Abstract of the proposal "Seismic Interferometry; Validation with the TRex Shaker and Application to SAFOD" (Geophysics Proposal ID: 0609595)
Seismic interferometry is an emerging line of research in physics, acoustics, and geophysics where on retrieves the waves that propagate between two receivers from the recording of incoherent signals. This creates recordings of the wave field as if there was a source placed at the location of one of the receivers. This is a powerful technique, because it allows for an illumination of the subsurface that often can not be achieved practically with real, controlled sources.
We further develop the theory and practical implementation of seismic interferometry and validate this using data collected in the Garner Valley project with Trex-shakers. There are large vibrators that shake the Earth's surface in three orthogonal directions. We compare the wave response this obtained with the waves extracted from seismic interferometry using natural sources.
Another application of seismic interferometry that we investigate is focused on the San Andreas Fault Observatory at Depth (SAFOD), one of the experiments carried out as part of Earthscope. Using seismic interferometry, we use drill-bit noise generated as a the main hole was drilled, to provide a "broadside-illumination" of the San Andreas fault. This waves reflected from the San Andreas fault can then be used to analyze the detailed structure of this fault zone.
The support requested in this project is primarily used to educate a graduate student. A major application of seismic interferometry is to monitor natural hazards (faults, volcanoes, landslides) in situations where natural or man-made seismic sources are lacking. Moreover, seismic interferometry can be used to passively monitor buildings, and the aging infrastructure (such as bridges) in the US.
