MULTIPLE COHERENCE OF LONG PERIOD NOISE AT LASA
Abstract
Multiple coherence gives a quantitative measure versus frequency of how well a linear combination of n input channels can match the (n + 1) st channel in a seismic array. If the inputs can match the output exactly, then the multiple coherence is unity and only n channels are necessary to describe the noise field. This report shows multiple coherence versus frequency with 2 to 9 input channels for long period, vertical component noise fields at LASA. Over the 7 to 20 seconds period range the multiple coherence on the samples tested were greater than .65 showing that 65% or more of the noise at a center channel is predictable by other seismometer outputs in the array. This level of multiple coherence requires 8 to 9 input channels. Multiple coherence with fewer inputs + ordinary coherence between pairs of channels are must lower. From the samples tested which all produce multiple coherences quite similar to each other, it is concluded that at least 9 input channels are necessary to adequately describe the long period noise at LASA.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 23, 1967
- Accession Number
- AD0816029
Entities
People
- E. F. Chiburis
- William C. Dean
Organizations
- Teledyne Technologies