S23E-07:
The Ground Truth of Crustal Anisotropy from Receiver Functions
Abstract:
As one of the rare observational tools for studying deformation and stress within the Earth, seismic anisotropy has been one of the focuses of geophysical studies over the last decade.
To test this technique, we need a crustal block where the underground structure is reasonably well-known, e.g., where there is extensive knowledge from local seismic experiments and drilling. Therefore a field test around the KTB (Kontinental Tiefbohrung) site in the Oberpfalz in Southeastern Germany, has been carried out to test the technique, and to compare with previous results from deep drilling, and high-frequency seismic experiments around the drill site.
The investigated region has been studied extensively by local geophysical experiments. The deep borehole was placed into gneiss rocks of the Zone Erbendorf-Vohenstrauss. Drilling activity lasted from 1987 to 1994, and descended down to a depth of 9101 meters, sampling an alternating sequence of paragneiss and amphibolite, with metamorphism of upper amphibolite facies conditions, and ductile deformation produced a strong foliation of the rocks.
The application of the RFs reveals strong seismic anisotropy in the upper crust related to the so-called Erbendorf body.