Berkheim

This data set is provided on request for reasearch purposes only. Please contact Thomas Forbriger.

 

Location and site properties

Approximate location of the site: 48.71491°N, 9.32411°E

The subsurface structure at this site is predominantly 1D. The data set was recorded on a hard pitch with black top pavement. The soil below the hard surface is made ground, consisting mainly of loam. The seismic interpretation suggests that in about 5.5 m depth a hard layer is met. According to geological back-ground information this should be jurassic sandstone (Lias α). Forbriger (2001) gives a detailed description of the site.

This site is an excellent example for a pronounced low-velocity-zone. The high-velocity layer at the surface results in anomalous phase-slowness dispersion.

 

Recording parameters

Each shot was recorded with 36 geophones simultaneously. A hammer blow was used as seismic source. Data was recorded by two recording systems:

12-channel BISON 5012

• input resistance: 1.014kOhm
• high-pass: 8Hz, 2nd order, Butterworth
• low-pass: 500Hz, 6th order, Butterworth
• geophones: 10Hz vertical, h=0.682, G=28.8 Vs/m

 

24-channel BISON 9024

• input resistance: 10.14kOhm
• high-pass: 4Hz, 2nd order, Butterworth
• low-pass: 500Hz, 6th order, Butterworth
• geophones: 10Hz vertical, h=0.307, G=28.8 Vs/m

 

Inversion

A joint inversion of the wavefield expansion coefficients (including both body and surface wave signals) and the P-wave arrival times was applied to this data set (Forbriger 2003a and b). Further the full waveform of the field data was modeled from the final model and the force-time function of the source was derived (Forbriger 2004). 

Raw seismogram gather

A hammer blow was used for the recording of this exemplary shot gather.

Velocity model which results from the joint inversion

 

 

References

• Forbriger, T., 2001. Inversion flachseismischer Wellenfelder. Dissertation. Institut für Geophysik, Universität Stuttgart. urn:nbn:de:bsz:93-opus-8610
• Forbriger, T., 2003a. Inversion of shallow-seismic wavefields: I. Wavefield transformation. Geophys. J. Int., 153, 719-734. doi:10.1046/j.1365-246X.2003.01929.x
• Forbriger, T., 2003b. Inversion of shallow-seismic wavefields: II. Inferring subsurface properties from wavefield transforms. Geophys. J. Int., 153, 735-752. doi:10.1046/j.1365-246X.2003.01985.x
• Forbriger, T., 2004. Dynamics of the Hammer Blow. In: Symposium in Memoriam of Prof. Gerhard Müller, J. Schweitzer (ed.). Deutsche Geophysikalische Gesellschaft, ISSN-Nr. 0934-6554, I/2004, 93-97. urn:nbn:de:swb:90-78180