Senior Scientist (Oberassistent)
ETH Geophysics, Seismology and Wave Physics
daniel.bowden@eaps.ethz.ch
I am committed to better characterizing seismic hazard, and want to advance our understanding of how waves move and amplify in the shallow crust. I am interested in all things related to seismic array processing, signal processing, and wave propagation physics.
My most resent rearch focuses on the use of new fiber-optic methods (including Distributed Acoustic Sensing) to use pre-existing telecommunications fibers to measure strain-rates. I have helped design and run urban projects in Bern, Athens, and Istanbul, all with a focus on shallow site characterization and microseismic monitoring. Additionally I have helped with the data collection and processing of data from diverse environments such as on volcanos, offshore Santorini, on glaciers, for avalanche monitoring, geothermal sites, and CO2 sequestration.
Regarding site amplifications, we have found that a description of surface wave amplifications leads to frequency and amplitude predictions different from that of a vertically-incident shear wave. This challenges the standard underlying assumption in much of earthquake hazard analysis and engineering, and we are working to develop the formalism by which each type of wave can be properly accounted for.
Much of my research exploits the ambient noise wavefield, and I study the extent to which crustal properties such as site-response, attenuation, and scattering can be resolved from signal amplitudes. Direct observations of the shallow crustal structure's effect on the ambient noise wavefield can be used to validate more traditional wave propagation methods for seismic hazard estimates.
Previous studies have included noise tomography with an OBS array offshore southern California, the deployment and analysis of a 3D broadband array at the Homestake Mine in South Dakaota, and the analysis of wavefronts propagating across big-N arrays like the UsArray and Long Beach Nodal array.
More on research
We're trying a new thing! Check out our group's YouTube Channel for video summaries of our research projects and papers:
- Our latest fiber sensing project in Istanbul, Turkey: [Video]
- Connecting different kinds of fiber-optic seismic sensing: [Video]
- On Beamforming and Noise Source Inversion: [Video]
A big thanks to Jonas Igel for filming and editing help.