The nature of particle motion in regional seismograms and its utilization for phase identification
The particle motion of regional arrivals is frequently treated in automatic phase-recognition schemes as that appropriate to simple P or S waves incident on an elastic, laterally homogeneous half-space. This model implies that the motion in ‘ P -type’ phases can be described in terms of a single, ge...
| Published in: | Geophysical Journal International |
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| Main Authors: | , , |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
1993
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| Subjects: | |
| Online Access: | http://gji.oxfordjournals.org/cgi/content/short/115/3/1012 https://doi.org/10.1111/j.1365-246X.1993.tb01506.x |
| Summary: | The particle motion of regional arrivals is frequently treated in automatic phase-recognition schemes as that appropriate to simple P or S waves incident on an elastic, laterally homogeneous half-space. This model implies that the motion in ‘ P -type’ phases can be described in terms of a single, generalized signal process and ‘ S -type’ phases in terms of two independent processes ( SV and SH ) and thus, all regional arrivals could be fully characterized by three components of motion. In this paper, we present anlyses of the particle-motion patterns of various regional arrivals recorded at the ARCESS array from closely spaced events in the Kola Peninsula. We have found that only Pn -particle motion, described in terms of two independent signal processes, can be reliably characterized by three-component recordings. On the other hand, the various regional arrivals following Pn , such as Pg and Sn and Lg , can only be poorly characterized on the basis of three-component recordings alone. The reason is that these arrivals must be described in terms of more than two independent generalized signal processes, at least three for Pg and Sn , and possibly up to five for Lg . Recognition of these phases will thus require the use of more sensors than signal processes in the observing sensor configuration, such as three-component sensors combined with a small tripartite array. We have investigated the feasibility of adaptive, automatic recognition of regional arrivials by a wavefield extrapolation scheme utilizing such a mini-array. The process, which appear to be promising, adaptively learns the particle-motion patterns of individual arrivals, including complex site-response functions, from examples of closely located regional events. |
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