Near‐surface three‐dimensional multicomponent source and receiver S‐wave survey in the Tannwald Basin, Germany: Acquisition and data processing

Abstract

Shallow 3‐D reflection seismic surveys using S‐waves have rarely been carried out, even though S‐waves can provide higher resolution subsurface images than P‐waves. We conducted a 3‐D near‐surface multicomponent source and receiver survey in Quaternary sediments. We employed a small electrodynamic seismic source with a horizontal shaking unit operated in two orientations. Three‐component geophones in an orthogonal layout covering an area of 117×99 m2 were used for recording. Changes in weather and ground conditions, including freezing and thawing during acquisition, directly influenced the data quality and resulted in discernible relative time shifts in the data. Our seismic processing flow included a four‐component rotation of the data from the Cartesian acquisition geometry into the ‘natural’ coordinate frame to orient sources and receivers in radial or transverse orientation to separate different S‐wave polarizations. The rotation increased the signal strength and helped, for example, to improve the quality of the images of the basin base. The irregular offset distribution in the common midpoint gathers impedes filtering to suppress surface waves in the f–k domain. We, therefore, applied a common‐reflection surface processing flow. After regularization, we could better remove the energy of the surface waves. Both stacked 3‐D S‐wave volumes of vertical and horizontal polarizations provide images of the Quaternary overdeepened Tannwald Basin that was partly known from previous P‐ and S‐wave 2‐D surveys. Compared to a P‐wave profile adjacent to the volume, however, the S‐wave volumes provide higher resolution images of the basin base and internal structure. The basin base is well mapped in three dimensions and shows undulations that were not obvious from the P‐wave data. Comparing the S‐wave volumes of different polarizations, we find only minor differences in the stacks and interpretations.

Drilling Overdeepened Alpine Valleys (ICDP-DOVE): quantifying the age, extent, and environmental impact of Alpine glaciations

“…This has already been done by P-wave reflection seismic data for 5068_1 (Burschil et al, 2018) and 5068_2 (Brandt, 2020), providing a very good resolution to image the valley base and some prominent unconformities. For 5068_2, S-wave data and two small 3D seismic surveys (P-and S-waves) were also carried out (Buness et al, 2020(Buness et al, , 2022Burschil et al, , 2022. Aiming to compare the different sites and, thus, catchment areas, 2-D seismic P-and S-wave surveys at the 5068_4 and 5068_5 site are envisaged.…”