Analysis of Strain Seismograph Data
Abstract
Noise power on the short period pendulum and strain instruments has been compared at WMO and HNME. In the response band of the short period instruments, there are approximately four decades of relative power at HNME, and two decades at WMO. In one case analyzed the noise power at HNME is about 2 1/2 times the noise power at WMO at 1 Hz. Coherence was estimated as a measure of the existence of a linear transfer function between the vertical strain and the vertical pendulum. At HNME there exists a well-defined linear transfer function in the band 0.1 to 0.6 Hz. The low coherence at higher frequencies at HNME and throughout the 0.1 to 3.0 Hz band at WMO rule out the possibility of a linear transfer function between the vertical strain and vertical pendulum. Multiple coherence, and rotation of the horizontal short period seismograms were used to infer the existence of unidirectional noise components. At HNME about 80 percent of the noise power is unidirectional in the 0.3 to 0.4 Hz band. Preliminary work on rotation of the horizontal strain instruments at WMO is presented. The technique uses a third horizontal instrument to establish the shear component of strain. Examples of detailed analysis to establish wavetype using the vertical strain, together with the vertical pendulum and horizontal pendulum instruments are included.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 06, 1970
- Accession Number
- AD0866743
Entities
People
- J. R. Woolson
Organizations
- Teledyne Technologies