DEEP-WELL RESEARCH
Abstract
Vertical arrays of four vertical seismometers were operated in the deep hole at sites near Apache, Oklahoma, and Franklin, West Virginia. At each site a fifth deep-hole seismometer was operated in a shallow hole adjacent to the deep hole as a surface reference. The deep hole near Apache was filled with water to within 75 m of the surface. Measurements at this site were interrupted when the hole was filled and have not resumed. Design improvements to the deep- hole, short-period triaxial seismometer were completed. A vertical array of up to four triaxial seismometers in one hole was designed and is under construction. The normal response of the deep-hole vertical seismograph was modified to peak at higher frequencies by use of a 10-cps galvanometer and auxiliary-filter amplifiers. Also, work was done to extend the response of both the vertical and the triaxial seismographs to provide long-period responses peaked near 20 seconds. The test site near Grapevine, Texas was maintained in operation to perform tests and experiments on the triaxial seismometer. Additionally, seismographs with special responses were tested there. Results of data analyses indicate that changes in the shear velocities assumed in the Rayleigh wave computer program do not appreciably change the amplitude-depth relationships. Spectral analyses of teleseismic P waves indicate that enough S- wave energy is present to degrade the filters that eliminate the surface reflections. Several examples of the results of attempts to eliminate the surface reflections are shown; results are good for the first few cycles.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 15, 1965
- Accession Number
- AD0625515
Entities
Organizations
- Geotech Instruments (United States)