 |
| Titel |
Seismic imaging of sandbox experiments – laboratory hardware setup and first reflection seismic sections |
| VerfasserIn |
C. M. Krawczyk, M.-L. Buddensiek, O. Oncken  , N. Kukowski |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1869-9510
|
| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 4, no. 1 ; Nr. 4, no. 1 (2013-02-15), S.93-104 |
| Datensatznummer |
250017350
|
| Publikation (Nr.) |
 copernicus.org/se-4-93-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| With the study and technical development introduced here, we combine
analogue sandbox simulation techniques with seismic physical modelling of
sandbox models. For that purpose, we designed and developed a new
mini-seismic facility for laboratory use, comprising a seismic tank, a
PC-driven control unit, a positioning system, and piezoelectric transducers
used here for the first time in an array mode. To assess the possibilities and
limits of seismic imaging of small-scale structures in sandbox models,
different geometry setups were tested in the first 2-D experiments that also
tested the proper functioning of the device and studied the seismo-elastic
properties of the granular media used. Simple two-layer models of different
materials and layer thicknesses as well as a more complex model comprising
channels and shear zones were tested using different acquisition geometries
and signal properties. We suggest using well sorted and well rounded grains
with little surface roughness (glass beads). Source receiver-offsets less
than 14 cm for imaging structures as small as 2.0–1.5 mm size have proven
feasible. This is the best compromise between wide beam and high energy
output, and is applicable with a consistent waveform. Resolution of the
interfaces of layers of granular materials depends on the interface
preparation rather than on the material itself. Flat grading of interfaces
and powder coverage yields the clearest interface reflections. Finally,
sandbox seismic sections provide images of high quality showing constant
thickness layers as well as predefined channel structures and indications of
the fault traces from shear zones. Since these were artificially introduced
in our test models, they can be regarded as zones of disturbance rather than
tectonic shear zones characterized by decompaction. The multiple-offset
surveying introduced here, improves the quality with respect to S / N ratio and
source signature even more; the maximum depth penetration in glass-bead
layers thereby amounts to 5 cm. Thus, the presented mini-seismic device is
already able to resolve structures within simple models of saturated porous
media, so that multiple-offset seismic imaging of shallow sandbox models,
that are structurally evolving, is generally feasible. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|