances of hundreds or thousands of kilometers. We show theoretically that different segments of the fiber can have different sensitivities for deformation sensing, largely depending on fiber curvature. Data from a large-scale experiment in Athens support this theory, thereby suggesting that tomographic imaging in remote regions and in the oceans should be possible.
Biography: Andreas Fichtner is Professor of Seismology & Wave Physics at ETH Zurich. He received his PhD in 2010 from LMU Munich for his work on Full Seismic Waveform Modelling and Inversion. After spending three years as postdoctoral researcher, he joined ETH Zurich in 2013.
His research interests include theoretical and computational seismology, inverse theory, the translation of seismic imaging techniques to medical ultrasound, and distributed acoustic sensing in environments where conventional seismometer arrays are difficult to install.
Andreas Fichtner is the editor of one and author of four books on topics ranging from applied mathematics to general geophysics and inverse theory. He received the 2011 Keitii Aki Award from the American Geophysical Union in 2015, the 2015 Early Career Scientist Award from the International Union of Geodesy and Geophysics, as well as serval other recognitions.