 |
| Titel |
Exploring the potentials and limitations of the time-reversal imaging of finite seismic sources |
| VerfasserIn |
S. Kremers, A. Fichtner, G. B. Brietzke, H. Igel, C. Larmat, L. Huang, M. Käser |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1869-9510
|
| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 2, no. 1 ; Nr. 2, no. 1 (2011-06-21), S.95-105 |
| Datensatznummer |
250000455
|
| Publikation (Nr.) |
 copernicus.org/se-2-95-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
The characterisation of seismic sources with time-reversed wave
fields is developing into a standard technique that has already been
successful in numerous applications.
While the time-reversal
imaging of effective point sources is now well-understood, little
work has been done to extend this technique to the study of finite
rupture processes. This is despite the pronounced non-uniqueness in
classic finite source inversions.
The need to better constrain the details of finite rupture
processes motivates the series of synthetic and real-data time
reversal experiments described in this paper. We address questions
concerning the quality of focussing in the source area, the
localisation of the fault plane, the estimation of the slip
distribution and the source complexity up to which time-reversal
imaging can be applied successfully. The frequency band for the synthetic
experiments is chosen such that it is comparable to the band usually employed for
finite source inversion.
Contrary to our expectations, we find that time-reversal
imaging is useful only for effective point sources, where it yields
good estimates of both the source location and the origin time. In
the case of finite sources, however, the time-reversed field does
not provide meaningful characterisations of the fault location and
the rupture process. This result cannot be improved sufficiently
with the help of different imaging fields, realistic modifications
of the receiver geometry or weights applied to the time-reversed
sources.
The reasons for this failure are manifold. They include the choice of the frequency band,
the incomplete recording of wave field information at the surface,
the excitation of large-amplitude surface waves that deteriorate the
depth resolution, the absence of a sink that should absorb energy
radiated during the later stages of the rupture process, the
invisibility of small slip and the neglect of prior information
concerning the fault geometry and the inherent smoothness of seismologically inferred Earth models that prevents
the beneficial occurrence of strong multiple-scattering.
The condensed conclusion of our study is that the
limitations of time-reversal imaging – at least in the frequency band
considered here – start where the seismic source stops being effectively
point-localised. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|