Crustal Structure in the Wisconsin Area
Abstract
Seismic results from six large blasts in the Wisconsin area are reported. The observations were made with a group of 12 three-component instruments, of period 1 second, located on a selected be-rock sites. Time signals at 1 second intervals were transmitted by radio. On the scale of the present experiments which involved an area about 600 km long by 150 km wide, the major structure revealed was a relatively homogeneous layer about 40 km thick. The time-distance segment corresponding to this layer is always nearly linear; and, at the four areas investigated implies compressional wave velocities of 6.16, 6.26, 6.22 and 6.16 km/sec respectively. Although the assumption of a homogeneous layer of uniform wave velocity leads to satisfactorily small residuals (see Table 1 - the mean absolute value for 8 residuals for the Davenport blast is, for example, .09 seconds), an improved fit with the observed time-distance data results throughout the area if the wave velocity in the major layer is assumed to increase linearly with depth, in accordance with teh relations: v = 6.034(1 + .0038z) (Northern Area), v = 5.94(1 + .0045z) (Southern Area) where z = depth below top layer in km.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 31, 1951
- Accession Number
- AD0624629
Entities
People
- L. B. Slichter
Organizations
- University of California, Los Angeles