Extension of Ms(VMAX) to Global Paths
Abstract
Recent work with a prototype application for variable-period Rayleigh-wave magnitudes (Russell, 2006) has reported use of the Ms(VMAX) technique for periods between 8 and 25 seconds (Bonner et al., 2006a, 2006b, 2007). More recently, the technique has been extended to 40 seconds (Bonner, 2007). In all previous studies, the data were limited to continental paths and thoroughly reviewed. This study has attempted to evaluate an operational scenario whereby all surface-wave paths are considered. Two groups of data have been utilized, twenty-seven (27) shallow events from the Asian continent and a larger (143 events) global event group with a broader depth range. All events have been reviewed by an analyst for validity. To obtain a better understanding of period and path effects, the data have been subdivided into three period ranges (8 - 17 seconds, 17 - 25 seconds, and 25 - 40 seconds) and separated by predicted group slowness into oceanic paths (slow < 32.25 sec/deg), continental paths (slow > 38.0 sec/deg), and mixed oceanic-continental paths (32.25 sec/deg less-than-or-equal-to slow less-than-or-equal-to 38.0 sec/deg). Past studies have demonstrated the Ms(VMAX) technique works well for continental paths between 8 and 25 seconds (Bonner et al., 2006b, 2007). This study shows stable results for all paths (oceanic, mixed, and continental) between 8 and 25 seconds. Since the data have been shown to be path independent, the Ms(VMAX) technique may provide an automated replacement for Ms, allowing the inclusion of regional stations with Airy phases and reducing the analyst burden.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2008
- Accession Number
- ADA516184
Entities
People
- Anne S. Henson
- Brian M. Pope
- Gordon D. Kraft
- Jill M. Franks
- Kevin D. Hutchenson
- Michael F. Jezard
- Michael S. Antolik
- Richard A. Reed
- Siroos Motlagh
- Steven J. Leclaire