Identification, Association and Analysis of Rayleigh Waves in the Context of CTBT Monitoring
Abstract
The correct identification and association of Rayleigh waves is vital within the context of the CTBT because of the use of the body-wave to surface wave magnitude ratio m(b):M(s) as a discrimination method. Rayleigh waves can be identified by their dispersion characteristics (the variation in group speed with frequency) and their elliptical polarization in the plane of propagation. Classically, Rayleigh waves are associated with a seismic disturbance by calculating the angle from which the wave arrives at a recording station (the 'back-azimuth'). Recently, two approaches to the detection of Rayleigh waves have been proposed (North and Woodgold, 1994; Chael, 1997) which rely on Rayleigh wave dispersion and polarization characteristics respectively. Currently, the identification of Rayleigh waves at the IDC relies on software developed using the methodology of North and Woodgold (1994) and the group speed model of Stevens and McLaughlin (1996). The REB records the arrival time (and residual from the model), an amplitude measurement and consequent calculated M(s). Back-azimuths are also measured and recorded in the REB, although these are not used in associating a Rayleigh wave with a given seismic disturbance.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2000
- Accession Number
- ADA529940
Entities
People
- Neil D. Selby
Organizations
- Ministry of Defense